Emulsional problems with dry tintypes
I have recently been experiencing a new wrinkle with the dry tintypes.
The last couple of batches of emulsion had a horrendous case of self destruction during development, I think due to the area of plate coating and drying (basement) has become damp as it does this time of year.
The sympom is this, the surface of the emulsion becomes soft and furry looking and begins to shread apart and dissolving in the developer containing thyocyanate. I am susspecting the gelatin has not cured compleatly due to humidity. This was not a problem during the winter when the air is very dry.
Using a dehumidifyer does not help. I tested some of the same plates by placing them in a plain Dektol developer with no problems. I then placed a glass plate coated with a heaver gelatin laden emulsion in the developer with thyocyanate and found no problems. The next thing is to add more gelatin to the already made emulsion to see if this will check the problem.
Presoaking in Alum solution had little effect.
I think I may have a cure to the problem.
First I added 30% more gelatin to the ready made batch of emulsion.
Next I set the exposed plate in a .5gm Alum : oz. water solution for one minute, developed in usual dektol 1:1 with cyanate.
Other option was to use developer D-19 undiluted with cyanate, no hardening required but the development time shuld be increased by 50%.