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POLISHING SOFT, LOW-TEMP ALLOYS?

Does anyone know how to polish soft low-temperature-melting alloys of bismuth, lead and cadmium? Any work with a polishing wheel simply melts the surface and makes it worse! We have also had no luck by hand. We hope to polish this material prior to plating with nickel. The nickel will then be backed and the low-temp alloy melted away . . . hopefully leaving a good finish. Thanks in advance for your help!

William B. Cushman
- Pensacola, Florida
1999

The addition of a one oz tire wt per cup of lead alloy will add enough antimony to make the lead alloy significantly harder and not change the meltion point too much. Also let your casting set for at least 2 days, a week is better. It hardens significantly with time because of the antimony. Slow the speed of your wheel down and you will cut the temperature rise down. Cutting the speed of the wheel down by half will cut your heat down to about 1/4th of what you are getting in a given length of time now. Also, less pressure, less friction equals less heat.Less polishing also.

James Watts
- Navarre, Florida
1999