How to Restore and Polish Brass,
Copper and Bronze - an in-depth discussion:
Lets get the "do nots" out into the open:
- Do not scour your brass with wire or steel wool, nylon or plastic dish cleaners or other severe abrasives, brass and copper are relatively soft and while bronze is much harder, there is no need for it. Not the way to treat an antique.
- Do not use polishes or cleaners that contain ammonia or anhydrous products. It was recently discovered these chemicals cause etching, cracking, fissures and premature aging of soft alloys especially brass, bronze and copper. Many accepted and established named products use these as antioxidants. Read the label or smell it. Just because the manufacturer says it is a polish for brass doesn't mean it won't damage it in the long term.
One of the major signs that there is a problem is when a polish states that it is not recommended for use on aluminum or any other pure metal. A polish should be usable on any metal other than plated surfaces or precious metals. Many of the most established products in the world are now banned from use in Federally funded establishments.
Anhydrous solvents will readily dissolve Zinc, a component of Brass, which is also used in many other metals to reduce oxidization.
Plus anhydrous and ammonia based polishes deteriorate so fast the finish will be dull again in weeks. That is how many of these manufacturers resell their polishes.
- Don't use a polish that contains a vegetable based wax, such as bees wax or carnauba. All vegetable based waxes are acidic and attack what they are supposed to protect. They are also porous so oxidization happens underneath them.
- Don't use lacquers, clearcoats or glazes to protect your brass unless it is exposed to very severe conditions such as a marine environment. It shouldn't be necessary.
- Don't pass your freshly finished work for everybody to admire without picking it up in a cloth. Sweat will attack the preserving waxes and they will slowly get removed.
- If your workpiece is already bright and has some reasonable degree of mirror just use the museum blend.
OK. Enough of that and on with the job...