As the other gentlemen said, Scrubbing Bubbles. I got a jug of the pump spray, opened it and poured the contents into a container that will just fit an average DE. I drop the whole thing in and leave it for five minutes.

Rinse and scrub with a soft toothbrush. For gold plate Windex won't take it off and will clean it. For either silver of gold a dip in mineral oil overnight is optional. On TTO (twist to open) or adjustables it sometimes helps the action.