Turpentine is a general term used for the volatile oils present in trees, primarily coniferous. Alpha- and beta-terpene are often found in the highest concentrations, while other compounds at lesser but still significant concentrations include limonene, camphene, myrcene, and terpineol, among others.

Crude sulphate turpentine (CST) is a term used for turpentine recovered during the kraft pulping of wood. CST includes the terpenes, but it will also contain other substances released from the wood, as well as undesired by-products of the pulping process, such as alcohols and the odorous total reduced sulphur (TRS) compounds. The total fraction of non-terpene compounds found in CST can vary greatly, but for design purposes 30% is often used. Red oil is CST recovered from foul condensate steam stripping systems. Red oils will contain higher levels of the odorous TRS compounds. CST will typically contain about 0.5 to 1% TRS, whereas the concentration in the red oils will be in the range of 5 to 10%. It is this higher level of contamination which give the Red oils their distinctive coloring.

CST is toxic and extremely flammable so caution must be used when handling it. CST recovered from the kraft pulping process is typically used as a fuel or sold as a by-product. CST dumped to sewer in large quantities can upset the effluent treatment system (it is toxic to the bugs in high concentrations). Whenever possible foul condensates containing high levels of CST should be recovered and treated, preferably in the turpentine recovery system, otherwise in the stripping system where it will eventually make its way to incineration with the stripper off gas (SOG).