I think this is a moisture issue. I’ll get good looking iodine coverage, but after exposure I’m getting streaks that are obviously from buffing. There is no image on the streaks either. I think I need to re evaluate my plating process, and make sure the plates are 100% dry before the final buff. Anyone else have this happen?
Are you still using that unlined wooden iodine fuming box shown on your website?
Iodine crystals will absorb moisture unless kept in an airtight container.
I’d advise lining that box with a small glass food container and your box lid with a sheet of glass or Teflon. If you can’t find a new liner box that fits, try garage sales.
Glass food containers were more popular before Tupper ware became available.
Doh! And to think I knew that already. Yeah I bet that is the issue. Man am I ever glad I found this list. Getting too close to the problem makes you overlook the simple things. I’ll stop at Fred’s Thrifty Acres (heh that’ll root out any Michiganders) and get glass. Thanks!
A more obvious solution to moisture on the buffed plate is heating the back of the plate with a hair dryer just before you put it in the iodine box.
To remove moisture from the iodine in the box Daguerreotypists used to place a small dish of freshly calcined (melted) Calcium chloride in the box each morning before starting operations. The CaCl2 will absorb the water but not iodine and liquefy. You can drive off the water by reheating this desiccant and use it again. Absorbing the iodine or bromine on silica gel will also keep your box dry but it isn’t as easy to regenerate when it becomes saturated with water.