Anneal
Anneal ({not transcribed}) , transitive verb
[Old English anelen to heat, burn, Anglo-Saxon analan; an on + alan to burn; also Old English anelen to enamel, prob. influenced by Old French neeler, nieler, to put a black enamel on gold or silver, French nieller, from Late Latin nigellare to blacken, from Latin nigellus blackish, dim. of niger black. Compare Niello, Negro.]
1.
To subject to great heat, and then cool slowly, as glass, cast iron, steel, or other metal, for the purpose of rendering it less brittle; to temper; to toughen.
2.
To heat, as glass, tiles, or earthenware, in order to fix the colors laid on them.