Safe sodium carbonate.

Discussion in 'Black and White' started by patrick_gainer, Jun 23, 2004.

  1. I have received from a 17 pound pail of
    anhydrous sodium carbonate. The MSDS sheet accompanyinf it saya it is
    100% sodium carbonate. The price was $15.98 + shipping. Is there a
    reason I should not use this in any of my B&W photographic solutioons
    that call for sodium carbonate?
  2. I don't see why not.
    Only remember the conversion factors between anhydrous and hydrated carbonate
  3. Well, right off the bat we know they're lying. Nothing is 100%- there have to be some traces of something in there. Now that we've established they can't be trusted, it's just a question of how far they'll go to mislead you. Heck, the stuff might be more contaminated than my pool chemicals. BTW, I don't place any stock in MSDS sheets for content anyway. They fulfill a regulatory need, but they have nothing in common with an assay of what's really there. Ok, seriously, I wouldn't hesitate to use the stuff. Now, where's the cheapest sulfite?
  4. Conrad,

    I can tell by your reply that you know my question was rhetorical. I was planning to use it anyway.

    100% in engineering terms means a purity greater than 99% that rounds off to 100, such as 99.6. If it was claimed to be 100.0% pure, it would have to be 99.95% pure or better.
  5. That's pretty cheap Patrick! I called a local pool supply house for a price on the sodium sulfite you cited in another thread (Chemout), and it's the same price ($12/2 lbs) as Photographer's formulary , but no shipping! Thanks.
  6. Not to go too far off topic, but I've got a partially filled container of sodium sulfite that's about 25 years old. I haven't opened it lately but I recall it being in a plastic bag-liner inside the container, which is one of those heavy cardboard/fiber pail jobs. I think it was 100 lbs when I bought it, back when I was a mixin' fool.

    Is it still good, or even maybe good? Or should I just forget about it?
  7. When I used to buy Analar quality chemicals, an entire assay was given listing other compounds present down to five places of decimals. If sodium carbonate is listed as 100 % then this cannot be strictly true but sufficently pure for all practical purposes. The sodium carbonate I currently buy does not come with an assay but is clearly suffciently pure for photographic applications.
  8. That's a very good price, given that I paid more than $2 for a box of three pounds of washing soda not long ago. Now, the washing soda is about 98% pure, works fine in every photographic application I've tried, but it's (most likely) decahydrate, which means it's about three times the price (not counting shipping).

    Of course, I now have about a year's supply of soda, but I'll try to remember when I next need to shop. Did they have other photographically interesting chemicals, like metol, phenidone, hydroquinone, etc.?
  9. appears to be oriented toward cosmetics and detergents. Best look them up and scan their product list. They do have potassium carbonate, propylene glycol, triethanolamine and many other chemicals we can use, but I don't remember seeing any developing agents.
  10. Guys;

    At that price, I doubt that the purity is higher than 98%, and may be less. As noted on another thread, mining and purifying sodium carbonate is a big business. I know how hard it is to get these chemicals free of halides, so I question any purity claims.

    Read the comments on the other thread below.

    Ron Mowrey
  11. chemistry store is targeted to cosmetics?
    then all the products should be of high quality, maybe some halides but worth a try at that rpice.

    Their PG and TEA should be USP grade.. have to look again
    While their MSDS claims 100% Na-Carbonate I'd take it as 99.xxxx but probably good enough for photographic uses. Let us know how the test go
  12. Patrick - I posted this at the end of the other thread, but I'll put it here too.

    An MSDS is not a certification of purity - it is a safety guideline that the Dept. of Transportation, industrial hygenists, firefighters and other use to determine the safety associated with a substance. That 100% figure you see most probably means that the sodium carbonate does not have any other added ingredients and that for all practical (read - safety) purposes, is behaves as 100% sodium carbonate. Firefighters do not care if there are minor amounts of something in the sodium carbonate unless it would cause it to behave differently, such as when they spray water all over it. But a MSDS is not an assay of purity.

    You mention accuracy, but what about the error associated with those numbers? If an MSDS says 100%, is that 100 +/- 0.1%, or 0.5%, or 1.7%? We can't tell. That's where having an analyzed reagent or at the least tested to meet the criteria set out in the product specifications is better. Error limits are given to truly know what the error limits are - you can not really be certain that the error is equal to the rounding step, as you assumed above. It most likely is not.

    I've also seen assays on analyzed reagents come up above 100% - that just kind of reflects the nature of the chemical and the method used to determine the assay. It may not really mean the assay is wrong or bad, but it may be just as accurate as an assay that comes up a little under 100%. It's just the nature of the methods used...

    And it's not that the supplier is "lying" about anything. They are just following the guidelines set out by their industry, and those guidelines may not match the guidlelines that the photographic industry follows.

    All that said, enjoy your bargain!

  13. Kirk;

    That was right on.

    Different industries have different standards. What is right and useful and uncontaminated to one, might be bad in another.

    I have tried to make that clear myself in my posts.

    If people wish to use cosmetic grade, or food grade or 'pool grade' chemicals in their photographic chemicals, let them. I think that you and I have pointed out that it may not make any difference, but then again, it might. And, if it does, they have no cause for complaint.

    After all, you can hammer in a nail with a wrench, but it wasn't designed for that purpose either, but it is heavy and has a handle, so it 'kinda' meets the specs for a hammer.

    Which, when you look at it, is just what I've been trying to point out when it comes to choosing chemicals.


    Ron Mowrey
  14. So, Ron, what do you ask for when you want the utmost quality of sodium carbonate? How do you know when you have gotten it? More to the point, how do you know when you need the utmost purity? I am presuming that most of us are not doing quantitative analysis on every chemical we buy and are not using our chemicals for quantitative analysis of other chemicals. In practical photography, if it looks like sodium carbonate, acts like sodium carbonate, and has no measurable unwanted reactions, then for my purposes it IS sodium carbonate. If it is not, at least it does the same job, and at much less than $5 a pound.

    When the manufacturer specifies 100% anhydrous sodium carbonate, I take that to mean that the actual percentage rounds off to 100 and is within 1 unit of 100. If that statement is not true, you can hold the manufacturer responsible for whatever damage the difference causes.

    The Chemistry Store does not specify any limitations on what their product is to be used for. They sell many products beside raw chemicals, and from those products one may judge that they cater to people who make food, cosmetics and detergents.
  15. Patrick;

    Since I rely mostly on prepackaged chemistry with the exception of some esoteric color chemistry and B&W printing from time to time, I can't answer your question definitively.

    Kirk and others in this thread and the previous one that was referenced above have made very definitive statements about purity.

    I keep repeating that my purpose was to heighten awareness and spark discussion on a potential weak point in scratch mixing developers. It has done just that.

    I buy from Photographers Formulary, trusting that they supply a photographic grade set of chemicals. So far, after three batches (no, I don't know if they are truly batches, but they came from three orders over the period of about a year) and starting the fourth, I find good repeatability in my color printing work, and in my B&W paper developers. I do have a slight amount of sediment that I let settle out before use, and I don't use the developers for film. From the tests I am able to run, their sodium carbonate is free of halides for all practical purposes, and I can repeat Dektol very well, thank you, except for the sediment mentioned above.

    OTOH, there is a chemistry supply firm here in Rochester that deals with very high purity chemistry. I may investigate their analytical grade if I need to. But, I won't use 'pool grade'.

    I will also weigh things in grams or grains, and not use teaspoons and tablespoons. I guess I'm too much of a purist, and have seen too many things go wrong using approximations.

    If I'm going to develop a $2 sheet of color film or a $1 sheet of color paper, I want to be sure that the results are right on and repeatable, and that others can repeat my work if necessary.

    I have listend closely and objectively to what Kirk and others have said, and I have developed a healthy respect for their POV regarding standards and purity (or lack thereof unfortunately, or confusion therein... whichever way you want to look at it)

    Since I have nothing to lose or gain by whatever anyone does here, only they do, I say that you should use what appears to work. If it fails, does something unexpected, or whatever, it is on the shoulders of the user(s). I will continue to use what works for me and if it fails, I will take issue with the company supplying me. You, OTOH, will have short shrift if you try to complain to a pool supply company that their sodium carbonate ruined your photos of your newest grandchild or something like that.

    Ron Mowrey
  16. I had a similar discussion with some friends in 1973 after I wrote for Petersen's Photographic about using volumetric measurements. I demonstrated the consistency of such measurements. The mean deviation of ten teaspoons of several chemicals was less than the accuracy recommended by Kodak of a balance or scale for weighing chemicals for developers. They went out and bought analytical balances. I will never convince you that the accuracy required of black and white film or paper developers is not as great as some of us would believe. But tell me, are all the formulae in "The Darkroom Cookbook" in any one category so much different from one another? I see a number of developers that differ from one another by more than the error that would be introduced by 98% carbonate, yet they are claimed to give the same results.

    You might go so far as to ask Photographer's Formulary about the purity of their sodium carbonate.

    I am not about to tell any amateur or professional photographer what he must do, but I see no harm in telling all what they can do.

    By the way, the article "Salt to Taste" is in Volume 23, #1 of Photo Techniques and is still available among the back issues.
  17. Patrick;

    I have had problems desigining photographic coatings or processing solutions, and I have seen others with the same problems, when the experiments were designed improperly, when tests were not repeated, or when they were repeated improperly. I have left out tests that I should have run, and seen others do it as well.

    What I learned was that you can prove, or disprove, just about anything with film or paper by running the appropriate or inappropriate test. I see print tests claiming sharper images, but what I see sometimes is contrastier images which can be mistaken for sharpness. I see claims for finer grain, but it is really an increase in sharpness that makes the grain look finer, but in other cases they claim more grain, but again it is sharper grain due to increased overall sharpness.

    So, basically, I rely on my eyes supplemented by intrumental tests. A real proof of sharpness or grain, for example, cannot be just stated by comparing two pictures of a chart. You should have appropriate tests run to verify that the contrasts are comparable before you make the statement. (that is a generic you, I'm not pointing any fingers) In many cases, this involves very sophisticated equipment and these tests are also hard to run.

    In regards to the standard deviation of tablespoons, I'm just making the comment that measures by that method, done by one person, on one batch of chemicals, might work and in your case did, but if another batch has a different crystal habit (powder vs spheres), there can be over a 50% difference in packing density and therefore weight. You may never have run into that particular problem, but I have using a powder vs granular materials. The person trying to duplicate a 'spherical' measurement with a powder could be off by over 50%. A person who uses spherical chemical particles, vs an ellipsoid particle could be off by 20% or so.

    One of the most famous of all chemical mixtures compounded by volume was gunpowder. However, IIRC, the makers recommended pulverizing to a powder, each ingredient, in its own mortar and pestle before measuring out the powders by volume, because in those days the making of uniform crystals was a primitive science. Lump charcoal, sulfur, and saltpeter were well known, but purifying them was not, so they crushed them to uniform powder and only then were they able to get repreatability.

    So, unless everyone is using a mortar and pestle, and crushing materials to a uniform powder, I doubt that everyone will get uniform results from volumetric measure due to variation in the chemicals supplied.

    I have gotten crystalline phenidone, and powdered phenidone. I have crystalline sodium sulfite and powdered sodium sulfite. I have potassium bromide in large cubic crystals and in small cubic crystals like table salt. Which one is volumetrically the 'correct' amount?

    Therefore, although it is possible, over the long term I doubt that it will work for evreyone in every case with every chemical. There are just too many variables.

    I say, good luck to them and I hope that they don't ruin any valuable pictures. I will stick to gravimetric measures. Sorry I can't agree with you.

    Ron Mowrey
  18. I don't know if you've noticed, but every time you buy a pound of any photo chemical it comes in the same size container and has about the same empty space. Now if you are smart, you will measure the whole pound in a graduate or kitchen measuring cup to find the actual volume. If you know how many ml are in the whole pound, you know how many grams are in a tea or tablespoon full by a simple calculation. If you are making black and white developers, you will soon learn that when a formula in some book specifies something like 45.25 grams of something, that number was not arrived at by scientific calculation, but was the number that "worked" in the original formula and could just as well been 40 or 50.

    Though developing agents may be more critical because of their smaller amounts, you will be able to find a volumetric measurement that "works" and will continue to work the same way every time you make it up as long as you use the same batches of chemicals.

    Please note I deal only with black and white. I am sure there are tolerances in color developer also, but I don't know what they are.

    The way to find out what tolerances there are in black and white is to weigh carefully the ingredients and mix a batch of your favorite developer. Then do a series of experiments in which you vary the amounts of ingredients according to an experimental plan such as "magic squares" and compare the results of each test with the original. You will be interested in grain, resolution, film speed, curve shape, and if you are Ron Mowery, in proving Pat Gainer wrong. (Couldn't resist the dig.)
  19. Patrick;

    You of all people here, having taken chemistry, should be well aware of the fact that the packing density of a chemical varies with crystal habit. I have also mentioned that I have 2 bottles of Sodium Sulfite (anh) on my shelf, one from Aldrich and another from Kodak. They are totally different in crystal form and probably density. I have not measured them to prove anything one way or another. I'm not interested in trying to prove or disprove anyone, as I weigh things.

    In addition, the chemical levels that I worked with were molar quantities adjusted to acheive the optimum ratio of chemicals based on extensive experimentation. That is why you use 800 ml of water, add chemicals, then dilute to 1 liter, so you have a measured molar concentration of chemicals determined by these experiments. I worked in both g/l and moles/l, and in some cases you will find precise molar ratios of ingredients when the weights look odd to you. In other cases, chemicals are adjusted to a molar level based on the seasoning or aerial oxidation effects. It would be far easier to work with molal concentrations for the average user, but it would not be as accurate.

    The reason I brought up volumetric vs gravimetric measurement, and have current information as well, is not to dig anyone, but rather is due to the fact that Science News has reported at least 3 times in the last few months on the effect of packing density on the shape and size of a given material. Recent research shows that previous data stating that spheres packed the most densely of all materials has now been proven mathematically wrong and oblate spheroids are now the most densely packing material.

    I was quite taken with the variations in mass that can be packed volumetrically with various particle shapes and realized that it could have a very negative impact on volumetric measurements as I see being mentioned on this forum.

    Empiricism can be used Patrick, but does not always work when others are asked to repeat the results. I didn't say it would not work, I said it does not always work. I know, having spent many years designing developers, fixes, hardeners, bleaches, and blixes. I am trying to heighten awareness to the dangers of some of these empirical, qualitative, and volumetric methodologies, not take pot shots at people or their ideas.

    Granted that probably more than 80% of my work was with color systems, that is beside the point really. The fundamental research methods are what are important. Also, the principles of photography in B&W and color are nearly identical as well. You do use an MQ for processing reversal color films for example, and you use antioxidants in color and B&W developers. I could go on and on, but basically, I learned to do factorial experiments and apply statistics to gain a full understanding of photographic processing solutions. Some of what I learned came from Grant Haist personally, with whom I worked for a while. He and I exchanged a lot of ideas on B&W and color processing.

    I'm sorry if what I have said has offended you. No offence was intended. I was and am trying to help scratch mixers get better results. If my suggestions go unheeded, there is no loss to me. If they heed you rather than me for whatever reason, that is also no loss to me. My position here is simply this. I will not knowingly give any incorrect or inappropriate advice to anyone. I will do no harm. I will not reveal any information given to me in confidence.

    If you can show in this thread or the previous one that I started, that I have gone against my principles stated above, I will apologize to all concerned. Otherwise I stand by what I have said.

    If, on the other hand, what I have said bothers you, and if you see any truth in what I have said whatsoever, then perhaps you should look to your own advice to others for possible or potential faults.

    Ron Mowrey
  20. "Recent research shows that previous data stating that spheres packed the most densely of all materials has now been proven mathematically wrong and oblate spheroids are now the most densely packing material."


    Isn't that the "M&M Theory"?
  21. Yes Lex, you have it right.

    And this is the fundamental problem with volumetric measurement of solids. It is going to eventually fail for someone.

    So, aside from chemical purity there is also the issue of measuring out solids by volume rather than by weight. The actual amount measured depends completely on particle shape.

    Ron Mowrey
  22. I'm a believer in following what's known as "best practice". If you have the ability to weigh stuff accurately, why not do it? If you don't, you do what you have to do. Also, if you have a method that has worked in the past, and appears to continue to work, why worry. There are too many things that concievably can go wrong to fixate on the purity of a few chemicals. If you don't think so, you just don't have a good imagination. The hobby can be enjoyed on many different levels. Mine is fairly technical, but artistically iccky. Nor do I spel two good. And you don't have to be consistant. I'm generally fussy about fresh materials, but I just posted an image in the classic camera forum that I shot today on Plus-X that expired in 1977 and was sitting out in the bright sun at a flea market for most of a day. I doubt that film knew if the developer was weighed out on my Mettler, or the bathroom scale, much less where the carbonate came from!
  23. I thought the problem with weighing chemicals was they pick up moisture. You end up weighing water. OTOH volume measurement doesn't have that issue. It's not exactly hard to weigh a sample when you buy new chemicals and check how much they weigh.
  24. Robert - I don't know if that is a common misconception, but it is a misconception. Chemicals most certainly will change density as they absorb (or loose) water or react with other agents, such as carbon dioxide or oxygen from the air.

    Looking up in a CRC Handbook of Chemistry and Physics (or your favourite chemistry handbook) what the density of compounds at different levels of hydration, and you will see the density most certainly changes, and so therefore does the volume of a given amount.

    Here's an example - I'f you've ever looked at the mortar in an old building, you will probably see that it is cracking or even falling apart - this is because the lime in the mortar is reacting with both water and CO2 and it is changing molar volume (or loosing water depending on the enivoronment it is in). There are still the same number of lime molecules as in the mortar when it was made, but because it is aging and reacting with other things in it's environment, it is changing chemical composition - if it is in a moist evironment it is becoming limestone. This new compound has a different crystal habit or density, and the mortar expands and starts to crack and fall apart. The volume most certainly does change.

    I'm with Conrad and Ron. Using volumetric measurements is interesting and could be used in a pinch, but why not minimize any errors you may have by simply weighing out your chemicals? There are electronic scales nowadays that are soo inexpensive (I guess we can thank the illicite drug trade for that) that there is really no excuse not to be able to wiegh things out.

    And are all you teaspoon photochemists really wieghing out every chemical you are buying when you first get the bottle, or are you guys just taking the word of someone else as to the density of these compounds? And what happened to everyones concern about being poisoned by some of these things - like pyro and other developers? If you want to minimize exposures, you will probably want to avoid dumping all your new chemicals out of the bottles and then assuming the stated amount on the bottle is accurate to make your volumetric measurements. It's just too much fussing around when there is a simpler and more accurate way to do things, just weigh it!

    Rube Goldberg, where are you?

  25. Robert, Kirk;

    I'm kind of hard pressed to think of many chemicals that absorb moisture out of air so rapidly that they affect normal weighing operations.

    The only two used photographically that come to mind are NaOH anhydrous pellets and certain hydration grades of Sodium Thiosulfate ( I forget the grades now, I'm sorry ). You can see the weight change of a sample as you watch the balance with these two, but you need a RH in the room of about 50% or higher to see it.

    The thiocyanate salts are hygroscopic, but act very slowly in absorbing moisure. Carbonate and sulfite are even slower IIRC.

    Anhydrous copper sulfate is also subject to absorbing moisture from air, but it is so hygroscopic you generally have trouble even storing it anhydrous. I have rarely seen it anyhdrous. It is not a common photographic chemical.

    Aluminum chloride is another. It actually begins to react violently to air when you open it up, as it reacts with moisture and liberates HCl. It is not used photographically, only in organic chemical syntheses. Even with its high reactivity, I was able to weigh it out and use it with accuracy when doing syntheses. I just worked fast.

    My main concern is not with absorbing moisture rapidly, but rather with the variation in density due to variations in crystal type and purity of chemical depending on source.

    Thanks for the post Kirk. Good information. Conrad, you have a vaild point, as I said above. Use what works. But, I added that volumetric measure or incorrect measure may bite you sometime. It has bitten me.

    Ron Mowrey
  26. Ron,

    You are not offending me. This is supposed to be a good humored discussion. You can make fun of me if I can make fun of you. If we were talking face to face, the situation would be different.

    The fact remains, I know what tolerances I have in my solutions for errors in measurement and you do not. I take advantage of those tolerances to make weighing and mixing quicker and yet just as effective. If you were to measure the volume of each pound of each chemical you buy, the matter of particle shape would not come up.

    As for density changes due to water, you did not say whether they were due to change in weight from taking on water or to changes of volume. You know, I am sure, that the volume of a solution often changes very little with addition of soluble chemicals. If water of crystallization is between molecules of a chamical, the volume of a given amount will not change as the water is taken up. One experiment you can easilly try is to heat a known volume of, say, monohydrated sodium carbonate until it is reduced to anhydrous form and note the change of volume, if any. Certainly the reverse change would apply when you go from anhydrous to monohydrate.

    The only trouble I see with many of your assertions is that they are based on your theory rather than practice. I don't care if you believe that the formula you weigh to the specified milligram is the only one that will work properly, but if you are going to preach that as fact, then demonstrate it for the rest of us. You will have to draw the line somewhere, though. If as Kodak says, + or - 0.1 grams is close enough for most formulae, then I can use my spoons to get a consistent formula that works the same every time I mix it. The only proviso is that I measure the volume of the whole batch before hand. You also know, I'm sure, that it is common custom to keep solutions of things that must be measured in such small quantities that ordinary balances are not sensitive enough. These do not have to be water solutions. I make a 1% solution of phenidone in propylene glycol that is very useful. It keeps very well, as the glycol does not ionize it.
  27. Patrick;

    If I take 1 g of Hydroquinone crystals (needles usually) and measure the volume, then crush the needles, the volume is substantially less than before. The packing density is higher, but the materials density is the same. This is a fact. I can't run this experiment right now, as I have negatives drying in the darkroom, but I guess I may have to to prove a point if you really do disbelieve me and have forgotten your chemistry.

    Basically, if you buy 1 lb of HQ as needles, measure their density, and do nothing more to it but use it over a few months, by a volumetric method, you will probably be fine. Then you order another batch and use the same density value, but this is not the same size needle, or is tabular, then you have a problem. You have to come up with a new density value. This is fact. Do I have to run the experiment? I don't have the equipment to recrystallize HQ and filter and dry it Patrick.

    Packing density depends on the degree of shaking a material has in the container measuring it, as well as the shape of the container. This is a fact. I suspect that needles would measure poorly in a teaspoon, but much better in a cylinder. That latter is not fact, it is opinion, but the first sentence about shaking is fact. It is based on the fact that needles tend to take any orientation, shaking reorients them more optimally, and trying to smoothe off the surface of a spoon of material with its broad surface may scrape off much more than from a cylinder. IDK, just a hunch.

    There is much to be said for the Edisonian or empirical method of research Patrick, but photography is quantitative, not qualitative. So, the formulas that you have published are fine formulas, I'm sure, as attested to by many people.

    The methods of mixing them by gravimetric measure and the use of 'pool' chemicals are what I question. These >may< cause problems for some people. Weighing is much more accurate and using photograde chemicals is much more reliable. In addition to which, by using photograde chemicals you have a company to fall back on if there is any fault with the chemistry.

    If you weigh your chemicals to start with to get a benchmark density, and then you measure them volumetrically, it means that you have the scale, and the skill to do gravimetric measurement, but use a method that is less reliable for some reason. I really don't know why anyone would do that.

    So, I guess I have to go back and 'prove' to you what I learned in freshman chemistry lab. You shouldn't have to ask me for proof Patrick, you should know this is factual information.

    As for chemical tolerances, I have no idea what they are in most developers, but I don't want to take the chance of error. Film, chemicals, and my time are valuable to me. I have two balances in my lab, and I can prepare the dry ingredients for a one liter or two liter batch of developer in about 10 mins or less. I use the two balances for two ranges of weights. One is used for milligram quantities and the other is used for gram quantities. Of course one balance can be purchased for both, but this is what I have. If I make an error that I know about, the chemical or developer goes into my waste.

    As for changes in volume with water of hydration, this is another fact, and is why a container bursts when a chemical in it hydrates. Sometimes it can be spectacular as with hypo which can gain up to 7 moles / mole of water or more. In fact, it can turn into a syrup on standing and burst the container. I have seen this happen with several hundred pounds of hypo. It required shovels to clean the loading dock up. No, it wasn't at EK. They have more sense.

    Sometimes, volume increases as a chemical dehydrates but the density goes down. You see this when you heat copper sulfate hydrate and it turns into a light white mass with higher volume, but less density. Of course, you can pack this down into a smaller volume by crushing the new crystals, but as you do this, it rehydrates and forms the blue material thereby changing density and forming an actual mixture of hydrated and unhydrated salts.

    Sodium carbonate (anh) can sit for a year or more in a closed container without hydrating appreciably. As it hydrates or as the hydrate dehydrates, density and crystal habit both change. You know that as well as I do if you took Freshman chemistry.

    So, do you want me to run these simple elementary experiments or do you accept established fact taught to both of us in chemistry?

    Another individual has already established factual information here on matters of purity that you disputed. He has shown that 100% pure materials may, in fact, be less than that in purity as long as for the intended purpose, the chemical acts as if it were 100% pure. Shall I now go to the lab and weigh out some HQ and measure the volume, then crush it and re-weigh the volume and express the % difference here? I think not. Logic and chemical knowledge will tell you that I'm right. Remember the M&M example above? Apply it here Patrick.

    Ron Mowrey
  28. Ron,
    I don't need you to show me what I know, but I think it would be good for you to ponder a bit about what you do not know by your own admission. If hypo crystals swell up, that simply means that you cannot tell any better what weight of hypo you have by weighing it than I can by spooning it out. In fact, under those circumstances you don't know how much water was absorbed.

    You can believe if you want to that the fellow who came up with the recipe you use actually arrived at it by weighing individual amounts of metol, hydroquinone, borax and sodium sulfite (or whatever), varying each amount a milligram at a time until he reached perfection, but I'll bet a nickel he did not. Sometime, try making D-76 with the standard amounts of everything but half the amount of sulfite. You might learn something useful.

    I have measured hydroquinone both by spoonful and by weight for over 30 years. I have never thought of trying to obfuscate matters by grinding it in a mortar. If I deem a measure to be critical, I will weight it. But that is usually only when I want to report accurately my results, and my formulae generally use integer amounts. No one will convince me that 2.1 grams of metol and 4.9 grams of hydroquinone will be noticeably different from 2.00 and 5.00 in D-76.

    I also have 2 scales, one measuring to 0.1 grains and the other to 0.1 grams. When I am making stock solutions for experiments, I weigh the solids. If it is reasonable to do so, I convert to volumetric measure for the benefit of others.

    If you think photography is that exact in practice, you have delusions of grandeur on its part. None of the manufacturing tolerances of the film you buy are as close as you would have your measurements of weight, especially when you are measuring something of which you do not know the consistency. I still suggest you ask P F what it is they sell for sodium carbonate.

    Also, the fact that the MSDS quotes a NIOSH number had better have something with the ingredients quoted. This assay is not done by the seller.
  29. Patrick;

    6.76 g of crystalline cubic NaBr is 5.0 cc after vigorous shaking to settle the solid.

    6.70 g of powdered NaBr is 4.0 cc after vigorous shaking to settle the solid.

    This is a 20% difference. I'll do more when I get the time. I don't have a mortar and pestle or a ball mill, nor can I waste chemicals for this demonstration of the obvious and elementary.

    Oh, I took crystalline NaCl and Na2SO3 and compared them to powder, and there was little difference. This was due to the fact that these two compounds are almost powders to start with, merely emphasizing the point that this method is highly variable from compound to compound, and perhaps even batch to batch.

    All transfers were with dry powder funnels to insure minimum loss of materials. Samples were weighed before and after the volumetric measurements to insure accuracy. Materials were packed by shaking, then measured in volume, then tamped lightly with a plastic tamper to verify the solid surface. Measurement was done in a glass graduate cylinder.

    Ron Mowrey
  30. Ron,

    It's obvious that you and I are more concerned with precision than Patrick. That's fine - he has demonstrated to himself that his methods achieve acceptable results for him. That's great.

    Since we've resolved that issue now, I was wondering if you had any info on the methods that companies like EK used when packaging dry products. I assume they either have fancy automated scales that measure out amounts and add them to the packaging, or more likely they use bulk density measurementes to make volumetric measurements. Or perhaps a combination of the two methods. Could you discuss this? Also, if you have any info on the limits on the variability of the amounts that can be added and still be acceptable to the QC department there, that would be interesting.

  31. Kirk;

    I cannot discuss some of the things you ask for two reasons. First is that I don't know some of it, and second, a lot of what I do know is confidential.

    That said, I can say that the measurement is automated using large mixing equipment and weighing is by means of strain gauges. A quantity of solid or liquid is allowed to flow into a container and a strain gauge is used to verify total weight. Any over or under weight material is rejected. The tolerance is based on the tolerance of the strain gauge used.

    Measurement or movement of some chemicals is under an inert dry atmosphere.

    Mixing can also use a ball mill for reducing large particles and for mixing several ingredients.

    On a large industrial scale, there is little use for volumetric measures. They are less reliable AFAIK than gravimetric measures.

    Published formulas differ from pre-mixed formulas usually only in the addition of sequestrants and anti-caking or drying agents to prevent problems during storage or mixing.

    In-house formulas are virtually identical to those used in manufacturing. KRL and the testing divisions establish the permissable limits on a given ingredient and on given impurities.

    Average testing of a new chemical or formula takes longer than you might think. Just the seasoning tests for a new developer take months and consume large quantities of processing solutions and film or paper and require a lot of analytical chemistry. This is one of the tests used to determine the permissable limits of a given chemical, and to come up with the actual required level to sustain a constant concentration in a normal replenished process. It is also the method used to determine shelf life and capacity of a given solution.

    For example, if a developer uses 0.512 g/l of NaBr as a hypothetical example, then all of the films with reported development times and speeds require that level for correct speed and contrast etc. As bromide goes up or down, the different films respond differently. It is only the 'check' developer that is certified to give the correct overall results. Other concentrations of bromide will respond unpredictably with every film or indeed with every different emulsion # of a given film. I have actually run that type of test many times and proven it to my satisfaction.

    The reason for this variation in response is due to the various halide ratios in films and papers, the addenda, the level of silver coated, and etc.

    The final test though is that a developer should yield a constant speed, contrast, dmin, dmax, MTF, and RMSG with every batch of every film with respect to the given films release aim. And, the results should not vary whether the chemistry is fresh or seasoned. The limits imposed by the strain gauge are further restricted by these factors. If the film imposes a tighter limit on tolerances, the tighter tolerance wins and then a more accurate measurement is adopted. This might be the use of a solution of the chemical being weighed out rather than the solid chemical. This increases the precision of weighing out with small tolerances.

    I hope that helps.

    Ron Mowrey
  32. Maybe I can summarize, perhaps a little whimsically, what we have discovered here.
    Rowland Mowery says I cannot use volumetric measures of solid materials with sufficient accuracy because I do not know the particle shape of a particular batch. I say I can eliminate particle shape or size for any one batch by weighing a given batch and measuring its volume. I say also that I know from experience, and from observing a number of different formulas, that all make the same claims, and that there is considerable tolerance for error in making up these formulas.
    I claim that if I know the tolerance for error in measurement of weight of the constituents of a given formula, I can relieve myself and others of the burden of weighing everything to the milligram out of fear that we might make it fail to work. OTOH, I might find that some formulas do in fact require such accuracy. If I find one in my own research, I will let you know.
    If NaOH and some others turn into a puddle after sitting in humid air, then we are both out of luck, whether we use weight or volume. If I am foolish enough to grind up my hydroquinone into a fine powder and then wonder why I don't get the same weight per volume as before, then I really should buy ready-mixed everything. I would probably be the same kind of Boy Scout who knew all his matches would work because he tested them.
    If anyone would like to continue this discussion off the forum, my e-mail address is
    (Moderator's note: e-mail address modified slightly to ward off spambots.)
  33. Patrick;

    Interesting summary.

    Here is a reference.

    Science News Vol 165, # 25, P 397. Johannes Kepler in 1611 first referred to packing of spheres etc.... In this experiment they observed a 3% difference between spheres and ellipsoids. They cite other references.

    One last note then from me.

    Since a container of solid is subject to shaking and therefore settling of finer particles to the bottom (as you all know from eating potatoe chips, the small chips are at the bottom of the bag), the smaller particles are at the bottom of the container.

    We know that the small particles settle by moving through the matrix of larger particles by means of the voids between the particles.

    Therefore, the size of particles in any container of materials is graded with large particles at the top and finer particles at the bottom. This means that packing density can vary from the top of a container to the bottom.

    If you don't believe me, keep note of particle size of a larger crystalline material and you will find it finer and finer the closer you get to the bottom of the container until finally the bottom will consist of a lot of dust.

    This is particularly true of HQ for example which forms rather fragile needles when compared with NaCl with robust cubic crystals. Therefore, I don't have to crush my HQ, UPS does it for me during shipping.

    To demonstrate this to yourself, get a glass jar and fill it 1/2 way with common brick sand. Bang on the side of the jar with the palm of your hand and as you do, you will see larger particles appearing on the surface and if you watch long enough, you will see the finer stuff moving to the bottom.

    I have been searching for the reference in Science News for that experiment as well, but I cannot seem to find it. When I do, I will post it as well. They ran the experiment with colored balls of different sizes.

    Have fun.

    Ron Mowrey
  34. Once again, food to the rescue. My wife opens the bridge mix and pours out the larger chocolate nuts and caramels that have found their way to the top. I then pour some for myself. All I get are the stinking little chocolate raisins that settled to the bottom. I don't like raisins. OTOH, I can shake my bottle of bromide all I want, and the giant lump of the stuff rests on the bottom every time. When I need some for developer, I pound a big screwdriver into the lump and break off a piece. That's not so bad, but it's PPD that really annoys me. It comes in odd sized pieces that are too large. I don't like to grind it, due to the toxicity (sp?). Note to Photographers Formulary- buy a bigger hammer or a ball mill!
  35. Another food example: a can of mixed nuts. The Brazil Nuts are always on the top. Always. The top of the mix will also have the filberts and other large nuts. The bottom will have the broken pieces of all the nuts.

    A scooped portion from the top will therefore have less weight and more air than an equal volume scooped portion from the bottom.

    As to the rest of the thread, isn't there an old song about the cowboy and the engineer? :)
  36. I'll give you an opposite example.

    If you make a polydispersed emulsion, one with a wide range of grain sizes, and chill it to set the gelatin, all of the large grains settle to the bottom of the container unless you stir it constantly.

    This is the effect of particle 'weight' not 'density'. Gravity pulls the heavier particles to the bottom of a solution when a solid is suspended in a liquid like matrix.

    Therefore, stones settle out in mud, they don't rise to the surface.

    In a similar manner, very large lumps, as you find in your KBr sample, can fall to the bottom or rise to the top, depending on size of the lump and the aggregate size of the rest of the grains.

    Therefore, the entire process is unpredictable and can (not will) lead to problems.

    Yes, the cowboy and the engineer.


    Ron Mowrey
  37. Let me restate my position. It appears that many of you are assuming that we need the utmost accuracy in our measurements. I agree that in those rare cases that we do, then we should weigh as accurately as possible. The problem is that there is a limit for every person's lab to the precision that can be obtained. OTH, there is in almost every one of our mixtures a sufficient tolerance for variance that we do not need an analytical balance. In every use of bromide, for example, that I will encounter, a % solution will be handy. Some use a saturated solution. You add it drop by drop until you get the desired result. When I make a bleach for sepia tonong, I can use a spoonful of KBr, a spoonful of ferricyanide, a little carbonate and some water. If it is weaker or stronger than the last time, who cares? It will be used until the job is done. Print developers are the same way. If they start out very precisely measured, the first print through changes all that. If you believe that black and white developers for negatives require more precision, don't let me stop you. But you must realize that the very same logic that you use to explain why you must weigh things accurately says that you cnnot get an accurate measurement by ANY means because the water of crystallization is not exactly known after you open the container, and many times not even before you open it. Deliquescent compounds are a worse problem. If you are bent on getting a solution of certain properties, you really need a way to test those properties. No matter how you go about measuring the ingredients, you stand a good chance of not getting the result you expected simply because you depend on the statement of someone else about the purity of the ingredients.

    If you do have a way of testing to see if you got what you want, then the accuracy of the initial measurements becomes less critical. You develop a procedure of titration or something similar. If you are a cook, you taste-test as you go along.

    Peace, my brothers.
  38. Today, I added a dash of hydroquinone to my xtol. Not having a 1/10 teaspoon measurer on hand, I dumped out a 1/2 teaspoon of crystals on quadrille paper and scraped it into a rough line. 2-1/2 of the approximately 12 squares went into the 210 ml of 1+1 xtol; the rest went back into the bottle. Not to make a mockery of Ron's point about precision; I just didn't have anything else on hand to measure with. (More on the xtol+hq experiment soon; I'm not yet happy with the results.)
  39. To all who may read this;

    Patrick Gainer has come up with some very outstanding and unique formulas for processing B&W materials.

    While reading this forum, I observed a number of people using chemicals or practices which could possibly cause them some problems. Among these were using uncertified chemicals and volumetric measures of solids to mix up Patricks formulas and the formulas published by others.

    I felt that you should all have a chance at producing the optimum results with all formulas, not just Patricks, and so I began the previous thread on this subject. Not in the interest of hurting anyone, but in the interest of improving quality.

    I have tried to raise your standards, so that you are aware of the possible pitfalls in using these uncertified chemicals and measuring methods. I am not saying that they will cause problems, but that they can cause problems.

    By all means, use what works for you, but if it fails to live up to the potential built into the product (film or paper) or processing chemistry (Patricks or someone elses), then all I can say is - I tried to make you aware that something like this could possibly happen to you.

    There seems to be quite a division of opinion in the readers of these threads. No matter what your opinions are, please read up on the subjects discussed here, think about them with an open mind and then do what you believe to be the best for obtaining quality photographs from your darkroom work.

    Best of luck to you all.

    Ron Mowrey
  40. In case you hadn't figured it out, my finger got lazy on the shift key. My e-mail address should have read
    I too have resorted to shaking lumpy chemicals to get the small particles at the top. You really must arrive at a philosophy of precision and accuracy that is logical. Mindless scrupulosity is not much better than mindless disregard. They can both lead to mindless arguments over non-issues. I won't call anyone stupid, but I might use my father's favorite description of me:"Worry wart!" But what did he know? He was only a Professor of English Literature.
    (Moderator's note: e-mail address modified slightly to ward off spambots. Insert the @ symbol in place of "_at_".)
  41. Here is a possible way to prepare solutions of chemicals that have unknown amounts of water of crystallization. Prepare a solution, measure its specific gravity, and refer to the tables in the CRC Handbook of Chemistry and Physics. There, for most of the worrisome compounds we must use, you will find tables of anhydrous weight percent (Grams of anhydrous solute / 100 ml of solution) vs specific gravity. Find the actual weight percent of anhydrous solute corresponding to the specific gravity you measured. You may then dilute the solution to the desired concentration or add more solute. As you see, it is easier to start high and dilute.

    The tables show 4 places after the decimal. As to whether you can measure the specific gravity (weight per unit volume) well enough to take advantage of 0.0001 unit of specific gravity, I do not know, but that is one of the problems you must solve for utmost accuracy of measurement of salts with unknown water content. I would say that if you can measure 100 ml +/- 0.01 and grams to +/- .01, you should be in good shape. There are some float guages for measuring specific gravity that may be of sufficient precision to suit your purpose.

    The foregoing method presumes that the only uncertainty in the soluble matter is the water content. Insoluble matter will settle or can be filtered. Foreign matter that is soluble will cause inaccuracy.
  42. Patrick;

    Hydration with most chemicals is a rather slow process except as I noted previously with the examples of Hypo and Sodium Hydroxide.

    Therefore, gaining (or losing) weight by this method is relatively slow, and not usually a problem. For Sodium Carbonate, the error would be on the order of about 15% going 100% either way from anhydrous to hydrated, or vice versa. Under conditions of 75 deg 50% RH, this would be a very slow process for virtually every chemical except as noted. Hypo or NaOH will change in weight on a humid day as you watch the balance. Most other chemicals will require hours or days in the open before you see a change. In closed bottles, they reduce the humidity of the air in the bottle and then stop. This is a miniscule amount of air. Remember that theoretically, 1 mole of water occupies about 22.5 liters as a gas and weighs only 18 grams. (If you could get STP conditions to perform this experiment) Considering the amount of water present even at 100% RH, in air, the amount of water is so small in the closed container, it is insignificant.

    For all pracitical purposes, you can just about ignore weight changes due to hydration / dehydration effects except for hypo and NaOH.

    There are some organic chemicals that absorb moisture rather rapidly as well.

    Ron Mowrey
  43. I believe the original premise (not mine, though) was that we do not know the state of hydration, that we cannot trust the distributor to be truthful, and that we must weigh rather than use volumetric measurements. When I said I bought 100% sodium carbonate, I was told this was impossible. Have we now come to a consensus that maybe we need not, or perhaps cannot, be so accurate after all?

    I left one measuring cup of the sodium carbonate that I bought as anhydrous on my balance with the weight zeroed out at 408 grams, Pyrex cup and all. After a few hours it had picked up 2 grams of weight. I think those 2 grams were very near the surface. Nevertheless, there is no measurable change in volume. If I were to mix the whole amount with water to a certain volume, I would get the same concentration after any number of days as I would have at the start.

    Just keep in mind that methods are available for preparing solutions of known concentration in spite of deliquescence or unknown state of hydration. Any developer solution that you concoct by any means whatsoever is subject to test for each of its characteristics. If it's characteristics are consistent, don't worry about whether you used measuring spoons or an analytical balance to measure out the components.

    For every developer I formulate, I could mix the original by the spoonful, then weigh out a different set of the same volumes and publish those weights to the nearest 0.01 grams. If I then made another batch using the accurate weights in place of the spoonfuls, would I find a practical difference in performance? By practical difference, I mean a difference between H&D curves. Any one of you can perform this test. I would be interested to hear of some results.
  44. Patrick;

    In my original discussion, I never brought up the subject of water of hydration. I was pointing out that chemicals to be used for pool pH adjustment (among others) were 98% pure and we didn't know what those impurities were.

    I and others, pointed out that they might be halide ions, bicarbonate, or just inert materials such as sand.

    Water of hydration is important however, in that pool chemicals probably don't have an assured assay on that front either, but I never brought it up, as water is the one true 'inert' contaminant of any chemical used commonly in photography.

    It will change the 'assay' on hypo by a huge factor, as well as sodium hydroxide, but as for sodium carbonate, well, 2 parts in 408 is very small. Thats about 0.5% in several hours. If it takes you that long to weigh your chemistry out, then you have a problem. After it is weighed out, then there is no problem. If the lid is put back on after weighing, then there is no problem.

    So, under normal circumstances, with most chemicals, hydration is not a significant problem. Storage in glass or plastic containers with tightly closed lids is no problem. That is why I never worry about this problem, nor did I bring it up on my own. You did. Your own example above shows that it is a non-problem.

    If you are worried about hydration, then order the chemical in the maximum hydrated state, and use it. Then there is usually no problem at all. Worry more about purity. For example, Na2CO3.H2O that is 98% pure still contains 2% impurity, which is 10X greater than the hydration experiment you ran. If it was halide or sand, or simply sodium silicate, that impurity would still cause a greater error in measurement than your hydration example.

    Oh, and don't forget that even you have admitted that your samples have different crystal sizes and that you 'select' your material from the bottle. Therefore, since I have shown a rather large 20% error depending on the use of crystalline vs powdered NaBr, there is still the worry of using volumetric measure.

    Most compounds change crystal habit during hydration. You would not observe that readily with a change of only 0.2% in your experiment. It may only be a surface coating on the surface of the top crystals in the container.

    Ron Mowrey
  45. Don't forget, I said that weight included the Pyrex pitcher. I suppose that if the weight had not increased, I could say I probably had washing soda, the decahydrate. The fact that it did increase with a very small part of the volume exposed at the surface indicates it might be anhydrous. Or maybe it was not Na2CO3 at all. I have only the distributor's word for it and the fact that it works in formulas where I use it as if it were anhydrous sodium carbonate.

    I think that if you believe that what you get from P. F. is significantly purer photographically than what you get from hTh as pHPlus, you could at least ask P. F. their opinion on the subject. The argument that weighing such chemicals each time is better than spooning them after determining the weight per spoonful depends on knowing what you say you cannot know. If you do not know the water content or the nature of the inert ingredients, what good will it do to weigh to the milligram?

    If you do not know the tolerance to error in measurement of each compound in a developer, how do you know you can even make a successful batch by ANY means?

    How do we know that those developer formulas that specify weights to the milligram didn't get that way simply by converting from grains to grams without rounding off? How do we know that someone like Pat Gainer didn't concoct something by throwing in a spoonful of this and a spoonful of that, and if it worked, simply weighed out spoonfuls of this and that and put those weights in the published formula?
  46. Patrick;

    You are combining three possible problems into one. This is confusing the issue.

    My original thread and question involved purity and purity alone. This diverged along the way to include from many parties, questions on water of hydration and volumetric measurement.

    I think that they all are important, and each contributes in its own way to error in photographic solution makeup. Of them all, water of hydration is probably the least of the problems except as I have previously noted for a few chemicals. That is why I have not really bothered with that issue very intensely in these threads.

    The real issues that bother me are volumetric measure and chemical purity, but as I have repeated, use what works for you.

    You have made up some excellent formulas and I just want to see them done justice, not hacked together.

    A friend of mine, Grant Haist, wrote several books on B&W and color photography. In his monobath manual, he describes a lot of formulas IIRC, and I assure you he concentrated on purity and gravimetric measurements. His close associate, Dick Henn came up with HC110 developer, and I'm sure he used gravimetric measure for his solids as well. For all I know, he used it for the liquids. Dick Dickerson and Sylvia Zawadski worked with Grant and Dick Henn as well. You might ask them their opinions if you know them.

    In all of my work, the only volumetric measurments that I made that I reccolect, in making up process formulas were: Benzyl Alcohol, Formalin, and Ammonium Hypo. These are all either liquids or solutions.

    A container of sodium carbonate (anh) contaminated with the monohydrate, is going to show an error in weight of up to 14% approximately, but is going to act just like sodium carbonate.

    A container of sodium carbonate with 2% impurity of NaCl can mess up badly in a B&W paper developer intended for a chloride paper. An NaI impurity of 2% intended for film developer can do much the same bad things, but you may only see it in microdensitometry as the effects might only be in edge effects.

    Packing denstiy varies with crystal form. Crystal form, as you yourself pointed out above, varies from top to bottom of a jar. My experiment with NaBr, although extreme, points to as much as a 20% error by volumetric measure.

    Therefore, I stand by what I said. I'm sorry that this makes you feel on the defensive about your recommendations and formulas, but I'm trying to help, not hurt. Please believe that and consider what I have said objectively. My goal is to try and raise overall quality.

    When I see complaints about mixing developers using dubious chemicals, I get concerned and try to do my utmost to bring possible pitfalls to the attention of people.

    Even published formulas leave out information or have errors in them. See the thread above about the fixer gone bad. We are close to an answer on that, but the result could have been quite dangerous.

    I wish you the best.

    Ron Mowrey
  47. So, would you say that a logical approach to the question of purity of chemicals is to find out how pure they must be to serve the purpose at hand, how precisely they must be measured, what purity is available, and with that information decide whether you need an analytical balance, a more economical balance, a powder scale, a kitchen scale, a set of measuring spoons, or all of the above?

    If a particular grade of a chemical specifies 98% purity with 2% inert ingredients, can we not find out from the manufacturer whether the 2% are really inert for photography?

    I can understand that for some purposes, the ratio between two chemicals must be fairly precise to get the desired reaction. Every time I have measured the ratio between 1/2 tsp ascorbic acid crystals or powder, and 1/4 tsp sodium bicarbonate, the ratio of actual weights has been close enough to that for producing neutral sodium ascorbate to make it not worth the trouble to weigh them.

    I have purchased ascorbic acid in crystal form and in powder form and erythorbic acid (isoascorbic acid) in powder form. The weight of one teaspoon of each of these is not enough different from the others to make it worth weighing them. Phenidone powder from several different sources is uniform in weight per volume to the extent that 1/4 teaspoon in 65 ml of alcohol or glycol makes a 1% solution as accurately as is needed to make a developer that is of uniform activity from batch to batch.

    I'm not threatened by anything you say. I gain no money from any of my contributions to this forum, and precious little above expenses when I sell an article. I am by nature a teacher who is bound by that nature to spill everything I know. If you want oboe lessons, come see me. I might be able to teach you something about information theory, though I'm a little rusty on that since I retired from NASA.

    I'm having too much fun being able to do exactly what pleases me to feel threatened.
  48. Patrick;

    As I have repeated over and over, use what works for you.

    Don't be surprised if at some time or other, it fails to work.

    Having worked at Cape Canaveral myself for 1.5 years, I saw enough errors by even the best engineers to feel that we can be complacent in the way we do things, or think we know it all.

    See the thread above about a failed hypo mix, for an example. Everything was done right, but the mixture decomposed rapidly evolving H2S and SO2 gasses.

    I have seen several violent explosions at EK as well, when things in the synthetic labs didn't go as expected.

    Chemicals have no regard whatsoever at to the outcome of our mixing them whether it be for our film quality or our safety. I have tried to point out that the prepackaged formulas have undergone a larger series of tests than most other formulas that includes microdensitometry, and RMSG measurements which are not routinely done.

    I see some attempts at doing this in Popular Photography when they test films, but that is a far cry from what should or could be done.

    Therefore, the results of your formulas may be exciting, pleasant to look at and etc, but here is a specific example.

    Using your suggested practices, batch to batch, EI may vary on a 400 film from 300 - 500 and contrast may vary from the ideal 0.6 between 0.5 and 0.7. Sharpness may vary from 10% or 20% below specs up to spec, and grain may vary from 10 - 20% over spec to spec. So, this could be the variation limits of your formulas using impure chemistry and volumetric measures. These variations are very hard to detect unless appropriate tests are run.

    This can be 'printed out' in prints, and the eye might miss a fast film with low contrast or a slow film with high contrast if the differences were subtle enough. Prints might miss this as well if exposure time was adjusted properly.

    Carefully controlled conditions or precise tests would reveal these changes quickly.

    I cannot say what will happen. I can say that these good people on this forum deserve the best possible results by whatever means works best for them.

    The combination of practices you recommend can combine to cause untoward variations in film and paper processing that may cause dissatisfaction. That is an undisputable fact. I have had too many years working in this field to state otherwise. You may say all you wish to the contrary. My experience with chemicals in photographic formulations is probably an order of magnitude greater than yours, and interactions with other photographic engineers doing the same work was similarly great. I am sure they would all agree with me.

    Ron Mowrey
  49. Ron,

    You said: "Using your suggested practices, batch to batch, EI may vary on a 400 film from 300 -
    500 and contrast may vary from the ideal 0.6 between 0.5 and 0.7. Sharpness may vary
    from 10% or 20% below specs up to spec, and grain may vary from 10 - 20% over
    spec to spec. So, this could be the variation limits of your formulas using impure
    chemistry and volumetric measures. These variations are very hard to detect unless
    appropriate tests are run. "

    Could you be more specific? In which of my suggested formulas do you find such discrepancies? Are they measured or theoretical? I have never found such inconsistencies from batch to batch as you describe.
    I did a sensitivity analysis that was published in "Petersen's Photographic", April, 1973 showing possible variations in D-76 due to measurement variations and did not find such variations in results. I did those experiments before I presented teaspoon formulas for a number of developers. You will certainly not find any appreciable effect of 10% errors in sulfite or borax.

    I seldom recommend making up a stock solution using volumetric measurements, although that would probably be the situation least sensitive to errors in measurement. A liter of one of my current stock solutions may do more than 100 standard rolls, the first of which, no matter whose developer you are using, should be a test. You always use volumetric measurements in diluting a stock to working strength, do you not? Should we weigh out our HC110 syrup or stock and the water we use to dilute it? Yet many are diluting HC110 from concentrate where the error in measuring concentrate could easilly be 10%.

    Frankly, I do not understand where our disagreement is. I simply say to one who has no scale or balance, you can mix a formula with certain gross properties and test for specific properties. You will see what I mean by gross properties if you look at "The Darkroom Cookbook". In any one category of working solution you will find rather wide variations of chemicals. In many cases, the chemicals are the same with different amounts. The user has the responsibility of defining the time, temperature, etc. This is true even with premixed commercially available developers.

    I have no complaint against scrupulosity in measurement as long as we know how scrupulous we must be. If you have an argumant, it seems to me that it is to use only analytical grade chemicals. Then you may be justified in specifying and weighing to higher tolerances. Yes, we should know what inert ingredients are present or at least the definition of "inert" used in the MSDS. I have a feeling that somewhere is a general NIOSH definition of "inert" when that term is used in MSDS that would allow us to decide if it means "photographically inert". You could do us a service by finding such a definition if it exists.

    When an MSDS claims 100% purity, I believe the distributor can be held responsible for ingredients that are not included in that 100%.
  50. Patrick;

    First the MSDS issue was resolved by posts by other people explaining to both of us the correct meaning of that information.

    Second, by citing those examples, I merely meant to point out the possible deviation introduced by variations of 2% in the purity of chemicals, not point directly at a specific formula. A 2% halide variation in carbonate could certainly lead to the effects I described and would be very hard to detect visually or through prints.

    Third, without the use of X-ray exposures and RMSG measurements, it would be very difficult to actually quantize the effects we are discussing. If you did these tests, I am not aware of it. Please enlighten me. Our tests on developers included such tests to insure that edge effects and sharpness were within tolerance. Just eyeballing a print or negative is certainly not sufficient. An X-ray exposure will reveal true edge effects and compared with light exposures of knife edge images will give the scientist a feel for the difference between edge effects and light scatter. These are both important in reducing the actual acutance / sharpness to a measureable value.

    I hope this helps. I'm trying to put the evaluation of the image, as well as the preparation of the developer on a more scientific level. Or at least point out how fallible eyeballing can be or how fallible simple picture tests can be.

    Photographic system and process design is a science conducted by trained experts in the field. There are parameters far beyond what the average hobbyist even casually considers Patrick. You have performed a yoeman effort in developing new processing solutions, but there is much that can and should be done to place the work you have done on firmer footing.

    We all deserve that, I think.

    Ron Mowrey
  51. Patrick writes:
    "Yes, we should know what inert ingredients are present or at least the definition of "inert" used in the MSDS. I have a feeling that somewhere is a general NIOSH definition of "inert" when that term is used in MSDS that would allow us to decide if it means "photographically inert". You could do us a service by finding such a definition if it exists.

    "When an MSDS claims 100% purity, I believe the distributor can be held responsible for ingredients that are not included in that 100%."

    OK Patrick, I thought I went over this before - MSDS are for SAFETY - not chemical purity. In case you have not noticed, MSDS stands for Material Safety Data Sheet, not Material Purity Data Sheet. You can not use an MSDS to determine chemical purity or the content of inert materials, especially in a bulk product like soda ash/sodium carbonate. AN MSDS is for your safety, not some application other than that, despite whatever feelings you may have about them.

    You are right, there are regulations that say at what level a component must be listed in an MSDS. For a fuller discussion, you should look at 29CFR (Code of Federal Regulations) 1910.1200. Here's an overview of it:

    Incase you don't have time to look it up, here's part of the section that pertains to your arguement:

    The chemical and common name(s) of all ingredients which have been determined to be health hazards, and which comprise 1% or greater of the composition, except that chemicals identified as carcinogens under paragraph (d) of this section shall be listed if the concentrations are 0.1% or greater; and,

    The chemical and common name(s) of all ingredients which have been determined to be health hazards, and which comprise less than 1% (0.1% for carcinogens) of the mixture, if there is evidence that the ingredient(s) could be released from the mixture in concentrations which would exceed an established OSHA permissible exposure limit or ACGIH Threshold Limit Value, or could present a health risk to employees; and...

    Notice it only pertains to "all ingredients which have been determined to be health hazard" - not to all chemicals, not to inert compounds, not to inpurities, not to anything but all ingredients which have been determined to be health hazard. The only trace compounds you have to list are ones that are going to have health effects, not photographic effects.

    Remember, these are for safety personnel when they come to save your butt when something explodes becasue you ("you" in general, not you specifically, Patrick) were mixing chemcials that were not being used for their intended puroses. They are also for "Right to Know" laws to protect you as an employee or end user of a product. MSDSs are for your safety.

    So materials that are hazardous only have to be listed if they are in concentrations greater than 1.0%. Materials identified as carcinogenic only have to be listed if they comprise more than 0.1%.
    Did you know there are even provisions for "Trade Secrets" in MSDSs? These compounds don't even have to be listed if OSHA determines that it will compromise the trade secrets of a company.

    Remember, these are for safety personnel when they come to save you butt when something explodes becasue you ("you" in general, not you specifically, Patrick) were mixing chemcials that were not being used for their intended puroses. An MSDS is to help the fireman, not to show the amount of inert materials for your photographic application.

    These reasons are why you can't trust an MSDS to have EXACTLY everything that is in a bottle of some product. I'm sure you've seen an MSDS for HC-110. The one I've seen (from around 1994) lists water at 15-20%. Do yo really thing that Kodak's quality control on the amount of water in HC-110 is really a 5% window. I don't think so. They have it listed like that to add some subterfuge so that you cannot just go out and reproduce their product by looking at an MSDS. And there is no telling what compounds are in it less than 1% that they don't have to tell you about. An MSDS is for safety, not industrial espionage.

    And on something like soda ash (your pool pH plus for example), they only have to list what was added to the product. If they used 100% soda ash to fill the bottle, then that's what they write on the MSDS. But if that soda ash has 1% sodium choride as an impurity, then they may not have to list it, as it was not added by them in making up the contents of the bottle - it is an impurity from the mining process. AN MSDS is for safety, not chemcial analysis.

    Patrick, you are just way off base in your use of MSDSs as a for of anything but the most coarse form of analysis.

    Sorry about being so heavy-handed in this post, but this is an important point.

  52. Kirk,

    Heavy handed is only a problem when you must lift it up again.

    I did find the NIOSH regulations and the definition of inert. It may be quite true that the MSDS is for health, but as you also said, when 2% are specified as inert, that means something to health, whether it means anything to photography or not. There is a list of those ingredients that may be considered inert in an MSDS. It does nor include salt or bromides. The fact that 2% of the ingredients of pHPlus from hTh are specified as inert by MSDS is necessarilly significant by NIOSH regulations.

    Another point I have been trying to make is that if you do not know the purity of the stuff you are measuring, don't bother to measure it, either by weight or by volume. Please don't quote obscure "possibilities" applied to formulas I do not present.

    Furthermore, the speculations about what an error of 2% in measuring weight of sodium carbonate are off the wall. When a chemical is that important, it should be determined by titrarion or other analytical means than weight. 2% weight gain in small amounts of sodium carbonate can occur while you are weighing. You will not be able to prove to yourself, let alone to me, that a 2% gain in weight is accompanied by a 2% gain in volume when the weight gain is in water of crystallization.

    The web site to see is:
  53. Patrick;

    Kirk made an excellent point and it sounds as if you miss his point completely. I understand what he is saying and it is of great significance to this whole discussion if you would only listen to what he has said and sit back and consider it.

    He is validating the potential problem that I have pointed out. Neither of us are saying it is a problem or that it will be a problem, but rather that the potential exists for it to be a problem at some time or another. The statistics are against you doing it your way without having someone at some time have a problem using your recommendations.

    The MSDS purity is no guarantee to us for either our developers or our safety. Believe Kirk, he is right.

    And, Kirk, thanks. You state it more clearly than I because you have much more first hand experience in MSDS information than I do. I just have the photo experience end of it. I appreciate the clarity of your comments here.

    Ron Mowrey
  54. "I did find the NIOSH regulations and the definition of inert."

    Well, what did you find? Could you share it?

    "It may be quite true that the MSDS is for health, but as you also said, when 2% are specified as inert, that means something to health, whether it means anything to photography or not."

    Not "may be quite true" but IS quite true. I did not say that 2% were specified as inert, but you are right, that means something - to health, not photography. I believe Ron supposed that the soda ash you are using for sodium carbonate would probably assay out to about 98%. And he is quite possibly right about that.

    But this brings up another important issue. Inert for you, or me, or and MSDS may not all be the same list of inert compounds. It all depends on what is your intended application. Inert for MSDS and inert for photography are probably not the same thing.

    "There is a list of those ingredients that may be considered inert in an MSDS. It does nor include salt or bromides."

    Could you give a link to that list?

    "The fact that 2% of the ingredients of pHPlus from hTh are specified as inert by MSDS is necessarilly significant by NIOSH regulations."

    Yes, significant for health and fire safety.

    "Another point I have been trying to make is that if you do not know the purity of the stuff you are measuring, don't bother to measure it, either by weight or by volume."

    You don't really mean that last sentence - so we can just dump some arbitrary amount of the desired reagents into a container and add an arbitrary amound of water to it? I don't think you are going to get very satisfactory results that way for most of the developers you are making. And even if you are happy with the performance of solutions made up this way, many others will not as they may expect more repeatable results.

    "Please don't quote obscure "possibilities" applied to formulas I do not present."

    I will not and I don't believe I have. But it is those obscure possibilities (or less than obscure possibilities that we don't plan for) that may cause us real issues.

    "Furthermore, the speculations about what an error of 2% in measuring weight of sodium carbonate are off the wall. When a chemical is that important, it should be determined by titrarion or other analytical means than weight. 2% weight gain in small amounts of sodium carbonate can occur while you are weighing. You will not be able to prove to yourself, let alone to me, that a 2% gain in weight is accompanied by a 2% gain in volume when the weight gain is in water of crystallization."

    I'm with you on this - if want to used kitchen measuring devices when doing kitchen chemistry experiments, that's fine with me. And it seems perfectly suited as well.

    But you know - it really depends on the chemical. There are some compounds that are deemed "primary standards" that wieghing is actually the most precise and prefered method of measuring. Of course you have to have the standard in a known condition (i.e. dried at a certain temperature).

    I just believe that if one wants to have a higher level of certainty and repeatablility one would use more precise tools and supplies of know purity.

    If you were paying money for pre-mixed photo chemicals, wouldn't you want them to be using precise methods of measurement when preparing solutions? Would you feel good about buying a bottle of HC-110 that was made in someone's kitchen with teaspoons and measuring cups? I guess what we have found out here is that perhaps that would be fine with you. I'm just looking for something with a little better quality.

    "The web site to see is:"
    When I cut and pasted this link into my browser, it goes to a page of advertisements, and says "page can not be found" at the bottom...

  55. Patrick, Ron -

    Perhaps we should be thankful that the photographic process (at least B&W) when practiced by amateurs, is a very forgiving process. You can be off on exposure, development, mixing of chemicals, time in chemcials... numerous other things, and still get what can be considered acceptable results.

  56. "These compounds don't even have to be listed if OSHA determines that it will compromise the trade secrets of a company."


    Strictly speaking, OSHA doesn't determine trade secrets or whether they will be compromised. The manufacturer presents its arguments for withholding certain information from the MSDS and OSHA either agrees or disagrees.

    It seems like an insignificant point only until you're inside the complex relationships between government research (NIOSH) and regulatory (OSHA, MSHA, EPA) agencies and private industry. Then every nitpicking detail is scrutinized.

    For example, when I was a safety and health inspector for federal OSHA, we referred to hazards as "apparent violations" of an OSHA regulation. If I used the word "apparent" or "appeared", etc., in any other context in my report my supervisor would send it back for a rewrite. So I wasn't even permitted to write "There appeared to be a scaffolding without safety rails, but the employer denied it was in use", or "Apparently an unguarded table saw was no longer in use".

    I make this mundane point because it "appears" that Ron, Patrick and Kirk have become stuck on the merry-go-round of technicalities at the risk of falling off into tautologies.

    In other words, it "appears" that everyone has made his point more than thoroughly and the discussion is now at the stage where each participant is expecting or even demanding that other participants acknowledge where their statements have been either erroneous, imprecise or simply did not differentiate between technicalities in terminology.

    So, let's please wrap it up unless there is something substantially different to offer that will contribute to this thread. I'd like to add this thread to the list of essential reading, linked via the "About" option on the home page for this forum, but I'd rather not have to go in and prune out the superfluous, redundant or simply argumentative.

    And please don't misunderstand me: I appreciate everyone who contributes in a positive manner to the body of factual information on these forums. It's a necessary complement to the more frequent speculations, casual observations and artistic flights of fancy (of which I am often guilty).
  57. Lex;

    Thanks for the reality check. I agree with you.

    Ron Mowrey
  58. Well, after the contributions about sodium carbonate made by
    Patrick and Ron et al. I am beginning to understand why my
    martinis have been off this summer. I think i am going to go
    back to mixing them with sodium sulfite and just doubling the
    amount of ice and olives. I know, I know, this is defeatist and will
    cost me more in the long run, but simplicity has its virtues.

    This is truly the very best thread!

  59. Jerry;

    Shaken or stirred.

    You know that ice behaves differently depending....



    Ron Mowrey
  60. I will make one last point on this thread and no more, for which I'm sure you all are grateful. I do not apply slapdash methods when I am testing a formula for presentation. If a formula is forgiving enough to make use of teaspoon measurements, I see no reason not to say so. In all my writings thus far, at least for processes that are not carried to completion, I have specidied both weights and volumetric measures so that those who do not have a scale or balance may try the process. There are times when I say something like "Throw in a teaspoon of this and a tablespoon of that" but those processes are not done by time and temperature, but are judged complete when a cetain effect is observed.

    I do not rely on anecdotal results, nor do I recommend that anyone else do so. That is why I questioned the sensitivity analysis given by Ron a while back. A proper sensitivity analysis of any of our commonly used developers will show quite a bit of leeway in accuracy of measurements. In most you will not see a significant difference between anhydrous sodium carbonate and the monohydrate when you use equal weights.

    I am not in favor of inaccuracy. I am in favor of knowing what you need and finding how to get it economically. Any time you find a formula where quantities are specified volumetrically, you may certainly weigh those volumes the first time you use it so that you can repeat whatever results you get.
  61. To Patrick and others;

    Please read this thread.

    It is Dannys experience with a published formula in Anchell.

    I'm sorry to have added another post here Patrick, but I was just made aware of this.

    Ron Mowrey
  62. Okay, this thread has been added to the list of interesting threads accessible by clicking on the "About" button on the forum's home page.

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