Everclear has always been great for cleaning burn/arc marks off ceramic.
Prior to initial operation of the klystrons, I processed an order through supply for a case of Everclear. When our supply clerk went to the local liquor store to purchase it, he was warned that a special permit was required for any quantity over a gallon. This was obtained with some delay.
Over the next few years, we used many gallons for cleaning the ceramic on the klystrons, off deck and on deck switch tubes as well as the feed horn windows.
Most of the actual cleaning was performed by the repair center technicians. The Everclear was kept under lock and key and controlled by my secretary. When she asked "Does it really take a fifth of Everclear each time they clean a tube", red flags went up. An inspection of a repairman's thermos bottle solved that problem.
From Wikipedia (for the uninitiated):
Everclear is a brand of neutral grain spirit that is available at concentrations of 75.5% alcohol (151 proof) and 95% alcohol (190 proof), in contrast to hard liquors such as rum and vodka, which typically contain 40%-60% alcohol (80-120 proof). Everclear is commonly added to a variety of other drinks, such as soft drinks, energy drinks, fruit juice, and iced tea. It is used in some cocktails and sometimes in place of vodka or rum in Jello shots. Everclear is also used in cooking because it extracts flavors exceptionally well. It can be used to make homemade liqueurs, such as limoncello.