[ In 051020 MMDigest, Don Teach wrote, "The greenish residue found
 [ on valves is verdigris."

A problem with this was discovered in 1963, and so I cleaned the brass
valve seats and lacquered them using some of my mother's clear nail
polish.  I inspected the same valves in 2003 and the brass is corrosion
free and looks fine.

Bruce Clark