Most decorative architectural metal is an alloy, not a pure element. Brass is copper and zinc; bronze is copper and tin; stainless steel is iron with chromium (and often nickel) added for corrosion resistance. The base alloy sets the metal's colour and hardness before any finishing happens.
Finishing is a separate manufacturing step — polishing, brushing, plating, or chemically ageing the surface — and it changes both appearance and how the metal behaves day to day far more than the base alloy alone.
Polished, brushed, and matte finishes
Polished finishes are mechanically buffed to a mirror shine and show fingerprints and water spots most readily. Brushed or satin finishes have fine, directional scratches that diffuse light and hide daily marks better — a common reason brushed stainless dominates busy kitchens.
Matte or bead-blasted finishes scatter light further still, at the cost of a slightly more industrial look. None of these change the underlying metal's corrosion resistance — that is set by the alloy, not the surface texture.
Living finishes and patina
Unlacquered brass, copper, and bronze are “living finishes” — they oxidise and darken with air, moisture, and handling. Manufacturers sometimes apply an artificial patina to shortcut this process, then seal it with wax or lacquer to slow further change.
Choosing a living finish means accepting that a bathroom faucet will look different in year three than on day one — for some homeowners that patina is the entire appeal; for others it reads as tarnish that needs polishing. Confirm which you are getting before ordering unlacquered fixtures.