PAINTS, DYES, AND VARNISHES 



There is a difference in the selection of woods from 

 which the charcoal is made, however, the soft woods 

 making much better pigments than the hard. Spent 

 tan-bark makes a good pigment charcoal, and is used 

 extensively for this purpose in some places. 



The usual method of burning the charcoal is to pile 

 short pieces of wood on end into a stack resembling a 

 cock of hay, some of these stacks containing several cords 

 of wood. When completed, the stack is covered with a 

 layer of clay or dirt, a certain number of openings being 

 left for the admission of air. The wood is then lighted, 

 and allowed to char by slow combustion, the rate of 

 burning being regulated by the openings through the 

 dirt covering. If combustion takes place too slowly 

 the openings are made larger; on the other hand, 

 they are reduced in size if sufficient air is being ad- 

 mitted to support a bright blaze. 



To make such charcoal into practical pigment it 

 must be reduced to a fine powder by grinding. It must 

 then be washed thoroughly, either in water or a dilute 

 acid, to remove all impurities. 



A charcoal black, known as "vine black," is made 

 from the lees and the pressed grapes used in the process 

 of wine-making. In some of the wine-producing 

 regions of Europe the industry of making charcoal for 

 this vine black is quite an extensive one, and the pig- 

 ment so produced is of very fine quality. The first 

 step in the process of making this black is that of drying 

 the lees at a moderate temperature. When the moisture 

 has been removed the dried lees are placed in iron tubes 

 (old stove-pipes, frequently) coated with clay, and 



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