Cleaning up an old plate

[JamesBon92007]

If you are using a bleach that contains sodium hypochlorite I suggest rinsing it in a bath of sodium thiosulphate 2% (photographic hypo) to neutralize any residual chlorine and then rinse very thoroughly.

 

[Byrdie]

I'll second the use of denture cleaner. May need to soak for several weeks depending on the condition of the plate.