Pine tar is a form of wood tar produced by the high temperature carbonization of pine wood in anoxic conditions (dry distillation or destructive distillation). The wood is rapidly decomposed by applying heat and pressure in a closed container; the primary resulting products are charcoal and pine tar. Pine tar consists primarily of aromatic hydrocarbons, tar acids, and tar bases. Components of tar vary according to the pyrolytic process (e.g. method, duration, temperature) and origin of the wood (e.g. age of pine trees, type of soil, and moisture conditions during tree growth). The choice of wood, design of kiln, burning, and collection of the tar can vary. Only pine stumps and roots are used in the traditional production of pine tar. Pine tar has a long history as a wood preservative, as a wood sealant for maritime use, in roofing construction and maintenance, in soaps, and in the treatment of carbuncles and skin diseases, such as psoriasis, eczema, and rosacea. It is used in baseball to enhance the grip of a hitter's bat; it is also sometimes used by pitchers to improve their grip on the ball, in violation of the rules. Pine tar has long been used in Scandinavian nations as a preservative for wood which may be exposed to harsh conditions, including outdoor furniture and ship decking and rigging. The high-grade pine tar used in this application is often called Stockholm Tar since, for many years, a single company held a royal monopoly on its export out of Stockholm, Sweden. It is also known as "Archangel Tar". Tar and pitch for maritime use was in such demand that it became an important export for the American colonies, which had extensive pine forests. North Carolinians became known as "Tar Heels." Pine tar was used as a preservative on the bottoms of traditional Nordic-style skis until modern synthetic materials replaced wood in their construction. It also helped waxes adhere, which aided such skis’ grip and glide. Pine tar is widely used as a veterinary care product, particularly as an antiseptic and hoof care treatment for horses and cattle.