Solvents thin paint, dissolve resins, and clean brushes. From turpentine to mineral spirits to citrus solvents, learn the history and science of painting solvents.
In 2026, an oil painter has more solvent choices than at any point in history. Turpentine, the traditional solvent distilled from pine resin, sits on the shelf next to odorless mineral spirits, low-odor mineral spirits, citrus solvents, and spike oil of lavender. Each has a different solvent power, evaporation rate, odor, and health profile. The choice of solvent affects how the paint flows, how fast it dries, how well it dissolves resins, and how safe the studio environment is. For most of oil painting's history, there was only one option. Now there are many, and knowing which to use for what is part of the craft.
A solvent is a liquid that dissolves another substance. In painting, solvents are used to thin paint (reduce its viscosity so it flows more easily), dissolve resins (to make varnishes and mediums), and clean brushes, palettes, and other tools of dried paint. Solvents evaporate completely, leaving no residue in the dried paint film. They are distinct from oils and resins, which remain in the paint and become part of the dried film. This distinction is the basis of the fat over lean principle: layers with more solvent (lean) dry faster and are less flexible, while layers with more oil (fat) dry slower and are more flexible.
This entry covers the types of solvents used in painting, their history, how they work chemically, and the health and safety considerations that have driven the shift from traditional to modern alternatives.
A solvent works by breaking the intermolecular forces between the molecules of the substance being dissolved. In oil painting, the substance being dissolved is the linseed oil binder (when thinning paint) or a natural or synthetic resin (when making mediums and varnishes). The solvent molecules interpose themselves between the oil or resin molecules, reducing the forces that hold them together and allowing them to spread apart. This reduces the viscosity of the paint or resin solution, making it flow more easily.
When the solvent evaporates, the oil or resin molecules come back together and the paint or varnish returns to its original concentration. In paint, the oil then begins its curing process (autoxidation and cross-linking). In a varnish or medium, the resin forms a solid film as the solvent leaves. Because the solvent evaporates completely, it does not become part of the dried paint film. It is a processing aid, not a permanent component.
Solvent power is measured by the Kauri-Butanol (Kb) value, which indicates how effectively a solvent dissolves a standard reference material. Higher Kb values mean stronger solvent power. Turpentine has a Kb value of approximately 56, making it a strong solvent that can dissolve both oils and natural resins like dammar and mastic. Odorless mineral spirits have a Kb value of approximately 28, making them a weaker solvent that can thin paint and clean brushes but cannot fully dissolve dammar resin. This difference in solvent power is the main reason turpentine is still used by painters who work with traditional resin-based mediums.
Evaporation rate is the other key property. Faster evaporation means the paint or varnish sets more quickly but also means more solvent in the air over a shorter period. Turpentine evaporates at a moderate rate. Mineral spirits evaporate more slowly. Naphtha evaporates faster than both. The evaporation rate affects both the working properties of the paint and the health risks of the solvent.
The use of solvents in painting is tied to the development of distillation technology. The distillation of pine resin to produce spirits of turpentine has ancient roots, but the systematic production of distilled solvents for use in painting begins in the late Middle Ages. A 2024 study by Leslie Carlyle traced the history of distilled oil of turpentine, finding that while distillation technology existed by the late 13th century, concrete evidence for the use of turpentine as a paint thinner before the early 16th century is scarce. The first detailed description of distilled oil of turpentine appears in Hieronymus Brunschwig's Grosses Distillierbuch, published in Strasbourg in 1512. Read the study at ResearchGate.
Until the advent of mineral spirits in the mid-20th century, turpentine was the standard solvent in painters' studios. It was used to thin paint, make spirit varnishes, and clean brushes. Its toxicity was common knowledge: the relationship between working around turpentine and coughing and shortness of breath was recognized even in earlier centuries. But there was no alternative, so painters used it.
The real demand for turpentine came not from artists but from the commercial painting and coatings industry, which emerged in the late 18th century. The British in particular began building with inexpensive wood from the colonies and wanted paint to protect and decorate it. The industrial demand for turpentine was met largely by production in the American South, where enslaved African labor was used to tap pine trees and distill the resin. The industrial use of turpentine far exceeded artistic use, and it was the industrial demand that drove the development of petroleum-based alternatives.
After World War II, solvents made from petroleum distillates replaced turpentine in industrial applications. Mineral spirits, a group of hydrocarbon solvents refined from crude oil, became the standard industrial solvent. Since the 1970s, increasingly better qualities of odorless mineral spirits have been produced, with the aromatic hydrocarbons (the most toxic component) refined out. In art studios, the shift from turpentine to mineral spirits has been more gradual, driven by health concerns and the availability of better-quality OMS products.
Distilled from pine resin, turpentine is the traditional painting solvent. It has the strongest solvent power (Kb 56) and is the only solvent that fully dissolves dammar resin. It evaporates at a moderate rate and has a strong, distinctive odor. Its main drawbacks are its health risks (respiratory irritation, sensitization, low flash point) and its cost relative to petroleum-based alternatives. Double or triple distilled turpentine is water-clear and produces the best results. "Cheap turps" contains approximately 20% resin debris that slows drying and compromises paint film quality.
Distilled from petroleum, mineral spirits are the most common solvent in industrial painting. They come in three grades: regular odor (about 75% of all solvents used in the paint industry, containing 15-25% aromatic hydrocarbons), low odor (predominantly heptane and octane with small amounts of xylene and toluene), and odorless (aliphatic compounds with the aromatic fractions removed). Odorless mineral spirits (OMS), such as Gamblin's Gamsol, are the most popular turpentine alternative in art studios. They have a Kb value of approximately 28, a higher permissible exposure level (300 ppm versus 100 for turpentine), and slower evaporation. Their main limitation is that they cannot fully dissolve dammar resin.
Distilled from the spikes of a lavender species, spike oil was used as a paint solvent since the Renaissance. It has a slower evaporation rate than turpentine, which gives it different working properties. Some painters prefer it for its gentler action on the oil binder: it thins paint without breaking the bond between pigment and oil as aggressively as turpentine. It has a strong floral odor and is more expensive than both turpentine and mineral spirits.
Derived from orange peel (primarily D-limonene), citrus solvents like Zest-It offer a middle ground between turpentine and mineral spirits. They have a pleasant citrus odor, lower toxicity than turpentine, and can dissolve dammar resin, making them a genuine turpentine substitute for traditional medium recipes. They are more expensive than mineral spirits but popular among painters who want traditional solvent performance without turpentine's health risks.
A more refined petroleum distillate than mineral spirits, VM&P (varnish makers and painters) naphtha evaporates faster and is used when quicker drying is needed. It is less common in art studios than in industrial finishing but is sometimes used by painters who want fast-evaporating solvents for underpainting.
All solvents used in painting are toxic to some degree. The health risks depend on the specific solvent, the concentration in the air, the duration of exposure, and the route of exposure (inhalation, skin contact, ingestion). The permissible exposure level (PEL), measured in parts per million, indicates how much solvent vapor can be in the air before health effects are expected. Higher PEL values mean safer solvents.
Turpentine has a PEL of 100, the lowest of the common painting solvents. Its alpha-pinene component is a respiratory irritant and sensitizer, meaning repeated exposure can cause allergic reactions. Turpentine also has a low flash point of approximately 35 degrees Celsius, making it flammable.
Mineral spirits have a PEL of 300, making them three times safer than turpentine by this measure. Odorless mineral spirits are the safest of the petroleum-based solvents because the aromatic hydrocarbons (the most toxic component) have been removed. However, OMS has a paradoxical risk: because it has no odor, painters may not realize they are being exposed to solvent vapors. The lack of smell does not mean the solvent is harmless. It means the warning system that smell provides has been disabled.
The basic safety practices for solvent use are straightforward: work in a well-ventilated space, keep containers closed when not in use, avoid skin contact, and dispose of used solvent properly. For painters who work in home studios or shared spaces, the choice of solvent should prioritize low toxicity and low odor, which points toward OMS or citrus solvents rather than turpentine.
Solvents are one of the three components of painting mediums, alongside oils and resins. Turpentine is the traditional solvent, while mineral spirits and citrus solvents are modern alternatives. Solvents are used to thin paint in the fat over lean system and to dissolve resins for varnishes and glazes. For more on how solvents fit into oil painting practice, read our post on oil painting, glazing, and impasto, or explore our guide to reading a painting.
Solvents evaporate completely, so you cannot see them in a finished painting. What you can see is their effect on the paint surface. Thin, lean underpainting, made with a high proportion of solvent, produces a matte, flat surface that adheres well to the ground. Thick, fat paint, made with little or no solvent, produces a glossy, textured surface that sits on top of the underpainting. The contrast between these two surfaces, visible in paintings from Rembrandt to Sargent, is a product of solvent use.
For more on painting materials, read our entries on turpentine and linseed oil, or explore our post on plein air painting and its materials.
Discover other art terms you might be interested in
A binder is the substance that holds pigment particles together and adheres them to a surface. From animal glue to linseed oil to acrylic, learn binder history and types.
The ground is the preparatory layer applied to a painting support before painting. From medieval gesso to modern acrylic primer, learn its history, types, and function.
Lightfastness measures how well a pigment resists fading under light. Learn how the Blue Wool scale, ASTM ratings, and microfade testing protect art from irreversible color loss.
Read more about this topic on our blog
Discover why acrylic paint is the best medium for beginner artists. Learn essential techniques, materials, and tips from artists like David Hockney and Mark Rothko who built careers on this versatile medium.
The art school vs. self-taught debate generates more heat than light. This guide cuts through the rhetoric to explain what art school actually gives you, what it doesn't, and how self-taught artists can build what school would have provided.
Understand the art of oil painting, from Van Eyck's luminous glazes to Van Gogh's thick impasto. Learn why oil paint has been the dominant medium for five centuries and how its unique properties work.