Re testing dry tintype
This week I made a batch of the AJ 12 emulsion and tried dry tintypes again,here is what I found out.
The emulsion,when used for tintype, is only suitable for dry and cool conditions. When I used it up to the spring of this year it began showing signs of limitations. Humidity deafenatly has an efect on this emulsion when subjected to the Ammoniumtyocyanate in the developer.
The area of preperation is in my basment where the humidity reaches over 60% in the summer where as now it is 30-35%.
In high humidity the emulsion will dsolve in the developer containig the cyanate, hardener has little effect.
So,the main thing is,this emulsion is good for dry tintypes in the winter,I think I will make up some 8X10 plates and go out and do some winter shooting.
If you use any thiocyanate on gelatin coatings, you must use very good hardening, otherwise the gelatin will dissolve. Sorry to hear about your problems. Maybe use of a good formalin hardening bath or perhardener might help.
The emulsion coating is very thin so that makes it susseptible to dammage. I am going to try a diferent emulsion and see what that will do.
I have made this one thicker but it seemed to show fog in the shadow areas,so it's thinness is good for the shadows.
A well known commercial brand of emulsion that is used for dry tins is thicker and uses silver bromide and chloride,will try chloride in place of iodide.