The best way to clean the platen is to not allow it to come in contact with dry mount tissue. In other words prevention is the best course of action. However, should cleaning be required then the platen cleaner that others have mentioned is good. Dents if very small can sometimes be corrected by using a drop of distilled water applied with a spotting brush. This will swell the gelatin and allow it to even out. If the emulsion is broken then no corrective action will correct it. Good luck.
Originally Posted by Ka