Recently I found some very old unexposed glass plates. Kranz Ultra Ortho 18/10 DIN 9x12cm. Probably 90-100 years old.
I intend to use these plates in my grandfathers camera.
Has anybody experience in developing these plates? Is there any chance in succes?
Check to make sure DIN speed still means the same today. I think it does but double check.
Add about 5 stops exposure and tray develop under red safelight in HC-110 dil B at a cold temperature like 60F. Watch for image / fog to form and pull before the fog gets too bad. Stop and fix (about 5 minutes in rapid fixer)
DIN 18/10º is today 50 ASA, but 40 according to that table. I wonder which one changed? But the difference is just 1/3 of a stop, and you'll need to give those old plates a bit more exposure anyway.