Mineral Spirits vs. Paint Thinner: What's the Difference?

Mineral Spirits

Lee Wallender

Water-based latex paints have evolved and have become more prevalent in the home to the point where oil-based products are used less frequently. Yet some professional painters and do-it-yourselfers still prefer oil-based paints for their ability to self-level and remain streak-free. Plus, most stains and varnishes are still oil-based, as well. Water cannot be used as a solvent for any of these products.

Mineral spirits and paint thinner are indispensable solvents for thinning oil-based paint, stains, and varnishes, as well as for cleaning up paint equipment and oily materials. Is there any difference between mineral spirits and paint thinner? If so, which of the two should you purchase?

Mineral Spirits vs. Paint Thinner

  • Mineral spirits is a term that specifies the product's composition; paint thinner is a generalized term that describes the product's function, not its composition.
  • Mineral spirits are made of 100-percent petroleum distillates and have no additives; mineral spirits-based paint thinners are often blended with additives such as trimethyl benzene (benzene).
  • Mineral spirits tend to be lower in odor than paint thinners.
  • Mineral spirits are often priced higher than paint thinners.
  • As a general term, paint thinner can mean anything that thins or cuts paint, including products advertised as safe, green, or eco-friendly that have as little as 15- to 40-percent petroleum distillates. It can even mean products that have no petroleum content, such as turpentine.

Composition

Mineral spirits are derived from minerals: in this case, petroleum. All products labeled as mineral spirits should contain 100-percent mineral spirits, unblended and with no additives. Pure mineral spirits are a paint thinner.

Products labeled as paint thinner can refer to pure mineral spirits, blended mineral spirits, turpentine, acetone, naphtha, or any number of other products capable of thinning oil-based paint. Most often, though, paint thinner means less refined mineral spirits with 5-percent or less benzene content added for better solvency and aroma.

It is important to distinguish the class of blended and unblended mineral spirits from other classes of products capable of thinning paint. The former class, derived from petroleum, is clear, non-sticky, and relatively odor-free. The latter class can include products such as turpentine, derived entirely from pine tree oleoresins and with no petroleum content. In fact, due to turpentine's foul odor and caustic nature, mineral spirits, often called white spirits, were developed as a safer, gentler solvent.

Also, those blended and unblended mineral spirits differ vastly from solvents commonly advertised as paint strippers or paint removers. These solvents, meant to dissolve hardened paint, contain a host of chemicals such as alcohol, methanol, and xylene, to name only a few.

Odor

Both unblended mineral spirits and blended mineral spirits called paint thinners have an odor similar to camping lantern oil or kerosene. Due to the added benzene, paint thinner will have more of an odor than will pure mineral spirits. The smell is typically sweet and most users do not find it objectionable. Due to the difference in odor, pure mineral spirits tend to be better for interior use.

Generally, both straight mineral spirits and mineral spirits-related paint thinner are low in odor in comparison to the foul, chemical-like smell of other classes of paint thinners.

Safety

Pure mineral spirits and related paint thinner have no difference in terms of safety. Each product ranks the same in all safety categories of the OSHA-mandated Safety Data Sheet (SDS) for paints and solvents. When inhaled, benzene can cause drowsiness and even can render one unconscious. Long-term exposure in high quantities may adversely affect your health. For that reason, always make sure that you are working in a well-ventilated area when using mineral spirits with added benzene.

Cost Difference

Mineral spirits usually cost more than blended paint thinners. Generally, pure mineral spirits will cost about 40 to 50 percent more than mineral spirits-based paint thinners with additives.

Uses

  • Thinning oil- or alkyd-based paints while those paints are still in soluble form
  • Cleaning brushes that have wet paint on them (not dried or hardened paint)
  • Degreasing or cleaning oily equipment or tools

Should You Buy Mineral Spirits or Paint Thinner?

Both mineral spirits and paint thinners that are blended mineral spirits perform largely the same functions. Both are clean, clear, and non-sticky solvents for thinning and for cleaning oil-based paints, stains, and varnishes. Pure mineral spirits are more expensive, so it is recommended that you use them more sparingly. Since paint thinner is less expensive, it is best for large residential use or commercial use. Because pure mineral spirits have a lower odor, they are best for indoor use.