Tuesday, 4 December 2007
Black Paints
Carbon, in one form or another, is the base of all black pigments. By far the most common of these, as used in structural plants, is graphite. Other black pigments are lamp-black (including carbon black) and bone-black, the former being produced in many grades, varying in price from twopence to half a crown per pound. Bone-black, which is refuse from the sugar-house black, varies in the percentage of carbon contained, which is usually about 10 or 12 per cent, the remainder being the mineral matter originally present in the bone, and containing 3 or 4 per cent of carbonate, whilst most of the remainder is phosphate of lime. Lamp-black is an absolutely impalpable powder, which having a small amount of greasy matter in it, greatly retards the drying of the oil with which it may be mixed. For this reason it is not used by itself, but is added in small quantity to other paints, which it affects by changing their colour, and probably their durability. For example, it is a common practice to add it to red lead, in order to tone down its brilliant colour, and also to correct the tendency it has to turn white, due to the conversion of the red oxide of lead into the carbonate.Labels: Black Paints
posted by kanx1976 at
14:34
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