Metal finishing Q&As since 1989

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How to finish brass

I have to polish one side each of 2 sheets of 1/8" x 36" x 8' #260 brass to a high polished "mirror" finish for a contractor (I have not been able to locate any #464 navel brass). This is not our normal line of business. We sell portable electric tools and concrete supplies. There is only one place in town that polishes the sheet brass but they are unable to take on the project at this time. Can you describe the procedure. We have access to a large number of tools.

Cheryl Andrews
- Corpus Christi, Texas
 

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Cheryl:

The steps required very much depend on the initial surface condition of your brass (I mean, scratches, dents, nicks, etc.) and of course of what you or the customer mean by "mirror". We polish molds for the plastics industry and you would be surprised how the criteria changes from commercial plastic parts to automotive glasslike transparent lenses for lights, instrument panels, etc. Start with 40 grit size flap sandcloth wheels if the marks are deep or finer if not. Then crossing at 90 deg. every time, erase marks left over by previous sandclothes with finer grits (80, 120 and so on) until there are no finer flaps available, then by hand with sandpaper(220 down to grit 1200 or 1500), then if you still want it better, car polish will do.

Good luck,

Guillermo Marrufo
Monterrey, NL, Mexico