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Lamp-Black

Synonyms: Lamp-Black, Noir De Lampe, Noir De Fumée, Noir De Houille, Russ, Lampenschwarz

When resins, resinous woods, fatty oils and fats, paraffin and paraffin oil, or coal-tar oils, are burnt with an insufficient supply of air, a considerable part of the carbon they contain may be deposited in the form of soot. This soot is not, however, pure carbon, but retains variable proportions of the tarry products of imperfect combustion or destructive distillation; these impart to lamp-black a more or less pronounced warm brownish hue, except in the cases in which it has been prepared by processes specially devised to intercept the tarry and oily products in question. Sometimes small furnaces, sometimes large lamps with long wicks are employed in its manufacture, the soot given off being collected in two or more receivers; the soot first deposited contains the larger part of the impurities. This point may be illustrated by the simple experiment of depressing a white porcelain plate into the flame of a candle; the nearer the plate to the wick, the browner will be the soot deposited.

Lamp-black carefully made is an unalterable pigment; but its employment for pictorial purposes has frequently been objected to by writers on artistic practice as tending to heaviness and opacity in the shadows. With the exception of a few pigments of organic origin, which in water-colour painting have a tendency to cede some of their colouring matter to any kind of carbonaceous black, lamp-black exerts no injurious influence upon any pigments which are stable when used alone.

Numerous carbonaceous substances have been used as black or brown-black pigments. Amongst these anthracite and common bituminous coal may be named. Van Man-der and De Mayerne both mention forge or pit coal. Black shales and black slates have long been employed in the preparation of dark grey pigments. These minerals owe their colour in part to carbon or compounds of carbon, in part to very finely divided iron pyrites. They are permanent, so far as the carbon present is concerned.


Last Update: 2011-01-23