The jar on most oil painters’ tables holds a clear liquid that barely smells of anything, which leads a lot of beginners to assume it is gentle, maybe even something close to water. It is not. Knowing what is odorless mineral spirits, what was removed to make it odorless and what was left behind, helps you use it for what it is good at and avoid treating it more casually than you should.
Quick answer: Odorless mineral spirits (OMS) is a petroleum-based solvent made of aliphatic hydrocarbons, refined to remove most of the aromatic compounds that give ordinary mineral spirits and paint thinner their strong smell. Oil painters use it to thin paint, mix mediums and clean brushes. “Odorless” means low odor, not harmless: it still evaporates into the air and is flammable, so it should always be used with ventilation.
What Odorless Mineral Spirits Is Made Of
Mineral spirits are distilled from crude oil. Standard mineral spirits contains a mix of hydrocarbon types, including aromatic hydrocarbons, a family that includes compounds such as toluene and xylene. Aromatics are strong solvents, but they also carry most of the sharp, chemical smell and are generally considered more hazardous to breathe.
Odorless mineral spirits goes through further refining, often hydrotreating, that removes most of those aromatics. What remains is largely aliphatic hydrocarbons: straight-chain and branched molecules that evaporate steadily, dissolve oil paint well enough for painting and smell faintly or not at all.
Artist-grade OMS is typically refined further than hardware versions to keep the aromatic content very low. Labels vary in how much detail they provide, so the safety data sheet is the most reliable place to check composition. Our comparison of odorless mineral spirits made for artists looks at how the common studio options differ.
Why “Odorless” Does Not Mean Safe
Your nose is a warning system, and odorless mineral spirits switches it off. You can be breathing solvent vapor without noticing it. Removing aromatics lowers the hazard, but it does not remove it entirely.
- Vapor is still released. OMS evaporates; that is how it leaves your paint. The vapor goes into the room air.
- It is flammable. Keep it away from open flames, pilot lights, sparks and heaters.
- It irritates skin. Solvents remove natural oils from skin, which can cause dryness and dermatitis with repeated contact.
- It should never be swallowed or left where children or pets can reach it.
Treat OMS as a low-odor solvent, which is what it is, rather than a non-toxic one.
Odorless Mineral Spirits vs Other Solvents
| Solvent | Base | Odor | Strength | Typical Use |
|---|---|---|---|---|
| Odorless mineral spirits | Petroleum, aromatics removed | Very low | Moderate | Thinning oil paint, mediums, brush cleaning |
| Regular mineral spirits | Petroleum with aromatics | Noticeable | Moderate to strong | Hardware cleanup, degreasing |
| Paint thinner | Varies; often less refined mineral spirits | Strong | Varies | House painting cleanup |
| Gum turpentine | Distilled pine resin | Strong, piney | Strong | Traditional mediums, dissolving natural resins |
| Citrus-based solvent | Orange peel oil (d-limonene) | Strong citrus | Strong | Alternative thinner; can irritate skin |
Gum turpentine is a stronger solvent and dissolves natural resins like damar more readily. OMS is milder, which some painters prefer for everyday thinning, and it evaporates a little slower, giving a bit more working time in thinned passages.
How Odorless Mineral Spirits Is Used in Oil Painting
Thinning paint for early layers
Mixing a small amount of OMS into oil paint makes it thinner and leaner. This is ideal for sketches, toned grounds and underpaintings, which should dry faster and contain less oil than later layers under the fat-over-lean principle.
Making mediums
OMS is combined with linseed or stand oil, and sometimes with resins or alkyds, to make custom mediums. A simple starting medium for middle layers is roughly one part oil to two parts OMS.
Cleaning brushes
Rinsing brushes in OMS removes most paint quickly. Follow with soap and water to remove the remaining oil and pigment.
Wiping back and corrections
A rag dampened with a little OMS lifts wet paint for corrections or highlights, and softens edges.
Cleaning palettes and tools
OMS on a paper towel clears glass palettes and palette knives at the end of a session.
How to Use Odorless Mineral Spirits Step by Step
- Ventilate first. Open a window and, ideally, run a fan that pushes air out of the room rather than circulating it.
- Use a lidded container. A small glass or metal jar with a tight lid, or a brush washer with a coil, keeps evaporation down.
- Pour only what you need. A few tablespoons are enough for thinning and rinsing during a session. Close the main bottle.
- Thin paint sparingly. Dip the brush, then touch it into the paint. Add more only if the paint is still too stiff.
- Rinse brushes, then wipe. Swirl in OMS, press bristles on the coil or jar side, and wipe on a rag.
- Keep the jar closed between rinses. This is the single biggest habit that reduces vapor in the room.
- Finish with soap. Wash brushes with mild soap and lukewarm water and reshape them to dry.
- Store dirty OMS to settle. Pigment sinks over a few days, and the clear spirits on top can be reused.
How Much OMS to Mix Into Paint
| Stage | OMS Use | Why |
|---|---|---|
| Toned ground or sketch | Generous; paint thinned to a wash | Fast drying, very lean |
| Underpainting | Moderate; paint loose but not runny | Stays lean so later layers can be fatter |
| Middle layers | As part of a medium, roughly 2 parts OMS to 1 part oil | Balance of flow and flexibility |
| Final layers and glazes | Little or none | Keeps top layers fat and flexible |
Over-thinning is a real risk. Too much solvent dilutes the binder so much that the dried paint can become chalky, powdery or underbound, particularly over an absorbent ground.
Evaporation Rate and Why It Matters
Different solvents leave paint at different speeds. Odorless mineral spirits generally evaporates more slowly than gum turpentine and much more slowly than fast solvents like acetone. This has practical effects on the easel.
- Longer working time in thin layers. A wash thinned with OMS stays workable a little longer, which helps when blocking in large areas.
- Slightly slower surface set. A very solvent-heavy underpainting may need a few extra hours before it is ready for the next layer, compared with turpentine.
- Lingering vapor. Because it evaporates over a longer period, vapor is released gradually throughout the session, another reason to keep jars closed and air moving.
Products differ in their exact evaporation rate depending on how they are refined, and manufacturers’ safety data sheets often list the relevant figures if you want to compare.
Solvent Strength and Resin Mediums
Solvents vary in how aggressively they dissolve resins and dried paint. Because the aromatics have been removed, OMS is a milder solvent than regular mineral spirits or turpentine. In daily painting this is mostly an advantage: it is less likely to disturb a dry underlayer when you glaze over it.
The downside shows up with certain traditional recipes. Natural damar resin, for example, dissolves more completely in turpentine than in many odorless spirits, and mixtures made with OMS can turn cloudy. If you follow an old medium recipe that calls for turpentine, test the OMS version on a small scale before committing to a batch. Alkyd mediums and modern varnishes are usually formulated to work with mineral spirits, so this is less of a concern with them.
Signs You Are Using Too Much
- The paint dries matte and patchy, sometimes rubbing off on a fingertip.
- Later layers lift or dissolve earlier ones.
- Drips run down the canvas on an upright easel.
- The room smells of solvent even with low-odor spirits; that means vapor levels are high.
Artist-Grade vs Hardware Odorless Mineral Spirits
Hardware stores sell products labeled odorless mineral spirits for house painters. Some are similar to artist versions; others contain more aromatics or additives, and labeling is not always detailed. Artist-grade OMS is generally refined for very low aromatic content and consistency, which matters because painters often use it daily in small rooms.
Look for a product sold for fine-art use and check its safety data sheet. Our roundup of the best odorless mineral spirits for oil painters compares artist options on odor, evaporation rate and refinement.
Safety and Studio Practices
- Ventilation: cross-breeze or an exhaust fan. A closed bedroom studio is the worst-case setup.
- Minimal exposure: small jars, lids on, no open buckets.
- Gloves: nitrile gloves help if you clean brushes often.
- Fire safety: no smoking, candles or space heaters near solvent. Store bottles away from heat and sunlight.
- Rags: rags with OMS and oil paint should be laid flat to dry outdoors or stored in a sealed metal container with water, because the oil in them can self-heat.
- Disposal: never pour used OMS down a drain. Let pigment settle, reuse the clear liquid, and take sludge to a household hazardous waste collection.
How to Read an OMS Label and Safety Data Sheet
Bottles rarely tell you much on the front. The safety data sheet (SDS), which manufacturers are required to provide and usually post online, is far more informative. A few sections are worth knowing:
- Composition. Look for the chemical description, such as “hydrotreated light petroleum distillates,” and any listed aromatic content. Lower aromatic content generally means lower odor and lower toxicity concerns.
- Flash point. The temperature at which vapor can ignite. Higher numbers indicate a somewhat lower fire risk at room temperature, but every mineral spirit is still flammable.
- Exposure controls. Recommendations for ventilation and gloves.
- Handling and storage. Guidance on keeping containers closed, away from heat and out of sunlight.
On the front label, phrases such as “for fine art use,” “low odor” and “aromatic-free” are helpful but are not standardized terms. The SDS is where you confirm them.
Storing Odorless Mineral Spirits
Keep OMS in its original, tightly closed container or in a clearly labeled metal or glass bottle meant for solvents. Store it in a cool, dry place away from sunlight, heaters, furnaces and water heaters with pilot lights. Never store it in a drinking bottle or food jar, where someone could mistake it for a drink.
Do You Even Need It?
Solvent is not mandatory in oil painting. Some painters work solvent-free, cleaning brushes with oil and soap, and using only oil-based or solvent-free mediums. This approach removes vapor from the studio entirely but requires discipline with the fat-over-lean principle, since you lose the easiest way to make early layers lean.
Most painters use a little OMS for the underpainting and brush rinsing, and nothing else. That is a reasonable middle ground.
Common Mistakes
- Leaving an uncovered jar of solvent next to the easel all day.
- Assuming no smell means no vapor.
- Over-thinning paint so the binder is too weak.
- Using hardware thinner with an unknown aromatic content in a small room.
- Pouring used spirits down the sink.
FAQs
How to use odorless mineral spirits for oil painting?
Use it to thin paint in early layers, mix it with oil to make a medium for middle layers, and rinse brushes during and after painting. Keep it in a lidded jar, use small amounts and ventilate the room.
Is odorless mineral spirits the same as paint thinner?
Not exactly. Paint thinner is a broad term, often for less refined mineral spirits with more aromatics and stronger odor. Odorless mineral spirits has most aromatics removed.
Is odorless mineral spirits toxic?
It is less hazardous than solvents with high aromatic content, but it is still a petroleum solvent. Vapors should not be breathed in an unventilated space, skin contact should be limited, and it must never be swallowed.
Can odorless mineral spirits replace turpentine?
For thinning paint and cleaning brushes, yes. Turpentine is stronger and dissolves natural resins like damar more readily, so some traditional medium recipes still call for it.
Does odorless mineral spirits evaporate completely?
Yes. It evaporates fully from paint, leaving the oil and pigment behind. That is why it makes paint leaner and faster drying.
Can I reuse odorless mineral spirits?
Yes. Let dirty spirits sit in a closed jar for several days until the pigment settles, then pour off the clear liquid into a clean container and reuse it.
Final Thoughts
Odorless mineral spirits is a refined petroleum solvent that thins oil paint and cleans brushes with far less smell than ordinary thinner. Respect it as a solvent and use it sparingly in a ventilated room. Choose an artist-grade product so you know what you are breathing. For specific picks, read our guide to low-odor mineral spirits for the studio.
