Turpentine is made by collecting the sticky resin that pine trees produce naturally, then separating its volatile components from the heavier solids through distillation. That basic process has been used for centuries and still accounts for a large share of world production, but a second major route now rivals it: recovering turpentine as a byproduct of the wood-pulp industry. Both paths start with the same raw material, pine wood or pine resin, and both rely on heat to drive off the lighter, aromatic fraction we call turpentine while leaving behind rosin or other residues.
Why Pine Trees Produce Resin in the First Place
Pine resin is not a waste product or sap in the way most people think of tree fluids. It is an active defense system. When bark beetles bore into a conifer, or when a branch snaps in a storm, the tree responds by flooding the wound with oleoresin, a thick, sticky mixture of lighter compounds called monoterpenes and heavier compounds called diterpenes. The lighter fraction, which will eventually become turpentine, acts as a solvent that is toxic to invading insects and fungi. The heavier fraction hardens into a seal over the wound, physically blocking further entry. This combination of chemical warfare and wound-sealing is one of the reasons conifers have survived for hundreds of millions of years.1PubMed. DEFENSIVE RESIN BIOSYNTHESIS IN CONIFERS
The practical upshot for turpentine production is that pine trees are essentially pre-loaded with the raw material. Wound a pine in the right way, and it will push resin toward the surface on its own. The entire gum turpentine industry is built on exploiting this defensive reflex.
Tapping Live Trees
The oldest and most direct method is tapping, which works much like tapping a maple tree for syrup but targets resin instead of watery sap. A worker strips a patch of bark and cuts a shallow groove or wound into the sapwood. The tree responds by secreting resin, which flows down the groove and collects in a cup or container attached below. Every week or two, a fresh cut is made just above the previous one to keep the resin flowing. In many traditional systems, the groove is angled downward in a V-shape so gravity guides the resin toward the collection point.2Scientific Reports. Efficient resin production using stimulant pastes in Pinus elliottii × P. caribaea families
Different regions have developed their own variations. The traditional Spanish method, for instance, uses a long, narrow wound that is refreshed over the tapping season, while the circular groove method cuts a ring-like channel around part of the trunk. Research comparing these approaches in maritime pine found that the traditional method yielded about 1.4 times more resin than the circular groove under the same conditions.3European Journal of Forest Research. Resin yield response to different tapping methods and stimulant pastes in Pinus pinaster Ait
Chemical Stimulants
One of the biggest developments in modern resin tapping is the use of chemical stimulant pastes applied to the fresh wound. These pastes contain compounds that trick the tree into producing more resin than it otherwise would. Ethephon, a synthetic plant hormone that releases ethylene gas inside the tissue, is one of the most widely used. Sulfuric acid is another common ingredient, serving as a base irritant that keeps the wound open longer and prevents the resin ducts from sealing shut. The pastes are typically thickened with something like rice husk powder so they cling to the wound surface rather than dripping off.2Scientific Reports. Efficient resin production using stimulant pastes in Pinus elliottii × P. caribaea families
The yield gains can be dramatic. In trials on maritime pine, stimulant pastes increased resin output by up to six times compared to unstimulated wounds.3European Journal of Forest Research. Resin yield response to different tapping methods and stimulant pastes in Pinus pinaster Ait A study on Masson pine found that combining ethephon stimulation with a film mulch covering over the wound boosted resin yield even further while also improving the quality of the resin and rosin collected.4Biomass and Bioenergy. Resin tapping in Masson pine (Pinus massoniana): Response of resin yield and its product quality to film mulching and chemical stimulation treatments On its own, ethephon increased the quantity of resin but did not notably improve its composition. The film mulch, which reduces evaporation and contamination of the wound, appears to be the ingredient that helps on the quality side.
Steam Distillation of Crude Resin
Once the crude resin, often called gum or oleoresin, is collected from the trees, it needs to be processed. The resin at this stage is a thick, sticky mass that contains volatile terpenes (the future turpentine), non-volatile diterpene acids (the future rosin), and various impurities like bark fragments, insects, and dirt. The first step is usually straining or filtering the gum to remove the large debris.
The filtered gum is then loaded into a still and heated with steam. The volatile terpenes have lower boiling points than the resin acids, so steam carries them off as vapor while the heavier rosin stays behind in the still as a molten liquid. The terpene-laden steam passes through a condenser, where it cools and returns to liquid form. This liquid is crude gum turpentine. The rosin left in the still is drained off separately and allowed to cool into the hard, brittle, amber-colored solid familiar to violinists and baseball players.
The ratio of turpentine to rosin varies with species and growing conditions, but a rough rule of thumb is that crude oleoresin yields somewhere around 15 to 25 percent turpentine by weight, with the bulk of the remainder being rosin. This gum turpentine, produced by tapping and steam distillation, is generally considered the highest quality because it starts from a relatively clean, fresh source.
Crude Sulfate Turpentine from Paper Mills
The second major source of turpentine is the kraft pulping process used to make paper and cardboard. In a kraft mill, wood chips are cooked in a hot alkaline solution to dissolve the lignin that binds wood fibers together. Pine wood chips still contain plenty of resin, and the heat and chemicals in the digester release the volatile terpenes from that resin. These gases are collected from the top of the digester and condensed. The resulting liquid is called crude sulfate turpentine, or CST.
CST is chemically similar to gum turpentine in its terpene content, but it comes with a significant drawback: sulfur contamination. The kraft process uses sodium sulfide as a key cooking chemical, and some of that sulfur ends up bound to the terpene molecules or present as dissolved sulfur compounds like dimethyl sulfide and dimethyl disulfide. These give crude sulfate turpentine a notoriously foul smell and limit its direct use without further treatment.
Cleaning Up Sulfate Turpentine
Removing sulfur from CST is a major industrial challenge. A pilot-scale study on kraft-mill turpentine started with a sulfur content of about 1,260 parts per million and used a sequence of hypochlorite oxidation, air oxidation, water washing, and distillation to bring it down progressively. After all steps, the sulfur content dropped to roughly 29 ppm.5BioResources. Refining of crude sulfate turpentine obtained from a kraft pulp mill: A pilot scale treatment That is a major reduction, but for some applications even lower levels are needed.
More aggressive desulfurization techniques can push the number even further. One approach combines oxidation with peracetic acid and adsorption onto activated carbon. Under optimized conditions, this combination method achieved sulfur levels below 5 ppm, essentially bringing the product to purity levels comparable to gum turpentine.6Environmental Technology & Innovation. Ultra-deep desulfurization of crude sulfated turpentine using oxidation, adsorption and novel combination approach The trade-off is that these intensive purification steps add cost and complexity, which is why CST has historically been considered a lower-grade product compared to gum turpentine, even though its core terpene composition is similar.
What Is Actually Inside Turpentine
Turpentine is not a single chemical compound. It is a mixture of monoterpenes, with the exact proportions depending heavily on the pine species it came from. The dominant component in most commercial turpentine is alpha-pinene, a bicyclic terpene with a sharp, woody smell. Beta-pinene, 3-carene, and limonene are other common constituents, but their relative amounts vary widely.
This variability is striking enough that chemists have used turpentine composition as a tool for classifying pine species. A study of Eastern Mediterranean pines found that species like Pinus brutia, Pinus eldarica, and Pinus pityusa had very similar turpentine profiles, all containing significant 3-carene and sharing a levorotatory optical character. Pinus halepensis, by contrast, had a strongly different turpentine composition despite growing in overlapping regions. The researchers used these chemical fingerprints to argue that the first group of species is more closely related to Scots pine than to Aleppo pine.7Phytochemistry. Chemical composition of the turpentines of some Eastern Mediterranean pines in relation to their classification
For practical purposes, what this means is that turpentine from a slash pine plantation in the American South will behave somewhat differently from turpentine from a maritime pine forest in Portugal or a Masson pine stand in China. The alpha-pinene content, the smell, and the solvent strength all shift with the species. Buyers in industries that need specific terpene fractions care a great deal about the source species.
Separating Individual Terpenes
Crude turpentine, whether from gum or sulfate sources, is useful as a general solvent. But many of its highest-value applications require isolating individual terpene compounds. Alpha-pinene, for instance, is a starting material for synthetic fragrances, insecticides, and pharmaceutical intermediates. Limonene has its own market in cleaning products and food flavoring. To separate these, the turpentine is put through fractional distillation, often under vacuum to lower the boiling points and reduce the risk of thermal degradation.
Techno-economic modeling of this kind of separation, comparing continuous and batch vacuum distillation for isolating alpha-pinene from turpentine oil and d-limonene from citrus oil, has shown that the process is commercially viable but capital-intensive.8Chemical Engineering & Technology. Techno‐Economic Evaluation of d‐Limonene and α‐Pinene Separation from Citrus and Turpentine Oils The economics depend on how pure the fraction needs to be and how much throughput the facility handles. For large pine-chemical operations, continuous distillation is the norm. Smaller operations may use batch stills, accepting lower efficiency in exchange for flexibility.
What Turpentine Becomes
The image many people have of turpentine is a can of paint thinner in a garage, and that is still a real market. Artists and painters have used turpentine as a solvent for oil-based paints, varnishes, and cleaning brushes for centuries. But the chemical industry has found far more diverse uses for its individual terpene fractions.
Alpha-pinene, the most abundant component, serves as a building block for a surprisingly wide range of products. One well-studied pathway converts alpha-pinene into camphor through a series of chemical steps involving an intermediary isobornyl ester. Researchers have shown that a kinetic resolution step can be integrated into this process, allowing the production of optically pure camphor and useful monoterpene alcohols as side products, all from a renewable starting material.9Chembiochem / Wiley Online Library. Simple Plug-In Synthetic Step for the Synthesis of (-)-Camphor from Renewable Starting Materials Camphor itself goes into everything from moth repellents to topical pain-relief creams.
Beyond camphor, turpentine-derived terpenes are precursors for synthetic pine oil (used in household cleaners), polyterpene resins (used in adhesives and rubber), linalool and geraniol (used in perfumes and cosmetics), and insecticidal formulations. The pine-chemical industry essentially treats turpentine as a renewable feedstock for fine and specialty chemicals, which is why the push to improve resin yields and purification methods continues to attract research funding.
Gum Turpentine Versus Sulfate Turpentine
The two production routes serve somewhat different parts of the market. Gum turpentine from tapped trees tends to be purer, with a more pleasant smell and fewer contaminants. It commands a higher price and is preferred for fragrance applications, pharmaceutical intermediates, and any use where trace sulfur would be a problem. The downside is that tapping is labor-intensive. A worker must visit each tree repeatedly throughout the tapping season, make fresh cuts, and collect the accumulated resin. In countries where labor costs have risen sharply, gum turpentine production has declined.
Sulfate turpentine, by contrast, is essentially free raw material for any kraft pulp mill that processes pine wood. The terpenes would be released into the atmosphere or burned as fuel if they were not collected. This makes CST economically attractive despite the refining costs. China, Brazil, and Indonesia dominate global gum turpentine production because they have large pine plantations and lower labor costs. Northern Europe and North America produce more sulfate turpentine because their large kraft pulp industries generate it as a matter of course.
Historical Roots in the Naval Stores Industry
Turpentine production has deep historical ties to shipbuilding. For centuries, wooden sailing ships required pitch and tar to waterproof their hulls, and turpentine to thin protective coatings. These products, collectively called “naval stores,” were so strategically important that European colonial powers actively promoted pine-forest exploitation in their territories. The southeastern United States became a major center of the naval stores industry, with longleaf pine forests supplying vast quantities of resin through the 18th and 19th centuries.10Treesearch (U.S. Department of Agriculture, Forest Service). Naval stores: A history of an early industry created from the South’s forests
The methods used in that era were cruder than modern tapping. Workers would hack large “cat faces” into the trunks of longleaf pines, creating deep wounds that scarred the tree permanently and often shortened its life. The resin was collected in hollowed-out cavities at the base of the wound. Distillation was done in simple copper pot stills. The product was variable in quality and often contaminated with wood chips and charred material. The shift to more careful tapping techniques, chemical stimulants, and industrial-scale steam distillation transformed turpentine from a rough naval commodity into a refined chemical feedstock over the course of the 20th century.
Environmental Considerations
Turpentine production occupies an interesting position environmentally. On one hand, it is genuinely renewable. Pine trees regrow, oleoresin regenerates, and sulfate turpentine is recovered from an industrial waste stream that would otherwise be burned or vented. Compared to petroleum-derived solvents, turpentine has a smaller carbon footprint in principle because the carbon in its molecules was recently fixed from atmospheric CO₂ by the tree.
On the other hand, turpentine is a volatile organic compound, and its evaporation contributes to ground-level ozone formation just like petroleum-based solvents do. Industrial handling and distillation generate emissions that need to be controlled. A review of the environmental effects of terpenoid chemicals found that few cases of significant air pollution could be traced to terpene processing operations, though emissions from related wood-processing activities like veneer drying can cause localized odor problems.11Journal of the American Oil Chemists’ Society. Environmental effects of terpenoid chemicals: a review
Health-wise, turpentine is a skin and respiratory irritant. Prolonged or heavy exposure to its vapors can cause headaches, dizziness, and kidney irritation. The push in art conservation and painting toward less toxic solvents has led to research on alternatives. A recent study tested greener solvents like isoamyl acetate and anisole as replacements for turpentine in dissolving and applying picture varnishes, finding that several alternatives provided good working properties and visual results on actual paintings.12Nature Publishing Group. An innovative methodology for testing and selecting greener solvents for varnishing paintings For industrial chemical synthesis, though, there is no single drop-in replacement for turpentine’s terpene content, since those terpenes are the actual product, not just a carrier.
Wood Turpentine and Other Minor Sources
Besides gum turpentine from tapping and sulfate turpentine from kraft mills, a third type called wood turpentine exists. This is produced by destructive distillation or solvent extraction of pine stumps and other resinous wood waste. The stumps of old-growth longleaf pines, left behind after logging, were once a major feedstock for this process in the American South. The stumps were chipped, loaded into retorts, and heated to drive off the terpenes along with other wood-derived chemicals like pine tar and charcoal. Solvent extraction using naphtha was another common approach.
Wood turpentine production has declined sharply as the supply of old resin-rich stumps has dwindled and the economics have shifted in favor of sulfate turpentine. It still exists as a niche product, and the basic chemistry is the same: heat drives volatile terpenes out of resinous pine material. But it tends to contain more impurities than either gum or sulfate turpentine, including phenolic compounds from the wood itself, which limits its applications without extensive refining.
A fourth, even more minor source is sulfite turpentine, recovered from sulfite pulping mills. This process is far less common than kraft pulping today, so sulfite turpentine is a small fraction of the global supply. Its composition and quality issues are broadly similar to those of sulfate turpentine, though the specific sulfur compounds differ because of the different pulping chemistry.