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What are Mineral Spirits?

Eric Tallberg
Eric Tallberg

Seasoned paint professionals today use a solvent called mineral spirits as an alternative to turpentine for thinning paint and cleaning paint brushes. Mineral spirits is a mild, low volatility petroleum distillate that can be used for degreasing and cleaning machinery and, along with cutting oil, as a lubricant for the cutting and reaming of screw threads.

Mineral spirits is also known as Stoddard solvent, referring to its co-inventor, W. J. Stoddard. In 1928, Stoddard, along with Lloyd Jackson, developed this alternative solvent for use in his dry cleaning business. Stoddard solvent remained the most popular dry cleaning solvent in America right through the 1950’s and the term is used most frequently in this context. Outside the U.S. and Canada, mineral spirits is called white spirit although it is actually a clear liquid.

Mineral spirits are often used as paint thinner.
Mineral spirits are often used as paint thinner.

In the distillation process, chemicals such as aliphatic (paraffin) and alicyclic (cyclo-propane) hydrocarbons are combined with alkyl aromatic (benzene) hydrocarbons to produce the three most common types of mineral spirits. Type I has been subject to hydro-desulfurization where most of the sulfur is removed from the distillate. Type II is basically a solvent extraction where hydro-treatment removes most aromatic hydrocarbons. Type III is processed with hydrogenation, the addition of hydrogen. What all this means is that the atomic structure of the various hydrocarbons which form the distillate of each type of mineral spirits have been interchanged for different applications.

A paint brush cleaned with mineral spirits.
A paint brush cleaned with mineral spirits.

Type II odorless mineral spirits is one of the most common types of paint thinner. It has been treated to remove aromatic solvents, allowing it to be used in the manufacture of low-odor oil-based paint. Mineral spirits in its aromatic form is, among its other uses, a basic ingredient in asphalt production.

In addition to typing, mineral spirits are categorized as class 1, 2 or 3. Class 1 is a product with a high flashpoint or burn temperature and, therefore, a low volatility rating. Class 2 has a somewhat lower flashpoint temperature and class 3, the highest volatility with, obviously, the lowest flashpoint of the three classes.

Mineral spirits are used in producing asphalt.
Mineral spirits are used in producing asphalt.

Though mineral spirits is one of the safer alternative cleaners and solvents, it is described by the Occupational Health and Safety Administration (OSHA) as a mild dermal irritant. It also receives a class 3 flammability rating; once its relatively high flashpoint is reached, mineral spirits will burn just like any hydrocarbon-based solvent, thereby emitting dangerous toxins. Additionally, chronic toxic encephalopathy, a brain ailment often found in commercial and residential painters, has been blamed on prolonged exposure to mineral spirits. Therefore, although mineral spirits is a far safer alternative to many solvents in certain applications, it should, like any petroleum distillate, be stored and handled with proper care.

Discussion Comments

shaney

My concrete driveway was sealed with Thompson water sealant. It was over applied (as their warning said not to do). I am looking for something to remove the excess as it is slippery to walk on. Would mineral spirits work in removing the excess? If not, what would?

anon112523

I use odorless mineral spirits to burn as fuel in Aladdin oil lamps. It burns clean and without odor.

anon77782

Odorless Mineral Spirits are a common substitute for turpentine in oil paints. They are less toxic by something like 1/3. They are also used in some cold wax concoctions, like Gamblin's cold wax medium.

Cold wax is generally not heated, but my interest is in a faux encaustic surface, so I've been using Dorland's cold wax, which purportedly does not use odorless mineral spirits (which have a low, dangerous, flash point, but rather uses resins). But I can't really find info on the particulars of the Dorland medium when it is heated.

Regardless, if you are doing encaustic or faux-encaustic paintings, the low flashpoint of odorless mineral spirits should be taken into account. It could be a safety hazard.

zoid

I've used mineral spirits as a way to blend colors. You can color an image with high-quality colored pencils, then use a little bit of mineral spirits on a cotton swab to blend it. It gives a really interesting look to drawings.

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    • Mineral spirits are often used as paint thinner.
      By: Coprid
      Mineral spirits are often used as paint thinner.
    • A paint brush cleaned with mineral spirits.
      By: Jiri Hera
      A paint brush cleaned with mineral spirits.
    • Mineral spirits are used in producing asphalt.
      By: Brilt
      Mineral spirits are used in producing asphalt.