Hardening stop bath for Foma Films

Paul Howell

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Harry Champlin in Champlin on Fine Grain 1937 gives a formula for a hardening stop bath,

500 cc Water
7 grams Sodium Bisulphite
7 grams Potassium Chrome Alum

My thinking is while it will not help with any defects in production or while is being wound in the camera, will be useful in fix and wash. I am not familiar with the formula, any thoughts?
 
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Adrian Bacon

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I shoot Foma pretty regularly and use Ilford Rapid fixer and don't really have much issue with scratches and what not. It absolutely is easier to damage than anything from Kodak and Ilford, but I suspect most of the scratches issues reported are just sloppy handling, or a camera that will damage it but not damage a more resistant film. Yes, there can be things that slip through QC at Foma, but they can't possibly do nothing but chronically dump defective film out onto the market and expect to stay in business.
 
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Paul Howell

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I did, thanks I fixed it.
I use T4 which does not have a hardener. I have not had any issues with Foma, but seeing the number of posts thinking that using the hardening stop bath is a small bit of insurance.
 

Alan9940

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I find Foma's emulsions to be on the soft side so I use a hardening fixer. I don't with most of the other films I use.
 

koraks

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Paul Howell said:
I have not had any issues with Foma
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Me neither, so I never bothered with hardening. It wouldn't hurt, but I doubt it would help much for the problems I've seen people post with foma films. I can't recall any issues where I would expect a hardener to have made a difference.
 

mshchem

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Alan9940 said:
I find Foma's emulsions to be on the soft side so I use a hardening fixer. I don't with most of the other films I use.
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I have found this to be the case with Fomatone fb paper. I use a hardening fixer, I'm still a believer in hardening fixer for everything I do. Hardening stop would be OK if it was in the solution long enough.
Back in the old days, tropical development schemes used a strong hardener containing formalin, even before the developer. This was back in the 30s and 40s, no need today.
 

Jeremy Saint-Peyre

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Hello Paul !

I'm home processing R100 as reversal, the permanganate bleach cause the emulsion to soften a lot in the second developer. So i'm going to give a try to your hardening bath recipe.

I'd like to know how long you use it ? Longer then the regular minute for a stop bath ? Did you try a longer time ?

Thank you !

Jeremy
 
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Paul Howell

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I have not gotten around to making it up, need to order additional chemistry, and you have very good question, had not thought about how many rolls or sheets per liter. Champlin does not discuss how many likely too expensive to dump after one use. I could test the PH after mixing and test after use to see when the stop bath changes PH to the point it is not longer viable?
 

Jeremy Saint-Peyre

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I ordered some chemistry, i'll order some film next week to test it. I'm more interested in the hardening ability than the stop, but if the Ph is directly linked to the hardening capacity... I can have Sodium Bisulfate at 0,006€/gr and Potassium Alun at 0,008€/gr. I need 4L of chemistery to process my 16mm x 30,5m film, so it would cost... 0,79€ of chemistry
 

Maris

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koraks said:
Me neither, so I never bothered with hardening. It wouldn't hurt, but I doubt it would help much for the problems I've seen people post with foma films. I can't recall any issues where I would expect a hardener to have made a difference.
Click to expand...
Me too. I've used a lot of Foma 8x10 and 4x5 sheet film plus 120 roll film over the years. After exposure the emulsion side of my Foma films only touch air or liquid until the the films have finished drying and then they go into archival negative sleeves. Maybe I'm missing something? What is it that people do when processing film that hardener is required to defend against?
 

Jeremy Saint-Peyre

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Hi Maris,

Well, for myself, i'm processing in reversal with a Potassium Permanganate/Sulfuric Acid Bleach that soften the emulsion, not to the point it disolve, but still... so i'll try with hardening stop this morning !
 

Rick A

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I've been using Pyro developers (PMK and Pyrocat-HD) with both Foma and Efke films, no need for a hardening fixer. I think being cautious with stop bath is a greater concern, using it at half strength or water rinses instead helps eliminate the dreaded pin holes in the emulsion.
 
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