jordan_w.

<p>A lot of the liquid concentrates (developers especially) contain high levels of sodium sulfite, other ionic materials, and some organic solvents, all of which will tend to depress the freezing point of the solution. They may not have crystallized at all.</p>

<p>The reversal process has a few extra steps -- specifically a bleach step, a clearing bath, a re-exposure step, and a second development step. Recommend that you Google for more details. You will have to home-mix most of the solutions. Many of the raw materials are available locally in Toronto, but others are not.</p>

<p>Henry's, Vistek, Downtown Camera should all carry D76.</p>

<p>That sounds like a light leak during development, to be honest. Light leaks in the camera tend to show as a distinct pattern on each frame. What kind of tank are you using?</p>

<p>Is the dark region one solid horizontal "dark" stripe across the length of the film, or is there a pattern to it?</p>

<p>I can't comment on the other issues, but I would be very careful substituting a carbonate in for the metaborate. </p>

<p>Retailers seem to be one of the very worst sources of information about product availability.</p>

<p>For Part A, dissolve a little bit of sodium sulfite (1-2 grams) first, then the metol, then the rest of the sodium sulfite. Having your water pre-heated to 30-35C will help (but let it cool to room temperature before using it).</p>

<p>For Part B, the temperature doesn't really matter, as sodium metaborate is quite soluble.</p>

<p>It's a great developer -- good luck! </p>

<p>pH is a property of solutions, not dry chemical compounds. It's not correct to say that sodium hydroxide has a "higher pH" than sodium carbonate. <br>

Depending on concentration and whatever else you have in your solution, you may or may not be able to replace the hydroxide with the carbonate. It certainly won't be a 1:1 substitution and you will want to use a pH meter.</p>

<p>Bob probably means <em>citric acid</em>-based stop baths, not ascorbic acid. Ascorbic acid is a developer ingredient and would make a poor stop bath.<br>

If you are simply looking for a developer that doesn't have metol or hydroquinone, there are a number that fit the bill (XTOL comes to mind). But there are other toxic and / or irritating substances in developer besides those two. I would take Lex's comments very seriously. </p>

<p>Alan,</p>

<p>AFAIK, there is no requirement to associate products with the patents that describe them. When you see it happen, it's usually a "patent pending" notice (to discourage would-be copy-cats, I suppose) The fact that Kodak holds the patents is sufficient -- they are entitled to protect their intellectual property, whether it has been used in XTOL or not.</p>

<p>Kodak probably has multiple patents that relate to XTOL -- from proprietary chemical ingredients, to methods of "encapsulating" the powders to prevent caking, the packaging material, the formulation itself, etc. Listing them all could get tedious.</p>

<p> </p>

<p><br /> Patent examples for chemical formulations don't always correspond 1:1 to a commercial product, and unless you're able to get the (confidential) XTOL formulation from Kodak, you'll never know which of the examples (if any) in those patents is the actual XTOL recipe. However, it's very likely that the recipe <em>is</em> covered in the range of formulations claimed in the patents.</p>

<p>The patent that Alan Marcus cited was issued in 1998, so it still has many years left.</p>

<p>As John mentions, it's likely that "true" XTOL is not the same as any of the examples in that patent. However, the claims cover a range of compositions, which would probably cover the actual formulation of "true" XTOL. </p>

<p>XTOL contains ascorbic acid, but in its working solution (with all that sodium metaborate and sodium sulfite present) the pH is about 8. The ascorbic acid is present as the ascorbate ion under those conditions. </p>

<p>I'd be really surprised if the ascorbate is able to do anything to get rid of the base colour -- that colour is very hard (or impossible) to remove, as it's present in the film base itself (not just the emulsion)</p>

<p>Dan, can you post a side-by-side comparison (scans or photos of your positives) demonstrating the difference? (preferably with the edge markings showing?)</p>

<p>In using the words "home made" and mentioning coffee / vitamin C / washing-soda developers, I automatically assumed the OP asking about colour developers that one can make with supermarket ingredients, rather than specialty chemical purposes. If this is what he meant, the answer is that they don't exist.</p>

<p>As others have posted, even "best guess" approximations to the Kodak C-41 formula are fraught with problems. And you'll need to find a source of CD-4 if you want to mix it yourself.</p>

<p>Unfortunately, the answer to your question is "no", and if you read up on the chemistry of colour film you'll see why. Colour development requires that one or more specific couplers be present in the developer. These couplers are fairly complex organic compounds and are not used for any other purpose.</p>

<p>The horrible smell is common when developing film in "coffee" developers, from what I recall. I believe it comes from free-basing a lot of volatile amines that are normally present as salts in the instant coffee. </p>

<p>I definitely think it's worthwhile to play with home-brew developers like coffee / vitamin C, but I don't know of any usable home-brew fixers that just use off-the-shelf ingredients. You should probably stick to a commercial fixer. </p>

<p>For what it's worth, a water de-chlorinator could contain any reducing agent -- even ascorbic acid (a quick Google for the ingredients of aquarium water de-chlorinating solution revealed one that actually does use ascorbic acid -- chemically, it's perfect for de-chlorination, but will develop your film rather than fixing it). Even if your de-chlorinator does contain sodium thiosulfate, it is probably too weak. Sodium thiosulfate fixers generally have at least 100 g/L of thiosulfate.</p>

<p>I've even seen people claim that developing film at 24C (75F or so) "doesn't work as well" as developing at 20C. "After all, Kodak's tables all give times for 20C, that's what they design their films for!"</p>

<p>I have compliled a list of techniques that can be used to generate B&W slides. It's been linked to before on this forum, and is also the first hit when you search Google for "B&W slides" :)</p>

<p><a href="http://www.photosensitive.ca/wp/methods-for-producing-bw-slides">http://www.photosensitive.ca/wp/methods-for-producing-bw-slides</a></p>

<p>There have been some interesting cases in the world of organic chemistry that illustrate the pitalls of relying on purity specifications.</p>

<p>In one widely reported case (around 2005 or so) a British research group reported that they had succeeded in carrying out a reaction called the Suzuki coupling in the absence of its usual catalyst (a palladium compound). The catalyst is normally absolutely essential for this reaction. On further examination they found that the research-grade sodium carbonate they were using for the reaction contained unreported ppb levels of Pd, which was enough to cause the reaction to "go". </p>

<p>Another example of this is playing out in the literature right now -- a group in Germany found some interesting chemistry that appears to be catalyzed by CuI, an unusual finding in this case. However, when they used rigorously purified CuI, their yields dropped. It turns out that the original CuI sample contained small amounts of an Fe salt, and that the Fe and Cu were both required for reaction.</p>

<p>I'm sure stuff like this happens in photographic chemistry, too -- perhaps not in B&W development, but maybe in colour, emulsion-making, or some exotic processes. Higher purity may not always better, and in some cases the chemistry just isn't well-characterised enough to draw firm conclusions.</p>

<p>

<blockquote>

<p><em>Can TMAX (PURE B&W NEG FILM) be developed by colour machine processing?</em><br>

Black and white film developer is different from color film developer (c-41 process), so unless you are using a c-41 black and white film (T-Max is not) then no, they would not be able to run it through their machine and get good results. Your film would have to be developed by hand, which is why they ask more to develop it.</p>

 

</blockquote>

<p>It's not just a developer issue. The final two stages of C-41 processing are a bleach step and a fix step, which together remove all silver (exposed and unexposed) from the film. As a result, running regular B&W through C-41 results in blank film. </p>

</p>

<p>Ron, I've hear this "myth" before, too, and I'm not sure where it comes from. It would be interesting to trace it to its origins. My suspicion is that it is tied to the advent of TMAX and other new-technology films -- they presented something of a learning curve and maybe it was just easier to blame the developer when things went wrong.</p>

<p>I think the you-mix-it crowd is both too small and too savvy to be the driving force behind the idea that there are universal incompatibilities between old / new developers and new / old films -- while hobbyist scratch-mixed developers have their issues, I've never seen anyone make blanket statements about their insuitability for any particular type of film.</p>

<p>The Photographer's Formulary sells a Photo-Flo replacement that is meant to be used at a rate of two drops per roll. I have yet to use more than about 20 ml of my 100-ml bottle, bought 7 years ago.</p>

<p>It's a complicated topic, but either The Darkroom Cookbook or The Film Developing Cookbook are usable summaries. Try your local library before buying.</p>