Non-Toxic Paint Thinners (Safer Solvents)

This article looks at safer solvents that can act as a substitute for toxic solvents like mineral spirits, turpentine, methyl ethyl ketone, acetone, toluene, xylene, glycol ethers, and fluorinated or chlorinated organic solvents.

This article provides a list of alternatives that are non-toxic or less toxic. Many of them are all-natural. But natural does not necessarily equate to safer – turpentine after all is an all-natural product.

I also list one solvent-free option for cleaning brushes used with oil paints. That’s a fantastic way to limit your solvent exposure.

The solvents in the article are often referred to as paint thinners but the products I list have many uses:

• Thin oil-based paint to make it easier to apply or to extend its life
• Make spray applications of oil paint easier
• Clean up brushes, rollers, and equipment used with oil paints and varnishes
• Wipe up oil paint splatter
• Thin tung oil
• Clean and degrease metal equipment or parts
• Remove graffiti
• Remove tar, asphalt, gum
• Clean up caulking
• For artists working with oil paints – to produce special effects, and to change the way oil paints handles and evaporates
• Use with pastels, encaustic, oil-based colored pencils, letterpress, and sculptural work

Though some of these alternative solvents are only marketed towards one use, I will note what each solvent can be used for. Do note that once we get into solvents made for and marketed towards artists, the transparency of what’s in them goes way down and some of them are misleading consumers.

So let’s take a closer look at each product, its uses, toxicity rating, and tolerability for sensitive folks.

Expert Review: The toxicity sections were written by Dr. Lakshmi Manjunath, board certified toxicologist (US and Europe).

This post contains affiliate links. Upon purchase, I make a small commission at no extra cost to you.

1. 100% Citrus Solvent

Citrus Solvent is an all-natural alternative to harsh paint thinners. It is a clear formula, made from orange peels, used to thin oil paint, clean paint off brushes and equipment, thin tung oil, and for artist oil painting effects.

It can act as a substitute for mineral spirits, methyl ethyl ketone, acetone, toluene, xylene, glycol ethers, and fluorinated or chlorinated organic solvents.

It’s also used to clean and degrease. And it’s a food-safe option to mix with tung oil.

Citrus Solvent volatilizes a bit slower than mineral spirits and other harsh solvents, though it can usually act as a replacement for them.

What’s in it:

The product is made of citrus oil that is extracted from orange peels. There is nothing else added other than the 2% water that remains from the steam extraction. Citrus oil is mostly composed of d-limonene.

Toxicity:

Ventilation is recommended, especially when it’s in high concentrations. It is oxidized in the air to secondary organic aerosols consisting of aldehydes, acids, oxidants and fine and ultra-fine particles. These chemicals are pulmonary irritants inducing distinct inflammatory responses in younger and older animals. (Source)

D-Limonene has been designated as a chemical with low toxicity based upon acute and repeated-dose toxicity studies when administered orally to animals. But skin irritation or sensitizing potential was reported following widespread use of this agent in various consumer products.

However, healthy humans exposed by inhalation in a chamber to d–limonene did not experience any irritative symptoms or symptoms related to the central nervous system. (Source)

The official stance is that other than adverse dermal effects, there are no other notable toxic effects of d-limonene for humans (Source). I personally need to use a half facepiece chemical respirator with an organic solvent cartilage if I’m using a substantial amount of this since I’m chemically sensitive.

Uses:

• Thin paints
• Clean brushes
• Thin tung oil
• Heavy duty degreaser. It’s an alternative to CFC-laden cleaners, engine degreaser (automotive, aircraft, and aerospace industries), tar and asphalt remover, and graffiti remover.
• Artists can use this as a solvent in oil painting. Citrus Solvent does not volatilize as quickly as Odorless Mineral Spirits, so it will give you more working time. The Citrus Solvent is also used to clean brushes and palettes. 

Where to Buy: The Real Milk Paint Company, use code mychemicalfreehouse for 10% off. Also on Amazon.

2. Odorless Mineral Spirits

Odorless mineral spirits are a petroleum distillate. Compared to regular mineral spirits, the dearomatized varieties have gone through refining to remove the more pungent aromatic compounds.

Not all odorless mineral spirits on the market are the same, The Real Milk Paint brand of Odorless Mineral Spirits is significantly lower in odor than many others. They claim that is because it’s highly filtered and they don’t use benzenes to produce it.

Technically, it has a mild hydrocarbon smell (which will be noticeable to those who are chemically sensitive), but to many people, this really does not have a smell. It is definitely a lot less bothersome than regular mineral spirits.

This is another all-purpose thinner for cleaning up brushes and accessories, thinning oil-based paints, thinning tung oil, and cleaning sticky oil residue. It is an alternative to turpentine.

What’s in it:

Dearomatized mineral spirits (hydrocarbon solvents in the C10–C13 aliphatic carbon number range) with aromaticity of (<2%), CAS number 68551-17-7.

Toxicity:

It’s recommended that you wear a full facepiece chemical respirator with an organic vapor cartridge.

Isoparaffins have a very low order of acute toxicity, being practically non-toxic by oral, dermal and inhalation routes.

No symptoms associated with solvent exposure were observed when human volunteers were exposed for six hours to 100 ppm isoparaffin. No clinically significant renal abnormalities have been found in refinery workers exposed to hydrocarbons and isoparaffins were neither embryotoxic nor teratogenic.

On the SDS sheet, it says it’s not listed as a carcinogen or endocrine disruptor; that this product is not expected to cause reproductive or developmental effects, and that it may cause drowsiness and dizziness (central nervous system effects).

Toxicity studies have shown minimal to no systemic effects with exposure to dearomatized solvents like odorless mineral spirits (Source).

There is some evidence that dearomatized mineral spirits have less effect on the central nervous system (CNS) than the higher aromatic mineral spirits. (Source)

Uses:

• Thinning oil paint – for use on small details, for blending purposes, or projects when thicker paint might leave tell-tale brush strokes. To use your Odorless Mineral Spirits as an oil paint thinner, follow the ratio of thinner to paint recommended by the paint manufacturer. Mineral Spirits should be added slowly and mixed in thoroughly to prevent over-thinning.
• Cleaning brushes and other equipment after using oil-based paints and varnishes.
• Thinning tung oil.
• Cleaning or degreasing machinery or other metal parts.
• Dissolving oils to create a fresh surface for painting, varnishing, or similar refinishing work.
• Artists “can use it to clean an oil painting prior to varnishing by gently wiping the surface of the painting with a soft cloth very lightly moistening it. There should be no adverse effects from this procedure if the painting has had at least six months to cure” (Source).

Where to Buy: The Real Milk Paint directly – use code mychemicalfreehouse for 10% off.

Similar: Klean-Strip Green Paint Thinner is a very similar petroleum distillate/mineral spirit called Isopar (CAS number 64742-47-8). Both Isopar and the Odorless Mineral Spirits above are dearomatized mineral spirits which are also called odorless mineral spirits. More specifically, they are both hydrocarbons having carbon numbers predominantly in the range of C9 through C16 with less than 2% aromatic constituents.

Klean-Strip functions the same as Odorless Mineral Spirits in terms of thinning, cleaning, and prepping, and “because of the compositional similarities, the substances… have common metabolic pathways and, with a few well characterized exceptions, similar toxicological properties within a defined carbon number range.” (Source)

3. Mix: Citrus Solvent + Mineral Spirits

A solvent that is a mix of the above two options could suit you if citrus oil alone is too fragrant for you but you do want to go with something partially natural and avoid going with 100% mineral spirits.

Eco-House Extra Mild Citrus Thinner is a mix of orange oil and dearomatized mineral spirits, it’s marketed more at artists but really it is a good all-purpose thinner.

What’s in it:

It’s a mix of orange oil (9%) and two different kinds of dearomatized mineral spirits (CAS number 64764-47-8 at 12%, and CAS number 64742-48-9 at 79%).

Toxicity:

A mix of the toxicity ratings listed above under citrus solvent and dearomatized mineral spirits.

Uses:

This is an all-purpose paint thinner just like mineral spirits or citrus oil separately. It’s used on oil-based products, varnishes, waxes, resins, gums, and tars.

• For thinning and clean-up of all Eco-House brand oils, resins, varnishes, and waxes.
• Thinning and clean-up of oil-based conventional paint products.
• Cleaning up tars, gums, caulking, etc.
• For artists used in oil painting and pastels, encaustic, blending oil-based colored pencils, letterpress, and sculptural work. It dries slower than turpentine, keeping the paint workable for a longer period of time.

Where to Buy: Walmart online

Similar: BioShield Citrus Thinner is a similar formula. It is also a mix of orange oil (10%) and mineral spirits, in this case, Isopar, one of the dearomatized mineral spirits (CAS number 64742-47-8, assuming at 90% since they list no other ingredients).

It’s marketed for use with BioShield’s natural oil-based products and used in cleaning and degreasing: to dissolve oil stains, grease, tar, gums, waxes, resins, and glues; to clean greasy kitchen stoves, bicycles, resinous woods, crayon marks, machinery, tools, and other equipment. But it’s also used by professional painters and artists to thin oil-based paints and finishes and to clean brushes.

Note: this is not water-based as it says on one listing. It’s solvent-based. Calling it a replacement for petroleum-based mineral spirits in the listings is misleading since it is based on (dearomatized) petroleum mineral spirits. It is a replacement for regular mineral spirits, which are more aromatic.

4. Linseed Oil Soap

Linseed oil soap is the only non-solvent option on this list. It’s certainly the safest option for cleaning brushes used with artist oil paints or linseed oil-based house paint.

What’s in it: Linseed oil, soap.

Toxicity: Not toxic when used as intended. The safest option on the list for cleaning brushes.

Uses:

• Clean brushes used with linseed oil-based paint.
• Remove dried oils, acrylics, watercolors, and other artist paints from brushes if you soak overnight.
• Remove artist’s paints from clothing.
• Clean your hands, floors, and work surfaces after oil painting.

Where to buy: Amazon

Similar: Chelsea Classical Studio Lavender & Olive Oil Soap works in a similar fashion to clean oil paint off brushes. They say the ingredients are olive oil, water, lye, lavender oil, and wax and that it is all-natural. However, their spike lavender oil also says “natural” but it isn’t actually all-natural.

5. Soy-Based Solvent

Eco-Solve by Natural Earth Paint is a soy-based solvent. It dries slower than mineral spirits or other chemical paint thinners though it is generally a replacement for conventional solvents. It’s marketed at artists.

This is a mild solvent (in terms of odor) compared to the other options out there. I would consider this next after the above options if those don’t work for you. It might also be preferred for artists’ effects since it’s lower odor than citrus solvent, and less toxic than mineral spirits.

What’s in it:

The ingredients are listed as soybean oil and soybean esters. They also say “this product is soy oil that has had the fatty acids removed”; though all ingredients are trade secrets.

It’s possible to make a bio-based solvent distilled from soybean oil called methyl soyate, a methyl ester solvent. I can’t say for sure that that is what this is, but that would be my guess. That could be the soy ester component.

They claim it’s 100% natural and the SDS lists it as biodegradable.

Toxicity:

“Aquatic toxicity rating not determined. All possible measures should be taken to prevent release into the environment”. (SDS)

Methyl soyate has low toxicity through oral and dermal exposure. It is non-irritating to skin and eyes. However, it has moderate skin sensitization potential. It has low or no carcinogenicity activity, developmental and reproductive toxicity and it is classified as not expected to be potentially toxic or harmful.

The SDS also says: “May cause respiratory irritation.” You should use it in a ventilated space and use a NIOSH-approved dust/particulate respirator (like an N95), according to the SDS sheet. Those are good signs, that it doesn’t require a half-face or full-face respirator, and that it only causes irritation – but, it’s not totally benign.

Reviews are mixed. Among those who are sensitive, some do well with Eco-Solve and have no problem using it inside, and some found it stronger than expected and even got headaches.

Uses:

For artists working with oil paints, this helps to remove the paint from brushes, palettes, containers, and work surfaces. It’s excellent for creating washes, under-paintings, glazes, drip effects, etc.

Where to Buy: Amazon

Similar? Sennelier Thinner states it’s bio-solvent based and made from sustainable raw materials such as vegetable oils and grain. I have no idea what that means in terms of what it actually is. Reviews mention it has an oak odor.

6. Lavender Spike Oil

Citrus oils are the most common and most affordable of the plant-based natural solvents, and soy solvents are probably the lowest odor plant-based solvent, but spike lavender oil is another natural extract that acts as a solvent. 

Just note that spike lavender oil refers to both the natural essential oil and the artist solvents, which appear to be entirely or partially synthetic.

It is a strong, slow drying solvent, with thinning properties similar to turpentine. It is used to thin oil paints as well as varnishes and resins, and as a medium.

It has a fairly strong scent, but it is less offensive than turpentine. This is used primarily by artists, since it’s pricey.

What’s in it:

True spike lavender oil, is an essential oil made from the Lavandula latifolia plant. The main constituents of this less common lavender variety are: linalool (27.2–43.1%), 1,8-cineole (28.0–34.9%), camphor (10.8–23.2%), borneol (0.9–3.6%), β-pinene (0.8–2.6%), and (E)-α-bisabolene (0.5–2.3%) (Source).

Note that lavender spike oil that is sold as a solvent for painters is not likely to be a 100% natural extract, but it could be a synthetic version of similar components (i.e. synthetic camphor, etc.) or adulterated natural oils.

Toxicity:

There’s a difference between the toxicity of natural spike lavender oil and synthetic versions (which is what the artists’ solvents appear to be).

Lavender spike oil (the natural version) caused sensitization in humans and animals and respiratory system, eyes, GI and skin are target organs for its sensitization. The potential for idiosyncratic allergenicity may exist and should be forewarned, but this effect would be readily identified and reversible Lavender oil (in this experiment Lavandula angustifolia) is cytotoxic to human skin cells in vitro (endothelial cells and fibroblasts). The major component of the oil, linalyl acetate is responsible for its activity. Adverse effects during pregnancy are unknown but assumed minimal given the history of product use

The synthetic versions of the chemicals that imitate spike lavender oil are toxic. Linalool is not considered toxic but oxidized Linalool is; Eucalyptol is slightly toxic when inhaled; Terpineol, alpha and beta pinene are components of turpentine which is considered the most toxic of traditional solvents; and Camphor has effects on the central nervous system and kidneys, and inhalation can cause respiratory depression and apnea. 

Uses:

Spike Lavender works well as an alternative to thinners like turpentine and odorless mineral spirits for artists:

• It thins oil paints, mediums and varnishes in the same way that odorless mineral spirits would do.
• “Often, a painter will use it to promote a smoother brush stroke. Historically, it has been used in mixtures with pigments such as sienna to “tone” the canvas without actually putting down a layer of paint.”
• “Spike Lavender works quite well to remove a stroke of paint on the canvas, correcting a problem on the painting.”
• “Used on its own for wet and thin underpainting, it produces a very smooth matte finish.” (Source)
• To blend colored pencils.
• It can be used to clean oil paint brushes, though it would make a very pricey brush cleaner.

Where to buy:

Edens Garden brand on Amazon is a true spike lavender essential oil. They provide GC/MS reports to customers to ensure each oil’s purity. While this type of real spike lavender oil used to be used by artists back in the day, current advice on using spike lavender oil in artist painting uses the synthetic version as a reference. Please get advice from other artists on using the true essential oil for painting.

Chelsea Classic Studio Lavender Spike Oil Essence is the most popular brand for artists in North America. It does say “natural solvent” and “made from natural extracts”, but that seems misleading to me. An email from Brandon Sokkol to Tad Spurgeon states “ours is not 100% naturally distilled Lavender Latifolia Flowers.” On the other hand, the SDS does say that it is 100% natural extracts (CAS 8016-78-2). The description also states: this thinner for oil paint has been made without the use of heavy chemicals like turpentine, though it’s heavy on terpenes like those found in turpentine. It does smell fairly strong (and like lavender) but it does not smell as strong as spike lavender essential oil. The SDS states that no protective gear or ventilation is needed (however that SDS sheet is reporting on 100% natural extracts and the email from them said it’s not 100% natural).

Those that didn’t quite make the list…

Pine Oil

Turpentine is an all-natural product made from the distillation of pine sap harvested from living trees. However, the toxicity is high which is why it didn’t make the list.

Wood turpentine is obtained by the steam distillation of pine wood, while gum turpentine results from the distillation of the resin (sap) of the living pine tree obtained by tapping.

Since wood turpentine is made using heavy naphtha fraction, gum turpentine is preferred as the all-natural option.

What’s in it:

Turpentine is composed of terpenes, primarily the monoterpenes alpha- and beta-pinene, with lesser amounts of carene, camphene, dipentene, and terpinolene. (Source)

Toxicity:

Turpentine vapor can irritate the skin and eyes, damage the lungs and respiratory system. Exposure can cause headaches, nausea, and vomiting. High exposures via inhalation affect the central nervous system.

A full facepiece with organic vapor cartilage is recommended if the exposure potential is over 20 ppm.

(Source and Source)

Uses:

• Paint thinning, brush cleaning.
• Artists – gum turpentine speeds up drying unlike mineral spirits or spike lavender, which are slower drying solvents. Gum turpentine will thin oil paints and remove dried oil paint that is not well cured. When mixed in with oil paints, it could increase the tendency to yellow with age.

Green Envy Paint Thinner

Green Envy Paint Thinner is used for thinning oil-based and latex paint products, cleaning brushes and rollers after painting, and degreasing surfaces. This thinner is water-based and the company describes it as low odor.

It is technically low VOC at 19 g/l, however, one of the solvents is not being counted in this VOC rating.

It didn’t quite make my list because of the toxicity ratings of the solvents in it.

What’s in it:

Parachlorobenzotrifluoride (CAS 98-56-6) 5% – a solvent with a distinct aromatic odor. It is an exempt VOC (that is to say this is a volatile organic compound but it does not need to be included in the VOC rating of the product). A solution only needs a small percent (5% in this formula) to function well as a solvent, which helps reduce the overall levels of VOCs in the product. There is very little data available in terms of toxicity, though it does have the typical toxicity warnings for harsh solvents (source).

Naphtha (CAS 64741-65-7) 5% – this is a petroleum distillate solvent with a gasoline-like odor that is more aromatic than odorless mineral spirits.

Di(propylene glycol) methyl ether (CAS 34590-94-8) 5% – is an organic solvent a less volatile alternative to propylene glycol methyl ether and other glycol ethers. It has a mild ether-like odor.

Dioctyl sulfosuccinate sodium salt (CAS 577-11-7) 5% – a surfactant that can be used pharmaceutically (as a laxative).

Toxicity:

The vapor of this product is harmful. Avoid breathing vapor or spray mist. May affect the brain or nervous system causing dizziness, headache, or nausea. Causes eye, skin, nose, and throat irritation. Open doors and windows to provide plenty of fresh air ventilation during application and drying. (SDS)

4-chloro-α,α,α-trifluorotoluene has low acute toxicity through oral, dermal and inhalation toxicity study. It is not a skin irritant and or eye irritant and it is not skin sensitizer.

Dipropylene glycol monomethyl ether has low acute toxicity through oral, dermal and inhalation. No irritation of skin or eye has been reported. No sensitization reaction was observed with dipropylene glycol methyl ether

Sodium dioctyl sulfosuccinate has been designated as a chemical with low to moderate toxicity based upon acute and repeated-dose toxicity studies when administered orally or inhalation exposure to animals. But skin/eye irritation or sensitizing potential was reported following widespread use of this agent in various consumer products.

Where to Buy: Walmart (online)

Corinne Segura is a Building Biologist Practitioner with 8 years of experience helping others create healthy homes.

The toxicology sections were written by Dr. Lakshmi Narayana Manjunath, American board certified (DABT) and European Registered Toxicologist with more than 12 years of experience working in the pharma, cosmetic and medical device industries.