Turpentine (which is also called spirit of turpentine, oil of turpentine, terebenthine, terebenthene, terebinthine and, colloquially, turps) is a fluid obtained by the distillation of resin harvested from living trees, mainly pines. Principally used as a specialized solvent, it is also a source of material for organic syntheses.
Turpentine is composed of terpenes, primarily the monoterpenes alpha- and beta-pinene, with lesser amounts of carene, camphene, dipentene, and terpinolene.
Substitutes include white spirit or other petroleum distillates – although the constituent chemicals are very different.
Etymology
The word turpentine derives (via French and Latin) from the Greek word τερεβινθίνη terebinthine, in turn the feminine form (to conform to the feminine gender of the Greek word, which means "resin") of an adjective (τερεβίνθινος) derived from the Greek noun (τερέβινθος) for the terebinth tree.
Although the word originally referred to the resinous exudate of terebinth trees (e.g. Chios turpentine, Cyprus turpentine, and Persian turpentine), it now refers to that of coniferous trees, namely crude turpentine (e.g. Venice turpentine is the oleoresin of larch), or the volatile oil part thereof, namely oil (spirit) of turpentine; the later usage is much more common today.
Source trees
Important pines for turpentine production include: maritime pine (Pinus pinaster), Aleppo pine (Pinus halepensis), Masson's pine (Pinus massoniana), Sumatran pine (Pinus merkusii), longleaf pine (Pinus palustris), loblolly pine (Pinus taeda), slash pine (Pinus elliottii), and ponderosa pine (Pinus ponderosa).
To tap into the sap producing layers of the tree, harvesters used a series of hacks to remove the pine bark. Once debarked, pine trees secrete crude turpentine (oleoresin) onto the surface of the wound as a protective measure to seal the opening, resist exposure to micro-organisms and insects, and prevent vital sap loss. Harvesters wounded trees in V-shaped streaks down the length of the trunks to channel the crude turpentine into containers. It was then collected and processed into spirits of turpentine. Crude turpentine yield may be increased by as much as 40% by applying paraquat herbicides to the exposed wood.
The V-shaped cuts are called "catfaces" for their resemblance to a cat's whiskers. These marks on a pine tree reveal it was used to collect resin for turpentine production.
Zallen tells in detail how turpentine (and rosin) are produced as naval stores. Pine trees especially in North Carolina were tapped for sap which was doubly distilled to make turpentine and rosin (aka resin)–hence the name tar heel. The trees were scored with a ledge called a “box” to collect the sap. Large numbers of slaves were used to score the trees, collect and process the sap. Zallen describes this as industrial slavery–different from the more common vision of slaves in agriculture. By the 1840s camphine became the dominant lamp fuel in the US.
The pine trees of North Carolina were well suited to camphine production. The business also provided additional need for slaves as production expanded. Backwoods became more productive. Slaves were often leased in winter when agriculture was slower. The value of many was protected by life insurance. Wilmington, NC became a center of the camphine industry. In cities, gaslighting was also available, but used by the upper classes. Camphine was the fuel of the average family.
Zallen reports that after Ft. Sumpter, turpentine producers were cut off from major markets. Emancipation left them without manpower to collect and process turpentine. The camps were flammable. Many were burned in William Tecumseh Sherman’s march from Savannah to Goldsboro, NC.
Converting crude turpentine to oil of turpentine
Crude turpentine collected from the trees may be evaporated by steam distillation in a copper still. Molten rosin remains in the still bottoms after turpentine has been distilled out. Such turpentine is called gum turpentine. The term gum turpentine may also refer to crude turpentine, which may cause some confusion.