![]() The idea is to stop development at a precise time, enabling one to then give the film a short 30 second wash after the stop before adding the bleach. One of the things I did do after some experimentation was to use a weak stop bath after development. I've been doing this for years, it makes C41 so cheap to do this way. Then I re-adjust the pH using a small amount of acetic acid and it's ready to go again.Īfter a while, one loses a bit of solution through natural attrition so I just mix up about 250ml of bleach and I'm off again. I originally mixed up a litre of bleach and after usage I rehalogenate the bleach with a fish tank aerator for about 20 minutes or so. I myself have used a bleach regeneration process from Creative Darkroom & Photo techniques, since it was published in that magazine. In the Kodak C41 processing manual that I have, it's stated near the end of the bleach section, that bleach has an indefinite life. I am working on one right now that should solve these problems. They are often less stable than bleach then fix processes. You can get ammonium sulfite from the Formulary by special order (I think) or from ANTEC ().Īvoid all potassium ions like the plague in both the bleach and fix.įilm blixes have a great tendancy to cause silver retention with associated higher grain and blocked highlights in the print. Keep the sodium ion at a minimum and if you overshoot in pH adjust, going too acid, don't use sodium hydroxide, use ammonium hydroxide to go back up in pH. If you put in too much sodium ion, the bleach slows down to a crawl. There are many ways to do this.Īll bleaching in this is based on a mutual reaction of ammonium ion, bromide ion and ferric EDTA (or PDTA). You can use EDTA acid and neutralize it with ammonia as well rather than use disodium EDTA. For the purists the ratio of the molecular weights of ammonium to sodium are virtually unimportant for these purposes. You can replace the ammonium sulfite with an equal weight of sodium sulfite, but you cannot replace the ammonium bromide with sodium bromide or it will be VERY slow to bleach. If this information is wrong, though, I might give that formula a try, keeping PE's processing procedure caveats in mind. I've not tried it, though, in part because from what I understand, potassium ferricyanide is no longer used in commercial bleaches for environmental reasons, and I don't want to bypass environmental concerns. They've also got a ferricyanide bleach formula (80g potassium ferricyanide and 20g potassium bromide in water to make 1l). If you're interested, here's the site with the home-mixed blix formula I tried, but as I said, I can't really recommend that formula. Still, it might be worth at least trying it if you can't put anything else together. The latter works much better than the home-mixed blix and is much less expensive than the Kodak chemicals, but given what I've been hearing about blixes, it might not work as well as separate bleach and fix. So far I've tried one mix-it-yourself blix, which produced overly grainy negatives, and the Paterson Photocolor blix. (Could that have been a typo, PE?)įWIW, I've also recently begun doing my own color processing. Alternatively, does anybody have a more reasonably priced US source for ammonium bromide? Also, what about ammonium sulfite? The usual suppliers don't seem to carry that, although some do have ammonium sulfate. ![]() I have the figures for that as well, but it is hard to get and rather counter productive if you want to save money.ĭoes anybody know offhand if JD Photochem ships to the US? I ask because the usual US photochemistry hobby suppliers (Art Craft, Photographer's Formulary, etc.) either don't carry ammonium bromide or charge much more for it than the $10/pound quoted here - on the order of $20-$40 for 100 grams (~$90-$180/pound). PDTA is 1, 3 propylene diamine tetra acetic acid. If you want that faster bleach, then substitute Ferric Ammonium PDTA for the EDTA. This is a slower bleach than the new RA Bleach III, so use it for about 6 minutes at 100 F. If someone tries to pass off to you a Ferricyanide bleach, remember that it is cost effective, but you need a wash and clearing bath after the color developer and before that type of bleach or you will cause a lot of stain, and you need to wash well before you go into the fix.Īmmonium Ferric EDTA solution (50 - 60%) 200 mlĭissolve in 500 ml water and bring to 1 liter. You cannot easily get the Ammonium Ferric PDTA that Kodak is using in the newest bleach. The Ammonium Ferric EDTA is what is going to cost you the most. ![]()
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