RA-4: Prepare All 10L of Blix?
In August, I bought the Kodak Ektacolor RA developer and blix concentrates from B&H:
This is enough to make ten liters of each chemical -- a big initial investment for a first-timer, but it seemed to be the most cost effective and fuss free way to get into RA-4.
For the developer,I plan to prepare the ten liters of working solution at once and keep in twenty 500ml PET water bottles filled to the top. I'll probably use about one bottle per session, and I can keep the bottles in the dark -- in room temperature or the fridge.
It's the blix that I'm unsure about. Is it as sensitive to oxidation as the developer? Also I've read that the bleach and fix don't play well together over long periods, and that it might be best to prepare smaller amounts (two liters) as needed.
Any thoughts on this? If I prepare smaller amounts as needed, how best to keep the concentrates once they've been opened?
The ammonium thiosulfate part - I think it is the B- not the red ferricycanide part, can sulfate out as a sulfur precipitate over time just like ordinary b&w fixer concentrate.
So I mix up my RA-RT blix 1l or 2L at a time. I have had the thio sulfur out, and resorted to mixing the replacement from bulk thio I had around, along with a few other mix from scratch ingredients, while I waited forthe replacenent order to come in.
Prior to RA-RT I used to mix from scratch the whole of RA-4 process chemistry.
Once I got a roller procesor I needed something that was more resistant to aerial oxidation, which RT most ddefinitly is.
my real name, imagine that.
Mike is correct in that the sulfur precipitates over time but I have to put my two cents in and state that that sulfur never made a difference to me. For both B&W and color, I have simply filtered out the particles and nothing seemed to matter for the worse. Whenever you have liquid chemistry the opportunity always exists to mix partial quantities. Just be accurate with your measurements and it is best to use metric, even if the kit is quantified in avoirdupois. I had some RA4 blix concentrate (the black part, ferris-something) for a dozen years and after that time it kind of clumped to the bottom in one black mass. After much shaking it worked fine when mixed with the equally old ammonium thiosulfate part. I use potassium ferricyanide for that component now because I find it both easier and less messy. But, remember, that the mixture does not last more than about 30 minutes when mixed with the fix. - David Lyga
I just mix up what I need.
Part A 40ml
Part B 18ml
Part C 40ml
Water to make 1000ml
Part A 140ml
Part B 200ml
Water to make 1000ml.
Since all of the unused chemstry stays as the concentrates the shelf life will be as long as possible.
It has been observed by many on this forum, including myself, that mixed RA-4 developer, properly stored, (glass or good quality plastic containers, completely filled) can last longer than bottles of concentrates. It may not be true with bleach-fix.
Originally Posted by pinholer
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Thanks for the information. I was not aware of that.
Originally Posted by RPC
I'd say mix it all. Even in one huge container, the last batch I used lasted for well over a year, mixed.
My suggestion (not necessarily the Bible here) is to simply keep the blix concentrates separate and mix what you need. My answer would be, perhaps, different with developers. - David Lyga
Revisiting this... I think I'll mix two liters working solution at a time from the concentrate. So initially, I'll prepare two liters working solution of blix, and then decant the parts A and B of the concentrate into smaller bottles that I can squeeze the air out of. Unless someone has a better idea...
(By the way, the Part B is dark purple/black. Is that right?)
Yes, Part B is dark purple / black