Julie,

The best way to deal with metals is to consult a qualified conservation
expert. I used to contact the National Park Service in Tucson, Arizona for
advice and then sought bids. For metals recovered from the ruins of the 1796
Spanish Fort Guijarros and mid 19th century whaling station, I contracted
with a conservator in Santa Barbara, California (company name was Wharton &
Associates, but has added another name). They all said the first step was to
immerse the metal in distilled water, watch for discoloration, and repeat the
baths over several weeks until all the salts are removed. Salt crystals can
cause metal to break down. Once salts are removed, the conservators can
decide which treatments are appropriate for removing corrosion and
stabilizing the corrosion process. They also provide a report on what they
did and what to do for monitoring over a period of time. I have known
archaeologists to experiment with methods of cleaning metals, but the best
thing you can do for your keys and other artifacts is work with a
professional conservator.

Ron May
Legacy 106, Inc.