Sanding and polishing brass and copper

Tarnished brass and copper carry a thin oxide layer; underneath, the metal is usually smooth. Light patina comes off with non-woven abrasive without leaving scratches. Only scratches, dents or soldered joints need sandpaper: P240 for removal, then P400.

Brass and copper are soft – the grit digs in deep very quickly. Going coarser than P240 is rarely worth it, and even after P240 it takes four or five steps before the scratches disappear.

From P600, carry on wet: P600, P1000, P1500, P2000. Water cools and stops metal swarf from lodging in the grit and cutting new scratches. Wrap a strip of sandpaper around pipes and curves and pull it back and forth like a shoe-shine cloth – that gives an even finish all the way round.

If you want a brushed look, stop after P400 or with fine non-woven abrasive and sand everything in one direction.

After P2000, metal polish brings up the high gloss, by hand or with a polishing mop at low speed. Bare brass and copper tarnish again within a few weeks – clear lacquer or metal wax keeps the shine. Before lacquering, wipe off polish residue with silicone remover, otherwise it won’t adhere.