The problem with most substitutes is that they do not contain a chelating agent for iron and copper and are thus subject to sudden failure. The following formula contains two chelating agents triethanolamine and salicylic acid.
DS-10
Distilled water (50°C) 750 ml
Sodium sulfite (anhy) 75.0 g
Triethanolamine¡ 10.0 ml
Ascorbic acid 8.0 g
Dimezone S 0.15 g
Salicylic acid 1.0 g
Boric acid 4.0 g
Distilled water to make 1.0 l
What evidence indicates that triethanolamine is a chelator? It has never acted as such, particularly against iron, in any formula I have ever developed.
The triethanolamine chelates for copper, the salicylic acid for iron. This formula and 3 others were developed by Ryuji Suzuki who spent many months researching the Fenton reaction. The two ions mentioned cause very rapid decomposition of ascorbate ion. Iron is a common contaminant of several chemicals used in photography. Therefore, the use of distilled water has little effect in preventing the problem. Both the triethanolamine and the salicylic acid are also part of the buffering system of the developer and cannot be omitted without further changes. While some ascorbate developers are simple variants of D-76 merely making direct substitution for the hydroquine, the above formula uses the correct ratio for the two developing agents.
BTW, the fact that these two chemicals chelate for certain for certain ions can be seen from the appropriate stability constants. You can also gauge the relative effectiveness of several chelators by looking at the stability constants. Kodak uses DTPA in Xtol but that is hard to obtain for the average person.
The preservative Sodium Omadine turns a purple color in the presence of iron. Formulations with 10% or more TEA turn purple with even a trace amount of iron contamination. 0.2% EDTA prevents this color change from occurring. I wonder why TEA shows no chelating power in my experience.
Gerald, your knowledge and experiance is always welcome. Unfortunately many raw chemicals (not only DTPA) are increasingly difficult or impossible to get, e.g. Triethanolamine, Dimezone S or Boric acid, or ridiculously expensive in useful quantities. I've seen the recipe you posted above before, but many of us - including me - can't make it ourselves. So we have to buy the ready made product - Xtol in this case - or use simpler recipes. That's why I posted the link to the instant Mytol. I also use low grade chemicals, e.g. "bubble ex" sodium sulfite and had no problems with the developer in use since 12 months. The double strenght stock dilution I made even had a light yellow color at last but still worked fine. I guess storing the developer in small glass bottles helps a lot to keep it working.
OK, I know it doesn't exist, but I wish there were a liquid equivalent to XTOL that had a long shelf life and could be mixed as needed for one shot development, preferably a product that would come from a single-solution bottle.
If you are ready for a bit of self mixing, Mark Overton has extensively reported about his (there was a url link here which no longer exists) which is similar in composition to Xtol and produces comparable results. A 200 g/l solution of Sodium Sulfite in water is also quite stable if you keep it in an air tight bottle, so you can mix Xtol like developer working solution from two liquid concentrates.
If you're not up for making Mocon, DD-X is kind of similar and is a liquid. I would expect Xtol to outlive it though, especially since you can store it basically forever as powder.
Why does DD-X cost so much more than XTOL? Are they really that similar?
It is a good question and has been asked several times on APUG but I have yet to see a good answer. Even if you compare it on a like for like basis. 5L of Xtol in the U.K. is about half the price of 5L of DDX on a 1+4 working solution basis.
I presume that even in the U.S. there is quite a difference in price, given that it is usually a U.S. APUGer that raises the price of DDX issue.
What's the difference in China? Thanks
pentaxuser
It is a good question and has been asked several times on APUG but I have yet to see a good answer. Even if you compare it on a like for like basis. 5L of Xtol in the U.K. is about half the price of 5L of DDX on a 1+4 working solution basis.
I presume that even in the U.S. there is quite a difference in price, given that it is usually a U.S. APUGer that raises the price of DDX issue.
What's the difference in China? Thanks
pentaxuser
DD-X is sold as a liquid, and Xtol is a powder. Powder developers are almost always cheaper than liquids because of the high cost of the plastic bottles liquids are packaged in, and the cost of shipping bulky, heavy bottles of liquids from manufacturer to distributor to stores.
In that case, why is Ilford Rapid Fixer so cheap then? It's in the same container as DD-X, is a liquid, and costs no where near as much as the Ilford developer. I think I paid $15 for my bottle of Rapid Fixer. I'm not sure as I havent bought one in many months.
In that case, why is Ilford Rapid Fixer so cheap then? It's in the same container as DD-X, is a liquid, and costs no where near as much as the Ilford developer. I think I paid $15 for my bottle of Rapid Fixer. I'm not sure as I havent bought one in many months.
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