For hardening my emulsions I have only ever used ChromeAlum and Chromium Acetate. The ChromeAlum needs to be used at a weight of 0.5% of the weight of the dissolved gelatin and the Chromium Acetate needs to be used at half that amount.
I would now like to experiment with Glyoxal ,Gluteraldehyde and Mucobromic Acid. Does anyone know what amounts are best to use for those?
I use all hardeners at the same concentration and weight/unit of gelatin. Nothing really critical about them unless you want to control the aldehyde effect on keeping. Aldehydes tend to cause after hardening and also fog emulsions.
I suggest mucochloric acid over mucoobromic. I also suggest it be used mixed with formalin for best results.
Actually, I don't suggest Glutaraldehyde due to the extreme toxicity of the fumes. I have read that there are outstanding lawsuits on this over the use of a glutaraldehyde hardening solution for some processes due to toxic reactions by some.