Electropolishing Aluminum


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Q. What can you tell me about aluminum electropolishing? –M.N.

A. Electropolishing is typically associated with the finishing of stainless steel, however, aluminum can be electropolished as well. Electropolishing of aluminum is an excellent substitute for bright dipping, which produces chemical byproducts that are toxic. A basic primer on the process is available at pfonline.com/articles/electropolishing-as-a-pretreatment-for-anodizing

Electropolishing bath chemistry is based on a mixture of acids, but a process using sodium carbonate/trisodium phosphate is also used. A commercial formulation is:

Component Concentration
Sufuric acid 70% by volume
Phosphoric acid 15% by volume
Nitric acid 1% by volume
Water 14% by volume
Operating conditions Range
Temperature 165-185°F
Time 2-15 min
Voltage 10
ASF 30-50








More information is available in the ASM Metals Handbook, Volume 5, available from ASM International at asminternational.org. This book is expensive, but an excellent addition to your plating library.