I have a decorative piece of copper with a rough surface which, due to it's fabrication process, has some embedded aluminum particles in the copper surface.

I cannot remove the aluminum from the copper surface by grinding or polishing because it would damage the decorative nature of the piece.

After giving it some thought I remembered that an aqueous solution of copper sulfate and salt (non-iodized) is a very effective way to etch aluminum.

My theory is that if I submerge this piece of copper which contains embedded aluminum particles into an aqueous solution of copper sulfate and salt that the decorative copper surface will be unaffected, but the aluminum will react to form aluminum sulfate and loose copper particles thus permanently removing the aluminum from the copper surface.

Am I overlooking any potentially dangerous reactions by simultaneously combining copper, copper sulfate, aluminum, and salt, or does this sound like a safe and viable solution?

Your idea should work fine.

My first thought would have been to remove the aluminium by dissolving it in sodium hydroxide solution.

Either option may damage any patination.

Also, in either case, wash the piece thoroughly after treatment before letting it dry.

Edited September 20, 20196 yr by John Cuthber

The coppersulfate solution will probably react with the aluminium and cover it with copper (immersion plating). Better is to use a dilutet solution of an acid . Copper is resistant to dilute acids, like hydrochloric, sulfuric or acetic acid. Aluminium will be dissolved.

Edited September 20, 20196 yr by chenbeier

In the presence of air, those acids attack copper.

To some extent the copper sulphate and common salt also does.

Sodium hydroxide will dissolve aluminum, but not copper. It is, however, more corrosive to skin.