lustering

from The Century Dictionary.

• noun The process of making lustrous or glossy.
• noun In metal-working, same as brightening, 1.
• noun A process for giving to woolen cloth a permanent gloss and smooth surface which will not roughen with wear.
• noun A treatment of furs to render them smooth.
• noun A polishing material, as the black polish used for stoves.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act or process of imparting a luster, as to pottery.
• noun The brightening of a metal in the crucible when it becomes pure, as in certain refining processes.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• verb Present participle of luster.