I took my 12×20 plate holder to a local woodworker after he got in touch on Facebook saying he might be able to help.
I explained the situation to him and he managed to very carefully pry the 10
0 year old plinth off the face of the plate holder. The light trap inside that was revealed was a source of great interest to the both of us:
Here you can see How it works. There are two incredibly thin pieces of, what I assume is tin, that is folded over with a thin piece of felt glued to the top of it. The fold in the tin is what provides the ‘spring’ for this to bounce back up when the dark slide is removed. Two of these means that one should already be sprung upwards when the darkslide is still being removed from the outer one.
There is also a very very thin lip carved into the wood that the folded edge of this tin slips under.
Here we were thinking about maybe using a piece of leather folded over to replace the light trap with. The tin had all been corroded and lost it’s spring in some places.
Trying to figure out what material to use to replace the tin, and something that’s not going to be affected by the silver nitrate.
It’s quite ingenious design and very simple, but the craftsmanship that has gone into it is deeply impressive, and the woodworker was highly impressed by it and kept commenting on the cleverness of the whole setup.
Anyway so the journey to figure out how to replace this has begun. Leather? Very thin plastic, like from a coke bottle or something? Some kind of thin metal material? Who knows… will be interesting to see what he or we come up with. I’m glad to have found someone local that’s keen to try.