HP21 - What's the best way to clean it?

[Kees Bouw]

Hi,

I would be extremely careful with using alcohol on the keyboard even if there are no labels printed on it. The alcohol can damage the clear matte finish and cause a shiny surface. I have learned this the hard way when I used alcohol to clean the keyboard of a HP-67, just on the black areas, and I removed the matte finish. I have tried several types of paint to restore it but without success.

Kees.