Obsidian Aqua catechol staining developer

<p>I'd like to introduce a new developer I've been testing for some time, and will continue to test and use. I call it Obsidian Aqua, for its scalpel-sharpness and water base. </p>

 

<p>Obsidian Aqua is very closely related to Hypercat II, but takes advantage of some of the opportunities an aqueous solution provides for economy, without sacrificing keeping prperties. The main reason for using propylene glycol in Hypercat II is to extend its keeping properties, but this comes at some cost. PG is not locally available in many places, and is expensive to ship, adding considerable expense to the developer. In Obsidian Aqua I've tried to maximize keeping properties while minimizing expense, including shipping costs, by utilizing locally available ingredients where possible, including the use of distilled water as the solvent. Like Hypercat II, OA uses catechol as its sole developing agent, but OA is preserved by metabisulfite in the stock solution, instead of ascorbic acid, and retains carbonate as the accelerator. OA can be made up in sodium or potassium metabisulfites and carbonates, depending on availability. </p>

 

<p>To maximize the keeping properties, the stock solution is highly concentrated. This allows for a higher ratio of catechol to metabisulfite, and a lower ratio of metabisulfite to water compared to other catechol staining developers, which simultaneously improves stain formation and keeping properties. A working solution of catechol/carbonate developer with appropriate carbonate content requires practically no preservative. The preservative is primarily required for the stock solution. </p>

 

<p>To make a working solution, the OA stock solution is dissolved into a solution of 6.66% carbonate, and how this is managed will depend on the carbonate used, and the preferences of the photographer. A 66.6% solution of potassium carbonate can be made by dissolving 666g of potassium carbonate to make 1 liter of stock solution, or 6.66g of either carbonate can be dissolved in a liter of water to make a working solution, or any number of other possibilities. The important thing is that the <em>working developer</em> contains 6.66g of carbonate/ liter. </p>

 

<p>Obsidian Aqua</p>

 

<br>Distilled water 700ml</br>

<br>Metabisulfite (sodium or potassium) 20g</br>

<br>Catechol 250g</br>

<br>Distilled water to 1 liter</br></p>

 

<p>Dilute 1:500 with 6.66% carbonate solution (sodium or potassium, depending on which metabisulfite is used in the OA stock solution). 1 liter of Obsidian Aqua makes 500 liters of working solution. </p>

 

<p>Develop TMY-2 12:00 @ 70F with *geometric agitation sequence. </p>

 

<p>Obsidian Aqua produces negatives of unsurpassed sharpness, excellent gradation, very fine grain, and full film speed. OA can be used with rotary processing, but with some loss of film speed. I hope this developer will be more convenient for my friends overseas, who often need to order supplies from outside their own countries. I highly recommend Artcraft Chemicals for catechol. Artcraft offers 250g of catechol, which wouldn't require any weighing of the chemical to make up the stock solution; just mix the entire amount to make 1 liter. The metabisulfite is not critical, and could be measured with measuring spoons if no scale is available. 1 level teaspoon of metabisulfite weighs approximately 6.5g, so 3 tsp/ liter is close enough. </p>

 

<p>Obsidian Aqua stock solution should keep very well. Though I have no stock solution older than 6 months, I expect it to last at least a year in a partially full glass bottle. Time will tell. </p>

 

 

<p>I hope this formula is useful for anyone desiring the sharpest possible negatives with the best overall Image Quality, at the least possible expense, wherever one might live. </p>

 

 

 

<p>* The notion of a geometric agitation sequence was recently suggested to me, and I've been using it with good results. My method is as follows:</p>

 

<p>I use a count up timer, and begin by agitation continuously for 1 minute. Then I reset the timer and agitate for 10 seconds, according to the following progression (in minutes): 2, 4, 8, 16, 32, etc. </p>

 

<p>A geometric agitation sequence seems appropriate for this kind of very dilute developer, and my results bear this out. </p>

 

Jay,

 

I love your work and all.

 

But can you buy a new keyboard with an enter key next time you're out and about?

<p>Sorry, Richard-- it was a quick copy and paste as I was out the door. </p>

Photo.net's text entry boxes have been quirky this week. I've had to turn off the WYSIWYG editor to get anything accomplished this week, which means I have to use a separate HTML editor. After I resolve the problem with mine I'll edit Jay's post to add paragraph breaks. Or, Jay, if you want to repost it here, I can cut and past it to your initial post.

<p>Thanks, Lex!</p>

<p>I'd like to introduce a new developer I've been testing for some time, and will continue to test and use. I call it Obsidian Aqua, for its scalpel-sharpness and water base. </p>

 

<p>Obsidian Aqua is very closely related to Hypercat II, but takes advantage of some of the opportunities an aqueous solution provides for economy, without sacrificing keeping prperties. The main reason for using propylene glycol in Hypercat II is to extend its keeping properties, but this comes at some cost. PG is not locally available in many places, and is expensive to ship, adding considerable expense to the developer. In Obsidian Aqua I've tried to maximize keeping properties while minimizing expense, including shipping costs, by utilizing locally available ingredients where possible, including the use of distilled water as the solvent. Like Hypercat II, OA uses catechol as its sole developing agent, but OA is preserved by metabisulfite in the stock solution, instead of ascorbic acid, and retains carbonate as the accelerator. OA can be made up in sodium or potassium metabisulfites and carbonates, depending on availability. </p>

 

<p>To maximize the keeping properties, the stock solution is highly concentrated. This allows for a higher ratio of catechol to metabisulfite, and a lower ratio of metabisulfite to water compared to other catechol staining developers, which simultaneously improves stain formation and keeping properties. A working solution of catechol/carbonate developer with appropriate carbonate content requires practically no preservative. The preservative is primarily required for the stock solution. </p>

 

<p>To make a working solution, the OA stock solution is dissolved into a solution of 6.66% carbonate, and how this is managed will depend on the carbonate used, and the preferences of the photographer. A 66.6% solution of potassium carbonate can be made by dissolving 666g of potassium carbonate to make 1 liter of stock solution, or 6.66g of either carbonate can be dissolved in a liter of water to make a working solution, or any number of other possibilities. The important thing is that the <em>working developer</em> contains 6.66g of carbonate/ liter. </p>

 

<p>Obsidian Aqua</p>

 

Distilled water 700ml<br>

Metabisulfite (sodium or potassium) 20g<br>

Catechol 250g<br>

Distilled water to 1 liter<p>

 

<p>Dilute 1:500 with 6.66% carbonate solution (sodium or potassium, depending on which metabisulfite is used in the OA stock solution). 1 liter of Obsidian Aqua makes 500 liters of working solution. </p>

 

<p>Develop TMY-2 12:00 @ 70F with *geometric agitation sequence. </p>

 

<p>Obsidian Aqua produces negatives of unsurpassed sharpness, excellent gradation, very fine grain, and full film speed. OA can be used with rotary processing, but with some loss of film speed. I hope this developer will be more convenient for my friends overseas, who often need to order supplies from outside their own countries. I highly recommend Artcraft Chemicals for catechol. Artcraft offers 250g of catechol, which wouldn't require any weighing of the chemical to make up the stock solution; just mix the entire amount to make 1 liter. The metabisulfite is not critical, and could be measured with measuring spoons if no scale is available. 1 level teaspoon of metabisulfite weighs approximately 6.5g, so 3 tsp/ liter is close enough. </p>

 

<p>Obsidian Aqua stock solution should keep very well. Though I have no stock solution older than 6 months, I expect it to last at least a year in a partially full glass bottle. Time will tell. </p>

 

 

<p>I hope this formula is useful for anyone desiring the sharpest possible negatives with the best overall Image Quality, at the least possible expense, wherever one might live. </p>

 

 

 

<p>* The notion of a geometric agitation sequence was recently suggested to me, and I've been using it with good results. My method is as follows:</p>

 

<p>I use a count up timer, and begin by agitation continuously for 1 minute. Then I reset the timer and agitate for 10 seconds, according to the following progression (in minutes): 2, 4, 8, 16, 32, etc. </p>

 

<p>A geometric agitation sequence seems appropriate for this kind of very dilute developer, and my results bear this out. </p>

 

<p>Well, that didn't work, either. Sorry.</p>

Ugh... some recent tweaks to photo.net's interface has disabled my old familiar Firefox browser. I can't access the WYSIWYG text window, and there are so many scripts running (friendly, not malicious) in the background on photo.net I can't figure out which one is buggering my browser.

 

If you're experiencing similar problems, you may need to change browsers or use an offline HTML editor like NoteTab Light.

 

And my DSL service keeps dropping out the past couple of days due to local t-storms. Happened several times while I was trying to submit the reformatted version of Jay's original post. Let me know if the format is still screwed up.

<p>Jay, Fascinating as always. If you could just package it...</p>

<p>Thanks, Michael. My motivation for this developer was to make it more easily and economically available by avoiding shipping ingredients that can be sourced locally. If, however, one wanted a packaged product, Mike Jacobson at Artcraft Chemicals will make up a kit with all the dry powders pre-measured. The most expensively-shipped ingredient in OA is the carbonate. I pay $9 for 5# of potassium carbonate, locally, but it's about twice that from Artcraft + shipping. Even so, OA is quite economical compared to other catechol staining developers. here's a worse-case scenario breakdown:</p>

<p>Obsidian Aqua from bulk chemicals:</p>

<p>Catechol 250g $26</p>

<p>Potassium meatabisulfite 1# (20g needed) $10.90</p>

<p>Potassium carbonate 10# (3.3Kg needed) $40</p>

<p>Total: $76.90 + shipping </p>

<p>Makes 500 liters of working solution @ $0.15/ liter. </p>

<p>Compared to Pyrocat HD, dry: $29.50 + shipping<br>

Makes 50 liters @ $0.59/liter, or about 4X the cost of Obsidian Aqua, even with the extra chemicals you'd get buying OA as described in the breakdown, meaning your next 500 liters would cost even less than $0.15/liter. </p>

<p>In short, I don't think packaging adds much value, but it does add cost, and that's what I mean to avoid with Obsidian Aqua. </p>

<p>hi Jay,<br>

Great work!<br>

do you have any thoughts about a two bath configuration?<br>

from my experience, carbonates aren't alkaline enough to develop as a B bath so i've used sodium hydroxide.<br>

could you talk a little more about the geometric agitation sequence, about the principle behind it? it sounds like most of the agitation at the beginning helps avoid uneven development. your time of 12:00 (12 min i assume) for tmy2 - do that mean you agitate 1:2:4:8 and then finish at the twelfth minute?<br>

thanks for all your efforts.</p>

<p>Hi Gonzalo,</p>

<p>I agree-- a 1% hydroxide solution is a better choice for a 2-bath than a carbonate solution. For the first bath, try 6ml of OA in 300ml of water, and for the second bath try 3g of hydroxide (sodium or potassium) and develop for 3 minutes in each bath, with 5 seconds agitation every 30 seconds. That should give you good negatives for scanning or silver printing.</p>

<p>The geometric agitation sequence was suggested by someone who heard it from someone else, and I'm not sure where it started. The idea is that agitation is most frequent when the developer is most active, and decreases in frequency as the developer exhausts. What I don't know is the rate of developer exhaustion. There's a chance the developer is still active enough towards the end of development that the agitation is not frequent enough, but I haven't seen any defects with development times under 16 minutes. According to the base 2 progression, a development time of 32 minutes wouldn't get any agitation during the last half of development, and this does worry me a little. Something closer to the f/stop sequence might be safer-- 1,2,3,5,8,11,16,22,32,45, etc. , but I suppose it depends on the activity of the developer, the scene being developed, the film, etc. </p>

<p>Typically, when I'm using a dilute developer with development times of 9:00- 12:00, I'll agitate every 3:00, for development times of 15:00-20:00, I'll agitate every 5:00, and for development times of 30:00- 60:00 I'll agitate every 10:00, and this has been very safe for me. Using the base 2 geometric progression for development times under 16:00 isn't much different than agitating every 3:00, and the same goes for development times between 16:00 and 25:00, but a 32:00 development time ends with a 16:00 rest period, and that's significantly longer than the 10:00 rest periods I typically use in that range, but there's more agitation overall. I don't know. I'm experimenting, and so far, I've had no nasty surprises. </p>

<p>So, to finally answer your question, yes, I agitate for the first minute, then for ten seconds at 2,4,and 8 minutes, instead of my typical 3,6 and 9 minute sequence. Not much difference at these short development times. </p>

<p>Thank you for your kind words, and please let me know if I can be of any help.</p>

I had priced out bulk Pyrocat HD before you posted this thread, and it works out to about $38 for 2L stock, buying the

minimum bulk sizes. That's 200 liters working. And the next 2L of stock, is $16. $54 for 400 liters of working Pyrocat HD.

$.14 per liter in bulk, if my math is correct. But Photographer's Formulary has higher than normal shipping.

 

After doing all that I realized I just don't want to deal with the powders, honestly. I prefer the convenience and safety of it

being in liquid already, and I don't mind paying the markup for that.

 

Notes:

 

Pyrocat HD developer 

 

Distilled Water 750 ml

 

Sodium Metabisulfite 10 g (100g 4.95)

 

Pyrocatechin 50 g (100g 15.95)

 

Phenidone* 2 g (10g 5.95)

 

Potassium Bromide 1 g (10g 3.95)

 

Distilled water to make 1000 ml

 

Stock Solution B

 

Distilled Water 700 ml

 

Potassium Carbonate 750 g  (1lb 6.95)

 

Distilled Water to make 1000ml

<p>Richard,</p>

<p>Obsidian Aqua will always be less expensive than Pyrocat HD, because what matters is the cost to get the developer to your door, and OA doesn't include phenidone or KBr, and uses less metabisulfite and carbonate, but the big differences are in shipping, storage, and shelf life. OA is essentially 5X more concentrated than Pyrocat HD, so that's 5X less opportunity for oxidation, and 5X less shelf space for storing the concentrate. OA also uses more metabisulfite per liter of stock solution than Pyrocat HD, for better shelf life, and less metabisulfite per liter of working solution for better staining. As Charlie Sheen would say, that's bi-winning! </p>

<p>I designed OA to be as economical as possible, and as easy to ship, and part of that strategy is to utilize locally available ingredients wherever possible, including the water, which everyone has. By the time you subtract the cost of having the Formulary make up your Pyrocat HD, and ship it, you've added considerable and unnecessary expense that adds very little value, but the worst part is that for your money, you get a developer that doesn't work as well as OA. Making up a liter of Obsidian Aqua takes a few minutes, and since the catechol doesn't need to be weighed out (if you buy 250g from Artcraft Chemicals), exposure to the dry powder is minimal. A liter of Obsidian Aqua makes 500 liters of working solution, which would develop over 1,500 rolls of film, so it doesn't need to be mixed very often. </p>

<p>I think of Obsidain Aqua more like a recipe than a mail order meal; using the recipe as a guide, cooks can use locally available ingredients for their own regional version. And OA is so simple, it's more like pasta than bouillabaisse. <br>

<br /><br>

I think there are lots of photographers for whom Pyrocat HD is good enough, and for whom the expense of shipping a liquid is more convenience than burden, but for those photographers in remote locations who must pay a premium for all their materials, the availability of which is limited, Obsidian Aqua presents an option with great rewards. </p>

<p>Jay,<br>

thanks for your detailed response.<br>

<br>

i can agree with Jay's logic. funnily enough, here in the middle of Turkey, Catechol is available (and affordable). sodium carbonate and sodium hydroxide are found in the local shops. that alone, plus the great qualities of catechol make this imo an elegant developer ( best utilizing the main developing agent in the simplest way possible ).</p>

<p> all the best,</p>

 

<p>Thanks Gonzalo,</p>

<p>I hope this simple formula is convenient, economical, and useful for you!</p>

<p>I keep getting server errors when I try to send this by private message, so I hope it works here, and it might be of interest to others, as well.</p>

<p>Hi Gonzalo,<br>

A 2-bath staining developer that keeps well presents some challenges, but I don't think these are insurmountable.<br>

One problem is that catechol is very sensitive to contamination of any kind, and although no development takes place in the first developer bath, various dyes and chemicals diffuse out of the film and acumulate in the developer bath, if it is re-used. My fix for this problem might be counterintuitive, but bear with me. The idea is to wash out all of the dyes and other chemicals that might contaminate the first developer bath. It's not possible to do this with 100% effectiveness, as even the gelatin will eventually contaminate the first developer, given enough throughput of film, but a 1% solution of sodium sulfite will eliminate most of the potential contaminants. But we don't want sulfite to build up in the first developer bath either, so it's important to wash thoroughly after the sulfite bath. I recommend the Ilford rapid archival wash sequence of 5,10, and 20 inversions with fresh water. I also recommend processing at higher than normal temperatures to encourage swelling of the emulsion for more efficient diffusion. This has a secondary benefit when using a tanning developer, of enhancing sharpness. 26C is safe for modern emulsions, but care should be taken that all processing solutions are at the same or very similar temperatures to avoid reticulation.A 1% solution of sodium sulfite can be used to pre-wash several films in a session, but should not be kept even overnight.<br>

<br />Now that we've prepared our film for development as well as possible, we encounter the more traditional problems of preservation of staining developers, but these are well known, and their solutions, too.</p>

<p>As you've surmised, the key to staining and to keeping is in the ratios of presevative to catechol, and preservative to total solution volume; less preservative means more stain, but poorer keeping. Another key to keeping is in concentration-- a more concentrated solution will keep better than a more dilute one.So the best design is one that maximizes the ratio of catechol to metabisulfite while minimizing the ratio of metabisulfite to total solution volume, and that means using a concentrated solution. If we take 1:5 as a minimum ratio of metabisulfite to catechol for staining, and 10g of metabisulfite per liter as the minimum concentration of preservative for keeping, that gives us 50g of catechol per liter as our minumum developer concentration. We can minimize the economic implications by keeping total solution volume to a minimum. For example, if you use primarily or exclusively 35mm, you can make 500ml of solution to allow for carryover of solution and maintain film coverage. If you also or primarily shoot 120, you'll need to make 750ml of solution. How economical this will end up being will depend on how well the solution keeps, and how many films you can process before it expires.Fortunately, catechol has the good manners to turn brown when it oxidizes, so you'll have some warning beforehand.<br>

As you know, the sodium hydroxide solution will not keep, but can be used to process several films in a single session, much like the 1% sodium sulfite pre-wash.<br>

As far as I know, no one has tried using such a concentrated catechol 2-bath developer, so you'll be a pioneer! And like all pioneers, you'll have to experiment with development parameters to obtain optimum results. Agitation is one such parameter. Although no development takes place in the first bath, agitation increases the rate of diffusion, but it also increases the risk of aerial oxidation, so finding the right balance will require some experimentation. To begin, I recommend a few gentle inversions to start, and a few more at each minute mark. Since the solution is so concentrated, and the temperature so high, this should be sufficient, but testing will confirm it. In the second bath, development is almost instantaneous, so I recommend continuous and vigorous agitation for the first 30 seconds, and then a few vigorous inversions at each minute mark.<br>

So to sum up my recommendations:<br>

Pre-wash<br>

Water 750ml<br />Sodium sulfite 10g<br />Water to 1 liter<br>

1st bath:<br>

Distilled water 500ml<br />sodium metabisulfite 7.5g<br />Catechol 37.5g<br />Distilled water to 750ml<br>

Or-<br>

Distilled water 250ml<br />Sodium metabisufite 3.3g<br />catechol 15g<br />Distilled water to 300ml<br>

2nd bath<br>

Cold water 750ml<br />Sodium hydroxide 10g<br />Cold water to 1 liter<br>

Develop 3 minutes in each bath,@ 26C with a rapid archival wash sequence between the pre-wash and first developer bath, and the agitation scheme described above.<br>

If catechol is inexpensive, this might be a workable solution, but you'd have to process a lot of film for this to be as economical as standard develoment. If you decide to give it a try, I hope you'll let me know how it works out for you.<br>

Good luck, and happy experimenting!<br>

Jay</p>

<p>Oops! That second variation of the first bath should be:</p>

<p>Distilled water 300ml<br>

Sodium metabisulfite 5g<br>

Catechol 25g<br>

Distilled water to 500ml</p>

<p>sorry</p>

<p>thanks again Jay for your lengthy response.<br>

i'll report results after some testing.<br>

all the best,</p>

<p> gonzalo</p>