I know that is intended to be a p
ss take, but cleaning of shellac discs is the subject of great interest for archival storage of historical recordings. See the following for the process of taking an old and mouldy shellac disc and restoring it:
https://www.nedcc.org/audio-preservation/cleaning-discs
Even broken or damaged discs and cylinders are recoverable using optical imaging techniques
https://www.nedcc.org/audio-preservation/irene
Craig