Pig Bristles, the hairs of a pig or wild boar, which are widely used to make brushes, paintbrushes etc. A distinction is made between ridge bristles from the backbone, which are most valued, and side bristles. The long, strong, elastic bristles are only found in northern and eastern countries, in Russia, Poland and Romania; Northern Germany, Hungary, China and the East Indies supply middleware; winter crop is better than summer crop, and bristles from wild boar are preferred to those from domestic pigs. The raw bristles are combed to separate the wool which is used as upholstery material, sorted, cleaned with potassium alum water or soap, and bleached in the sun or with sulfuric acid, sometimes dyed black by boiling with lead sugar.
Source: Meyers Großes Konversations-Lexikon, 6. Auflage 1905–1909