C-41 Fixer recipe
I'm mixing a C-41 Fixer from scratch using the following recipe:
Water 110-120F 800 ml
Ammonium thiosulfate 60% 162 ml
Sod. Sulfite anhyd. 24 g
EDTA Sodium salt 1.25 g
Sod. Bisulfite anhyd. 12.4 g
Water to make 1 litre
I'm substituting Sodium Thiosulphite for the Ammonium (I understand this will be a slower fix time but have no choice)
So 2 questions:
1. Does anyone know what quantity of Sodium Thiosulphite I should use for this recipe?
2. How long should my fix time be?
Do a test
Take some of the same film that you are using. What you want is a sample of exposed leader. Of course, being C-41, it should be any color neg, but the universe is perverse.
Plop it in a bit of the fixer in question, and time the, um, time until clear. Double or triple that to be safe.
You may find these old posts of mine pertinent. Or, not.
C41 fixers should have a controlled pH and should be very strong fixers. If you change from Ammonium Thiosulfate to Sodium Sulfate, you likely change pH and will have to readjust. And Sodium Thiosulfate is weaker than Ammonium Thiosulfate, so you might end up with retained silver.
If you insist on using Sodium Thiosulfate, start with Agfa 304 or Ole's OF-1 recipe and adjust pH to 6.5 with Sodium Carbonate and Sodium Bisulfite. Consider two bath fixing if you detect retained silver.
Originally Posted by Paul Verizzo
So I tried your suggestion with a bit of colour neg. When you say "until clear" do you mean until all the emulsion has stripped off or until it becomes opaque?
Emulsion stripped off? Is that battery acid fixer you are using? :)
Originally Posted by HumbleP
I just took some hypo+ammonium sulfate fixer I mixed a LONG time ago. A snip of color film didn't change significantly in an hour of bath. I then tried some B&W, and although I was busy and not watching the clock, it certainly cleared up in less than 15 minutes. Coulda been three. Or a tiny fraction thereof.
If you are bent on using hypo, I guess you will have to do your own testing. If you looked at the material in the links I provided, you should be able to narrow things down somewhat. Since it's hard to overfix, consider time to be the price of sticking with hypo.