Enamel

Tooth enamel is the hardest substance in your body.

Tooth enamel is mostly composed of hydroxyapatite.

A small daub of very watery enamel should be taken on the end of the spatula and laid upon the metal where it is to be enameled.

Silver foils are used on copper and gold work in order to obtain better enamel effects, for most transparent colors are shown to best advantage over silver.

Jewels there were also, brooches of gold and silver and gilded bronze, set with gems and bright with enamel, and arm rings and torques of gold.

There's a crack in the pot's enamel.

Their plumed helmes are wrought with beaten golde, Their ſwords enameld, and about their neckes Hangs maſſie chaines of golde downe to the waſte, In euery part exceding braue and rich.

Oft he [the serpent] bowed / His turret crest and sleek enamelled neck.

to enamel card paper; to enamel leather or cloth