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Bistre

Synonyms: Bistre, Bister, Brauner Lack, Russbraun

Bistre is prepared from the tarry soot of certain woods, especially from that of beech-wood, by the following process: The soot is finely ground and sifted, and then the powder is digested with successive portions of hot water until the latter no longer acquires a brown or yellow tint; the residue is then ground with suitable quantities of gum-water and glycerin, and preserved in the moist state. To form cake-bistre the glycerin is omitted, but more gum is employed. Bistre is not used as an oil-colour.

The tarry matter in bistre is its element of weakness. By exposure to strong light this tarry matter oxidizes, and the residual pigment becomes cooler in hue and paler. Professor Ogden Rood, experimenting with a weak water-colour wash of bistre, found that it lost 19 parts of its original intensity of 25 by an exposure of three and a half months to the summer sun. I have not found so considerable a change to occur with the samples of bistre which I have tried; but this pigment varies much in composition, being obtained from the soot of different woods as well as from that of peat. The most fugitive preparations are those made from samples of soot containing the highest proportions of tarry matters.


Last Update: 2011-01-23