I saw the mention of polishing brass.  Recognizing that any brass
before 1948 is classed as "antique," I offer the following details.
I don't remember which conservator gave me this... I've slept since
then.  :-)

Caution:  This technique can cause damage to antique brass and should
be used only when there is a need for high polish appearance.  It is
best to avoid exposing brasses and bronzes to ammonia.

Cleaning procedure:

1. Rinse: ammonia (60%) plus distilled water (40%) for 5 minutes
2. Clear rinse (distilled water)
3. Calgon detergent
4. Clear rinse (distilled water)
5. Polish: sodium bicarbonate
6. Rinse with alcohol or acetone
7. Seal: Krylon #1301
   http://www.krylon.com/products/crystal-clear-acrylic/ 

Wm. Grant Chapman
West Point, New York