- Not Shellac? Alack! -
To the Editor:
You mentioned Diamond Discs recently (“A Diamond Disc as Big as the Ritz,” August 2017) and wrote that they have an outer coating of shellac. It is not. The coating is Edison’s version of Bakelite. Edison called it “Condensite.”
Ron L’Herault
North Attleboro, Massachusetts
Thank you for the clarification. I always wondered why people recommended cleaning them with rubbing alcohol, since alcohol is injurious to shellac. Perhaps that they are not shellac explains why.
It’s amazing that I’ve had a Diamond Disc player since 1973 and never knew about Edison’s proprietary plastic compound. I'd just assumed the material was shellac.
One thing I also discovered was that after about 1921 Edison changed the composition of the core material from wood flour to a more moisture-resistant china clay. They did immersion tests that demonstrated the new material would stand 15-20 minutes under water. This is possibly why I’ve never had a problem cleaning records with soap and water (using the paintbrush and vacuum cleaner method), though I would never actually immerse any records in water.
The earlier Diamond Discs are more troublesome, and I’ve found pre-1921 records that had been poorly stored with major warping, cracking, and lamination-separation issues. The big problem with the 1920s Diamond Discs is that the labels are
