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#11
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Quote:
http://www.wikihow.com/Use-Measuring-Spoons-and-Cups Don`t be afraid to use instruments like these for making photographic developers. (No batteries required). |
#12
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[QUOTE=Ag-Bromide;1148]Just a thought, I saw a simple recipe by Patrick Gainer for a developer which uses just three easily dissolved ingredients which you measure with spoons and dissolve in a litre of water.
L-ascorbic acid = half a level teaspoon full, Metol = one-eigth level teaspoon full and sodium carbonate = one level teaspoon full. No sulphite required, just pour the solution into your developing tank and use the times for undiluted D-76/ID-11. Any dev without a preservative (the sulphite) will oxidize [I]very[I]fast. Ascorbic acid is an incredibly fast oxidiser as it is. One way of slowing down the oxidaion of the ascorbic acid is to dissolve it in glycerin - also helps with storage (HC1-11) but it's quite an involved chemical process. Metol doesn't dissolve very easily either - and almost not at all in pure water. I can't see that you would end up with a cheaper/ better dev than a propriatory one. The older devs were fine for the films of that era, but film technology has moved on, and developers are now more sophisticated to give full rein to their characteristics. Peter |
#13
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Keith,
read the following which has something to say about preservative and oxidation: http://www.digitaltruth.com/techdata...tainingdev.php I have, for the first time, been paying attention to chemical formulas and how they work because I'm about to test 4 pyro developers to see which I prefer. PMK, Pyrocat-HD, 510-Pyro and Prescysol. I don't really care which turns out to be best as they are all doable but 510-pyro would easily the be the simplest to obtain chemicals and use. But pre-packaged is also easy. I suspect PMK will be the grainiest but we'll see. I think the ones that use TEA have the consistency of HC110 and will keep a long time if not used. Pyrocat-HD only lasts 6 months or so. I don't know about Prescysol but PMK lasts eons. I think Sandy King has come up with a version of Pyrocat-HD which uses Propylene glycol which makes it last a lot longer. I suspect Prescysol and Pyrocat-HD are not disimilar except Prescysol probably has some metol in it whereas Pyrocat-HD uses Phenidone. All guess work and really not that important to me as it's how the negs print that really counts.
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