- Joined
- Jan 17, 2006
- Messages
- 21
- Format
- Med. Format Pan
srs5694 said:FWIW, the conventional wisdom is that Efke films are softer than most others and can benefit more from a hardener than can most others. In fact, Freestyle puts this recommendation in their descriptions for at least some of the Efke films they sell (I haven't checked them all). Overall, it seems there are few potential downsides to using a hardener in the stop bath or fixer with Efke films, and at least the potential for some benefit, so you might as well use the hardener. If you don't want to use a hardener with other films, either buy two products or buy a product that lets you add the hardener separately and add it only when required.
Tom Hoskinson said:Once you've damaged the emulsion, it's too late for a hardener to help...
The only really effective hardeners that I'm aware of that are for use prior to development are either formaldehyde based or are based on other aldehydes. As a consequence, there are safety and other issues associated with their use. There is a lot of documentation on this subject (by PE, Suzuki and others).
Photo Engineer said:Tom;
Alum pre hardeners will work just fine.
PE
Tom Hoskinson said:PE, I've not seen a published Alum based prehardener recipe (but I'd love to have one).
phfitz said:Hi there,
Hpoefully it's a pre-hardener
Kodak Hardener F-1a
Water 125°F.............425cc
Sodium Sulfite............60.0g
Acetic Acid 28%.......190.0cc
Potassium Alum..........60.0g
Water to make .............1.0L
Chrome alum contains chromium (III) and not the very toxic chromium (VI) and is therefore safe to use. In fact, chromium (III) is a required trace mineral, I take it every day to help with sugar metabolism.Photo Engineer said:Anyhow, there are several alum hardeners including those using aluminum and chrome. The chrome ones are rather nasty, and they both require a good wash after use and before the developer, but they do work.
Tom Hoskinson said:The only really effective hardeners that I'm aware of that are for use prior to development are either formaldehyde based or are based on other aldehydes. As a consequence, there are safety and other issues associated with their use. There is a lot of documentation on this subject (by PE, Suzuki and others).
Gerald Koch said:Chrome alum contains chromium (III) and not the very toxic chromium (VI) and is therefore safe to use. In fact, chromium (III) is a required trace mineral, I take it every day to help with sugar metabolism.
Photo Engineer said:Gerald, the chrome alum hardener is neutral whereas the aluminum prehardener is acidic.
Both must be washed out completely before development. The hardening is partly reversed in the developer in the case of aluminum, so you have to be careful.
I have used the formalin prehardener below for years with good results. Again, I don't suggest any aldehydes, but this works well and yields good hardness.
formalin 37%, 3 ml
Sodium Sulfate 50 - 100 g
Sodium Carbonate 25 - 50 g
Water to 1 L, pH to 10 with sodium hydroxide
Use for 1 min at 68 deg, then wash thoroughly. There should be little fog with papers, but if there is add 1 g/l of sodium bromide or other antifoggant.
PE
A 5% solution of chrome alum has a pH of 3.2 whereas it takes a 10% solution of alum to match this pH. So chrome alum is actually more acidic in its reaction than common alum.Photo Engineer said:the chrome alum hardener is neutral whereas the aluminum prehardener is acidic.
Tom Hoskinson said:PE, I've sucessfully mixed and used Kodak Prehardener SH-5 in the past to preharden E4 Ektachrome (1980-81) for high temperature processing in E6 chemistry. Your Formalin based hardener formula looks similar to SH-5.
The Kodak SH-5 formula does incorporate benzotriazole for film fog suppression.
For most of my Efke film processing, I will continue to follow this rule: IF IT AINT BROKE DON'T FIX IT!
Thus, No pre or post hardener when I am developing Efke films with tanning developers.
I may try using pre hardener on some occasions (if I encounter problems with emulsion damage - and so far - I have not) when I am developing Efke films with non-staining and tanning developers.
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