Firestain is a layer of oxides that is visible on the surface of objects made of metal alloys containing copper when the object is heated, as by a jeweler heating a ring to apply solder during a repair. On copper-containing alloys of gold or of silver (such as sterling silver), it presents as a red or purple stain. This is because at high temperatures, oxygen mixes with the copper to form cuprous oxide and then cupric oxide, both of which disrupt the bright polished surface of the finished piece. There are various methods used to either prevent or repair firestain.
Firestain is a layer of oxides that is visible on the surface of objects made of metal alloys containing copper when the object is heated, as by a jeweler...
was discovered to impart the following properties to sterling silver: firescale elimination high tarnish resistance precipitation hardening and simple...
used in alloys to reduce tarnishing, as well as casting porosity and firescale. Such elements include germanium, zinc, platinum, silicon, and boron....
pickle (dilute sulphuric acid or organic acids which are used to remove firescale) buffing wheels polishing compounds. chasing repoussé engraving Silversmiths...
process, and heavy metal remediation in an aqueous environment. Dross Firescale Hammer paint Slag Slag (welding) Cunha, Adriano Ferreira da; Mol, Marcos...
with denatured alcohol to reduce surface oxidation and thus formation of firescale on metals during annealing and soldering operations.[citation needed]...
precious metal alloys. In sterling silver alloys, for instance, it reduces firescale, increases tarnish resistance, and improves precipitation hardening. A...
or lengths of chain. The "black" in "blacksmith" refers to the black firescale[citation needed], a layer of oxides that forms on the surface of the metal...
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