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rknewcomb
11-Apr-2008, 06:46
Hello,
I'm using Efke 25 film in 4x5 and 8x10 size and trying to process it without getting scratches. Many have said that it has a soft emulsion and a hardening fixer is needed. I could use regular kodak fixer or the Kodak Rapid fix that has hardener but I have two issues with that.
1) I would prefer to mix my own fixer from sodium thiosulfate because it is cheap to make and also because my darkroom sessions are sometimes spaced far enough in time that a freshly made fixer seems like a good idea vs whats been sitting in the bottle since the last time.
2) The odor of Kodak fixer is fairly strong for my darkroom that is located in my house.
So, can I just add some Kodak hardening solution to my homebrew fixer? I have some from the past when I've used the rapid fixer without the hardener plus there are hardeners that can be mixed from scratch.
Is there a less smelly hardening fix that I can mix in smaller batches?
thanks for the help.
Robert newcomb

Jim Noel
11-Apr-2008, 10:07
I use any one of several pyro developers. Because of their tanning ability, and with careful handling I don't have scratching problems. Theyrequire a non-hardening fixer. I use the Ryuji formula.

Doremus Scudder
12-Apr-2008, 10:04
Here is the recipe for Kodak F-6 odorless hardening fix. I used to use this a lot with good results

Kodak Fixing Bath F-6
Odorless Bath for Films, Plates, and Papers
Water, about 50 Celsius (125° F.) 600 ml
Sodium Thiosulfate (Hypo) 240 g
Sodium Sulfite, desiccated 15 g
* Acetic Acid, 28% 48 ml
Kodalk 15 g
Potassium Alum 15 g
Cold water to make 1 liter

* To make approximately 28% acetic acid from glacial acetic acid, dilute three parts of glacial acetic acid with eight parts of water.
Dissolve chemicals in order given. To prevent sulfurization, mix the potassium alum separately in a small amount of hot water then add this last with rapid stirring.
This bath should be used in conjunction with a stop bath such as Kodak Stop Bath SB-1 or Kodak Stop Bath SB-1a, or an acid hardening bath such as Kodak Hardening Bath SB-3 to obtain the full useful hardening life. The hardening life (capacity) is equal to that of Kodak Fixing Bath F-5 provided an acid stop bath is used. With a water rinse the life is about one-half that of Kodak Fixing Bath F-5.
The hardener may also be mixed separately as a stock solution as detailed in Kodak Hardener F-6a.

Kodak Hardener F-6a
Stock Solution For Preparing Kodak Fixing Bath F-6
Water, about 50 Celsius (125° F.) 600 ml
Sodium Sulfite, desiccated 75.0 g
* Acetic Acid, 28% 235.0 ml
Kodalk 75.0 g
Potassium Alum 75.0 g
Cold water to make 1.0 liter

* To make approximately 28% acetic acid from glacial acetic acid, dilute three parts of glacial acetic acid with eight parts of water.
Dissolve chemicals in order given.
Add one part of the cool stock hardener solution slowly to 4 parts of cool 30% hypo solution (2.5 pounds per gallon of solution), while stirring the hypo rapidly


Hope this helps,

Doremus Scudder

G Benaim
14-Nov-2008, 07:19
Any idea if this type of hardener can be added to or used in conjunction w rapid fixer? I'm about to order some potassium alum for this purpose. Thanks.