from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A deep blue paint and ceramic pigment produced by pulverizing a glass made of silica, potash, and cobalt oxide.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. a deep blue pigment made from powdered glass mixed with cobalt oxide
from the GNU version of the Collaborative International Dictionary of English
- n. A deep blue pigment or coloring material used in various arts. It is a vitreous substance made of cobalt, potash, and calcined quartz fused, and reduced to a powder.
from The Century Dictionary and Cyclopedia
- n. Common glass tinged of a fine deep blue by the protoxid of cobalt.
The "variegated" colored soaps are produced by adding the various colors, such as smalt and vermilion, previously mixed with water, to the soap in a melted state; these colors are but slightly crutched in, hence the streaky appearance or party color of the soap; this kind is also termed "marbled" soap.
"smalt" blue forget-me-not with large flowers were abundant, also an oxalis very like our own wood-sorrel.
Ground zaffer was also the basis of the painters 'material smalt.
Less-fine smalt was acceptable for coarse painting or industrial purposes.
For eighteenth-century painters, the mineral origins suggested that smalt would be an especially stable color.
Here, quality of the coloring material was determined by the degree of fineness to which the smalt was ground.
For about two centuries before that determination, cobalt was prepared in Europe, converted to zaffer to make blue-colored glass and blue enamel, and from zaffer to smalt for painting.
This was true in general, but smalt was known to discolor in oil media unless used with small amounts of white lead and, like any coloring material, if poorly made or inexpertly used, it lost color over time.
From left to right at top, there are seven colors, all pure reference (i.e., unmixed), ranging from Spanish white through deeper blue colors — smalt and indigo — to atramentum siricum, a dark blue-black.
Colors grouped under smalt include hyacinth, sea green, leek color, ingrain purple, paonaceus, and iron gray.