Enamel, Blue. Prep. 1. White ‘frit’ or ‘flux,’ coloured with oxide of cobalt.
2. Sand, red lead, and nitre, of each 10 parts; flint glass or ground flints, 20 parts; oxide of cobalt, 1 part, more or less; depending on the desired depth of colour.
Enamel, Brown. Prep. 1. Manganese, 5 parts; red lead, 16 parts; flint powder, 8 parts; as before.
2. (Wynn.) Manganese, 9 parts; red lead, 34 parts; flint powder, 16 parts.
3. Red lead and calcined iron, of each, 1 part; antimony, litharge, and sand, of each, 2 parts. To be added in any required proportion to white ‘frit,’ according to the colour desired. A little oxide of cobalt or zaffre is frequently added to alter the shade.
Enamel, Green. Prep. 1. ‘Flux’ or ‘frit,’ 2 lbs.; black oxide of copper, 1 oz.; as before.
2. As the last, but adding red oxide of iron, 1⁄2 dr. Less decisive.
3. Copper dust and litharge, of each 2 oz.; nitre, 1 oz.; sand, 4 oz.; ‘flux’ or ‘frit,’ q. s.
4. From transparent ‘frit,’ any quantity; oxide of chromium, q. s. to colour. Colour superb; it will stand a great heat; in common hands, however, it frequently turns on the dead-leaf tinge.
5. Transparent ‘flux,’ 5 oz.; black oxide of copper, 20 to 40 gr.; oxide of chromium, 2 gr. Resembles the emerald.