Last week we explored the properties and uses of denatured alcohol, an important solvent we use to clean surfaces and equipment for industrial and commercial painting. We also rely on mineral spirits for reducing paints and cleaning application tools after use. Although it has similar uses to those of denatured alcohol, mineral spirits have different physicochemical properties.
Mineral spirits, also known as “white spirit,” are petroleum-sourced mixtures of medium-chain aliphatic hydrocarbons ranging from 6 to 12 carbon atoms, but having a predominance of chains with 10 or more carbons as well as hexane (C6H14). Some mineral spirits also contain aromatic hydrocarbons like benzene. However, others, like Sherwin Williams R1K4 Mineral Spirits, are 100 percent aliphatic. The R1K4 product has a weight, volatile organic compound content and coating density of 6.42 pounds per gallon. The product’s flash point is 105°F and its specific gravity is 0.77. Other fun facts: R1K4 boils between 300°F and 395°F, is heavier than air and evaporates slower than does ether.
Mineral spirits are synthesized by the fractional distillation of petroleum. The degree of processing can result in three different types of mineral spirits:
- The distillate has undergone hydro-desulfurization, removing most of the naturally occurring sulfur products.
- Further distillation removes the aromatic compounds. Almost all mineral spirits sold in the U.S are Type II.
- Additional hydrogenation modifies the chemical makeup for specialized applications.
The removal of aromatics in Type II mineral spirits considerably reduces unpleasant odors. In addition to type, mineral spirits are categorized by three grades:
- High flashpoint/low volatility
- Medium flashpoint/medium volatility
- Low flashpoint/high volatility
R1K4 is a Type II Grade 2 mineral spirits. It is non-polar, non-photochemically reactive and HAPs (hazardous air pollutants) compliant.
Uses for Mineral Spirits
Aliphatic solvents are slow-evaporating, fairly weak solvents and therefore suitable for reducing alkyd enamels and cleaning alkyd paints from brushes and other tools/equipment. Mineral spirits can reduce both medium- and long-chained alkyds, such as the Sherwin Williams enamel paints we discussed a couple of weeks ago. As a solvent and cleaner, most folks prefer mineral spirits to turpentine, which is stronger (it can dissolve non-alkyd resins), but also thicker and stinkier. The most important uses of mineral spirits include:
- Paint thinner/reducer
- Paint cleaner
- Thread-cutting lubricant
- Cleaning silk screening equipment after use
- Ink thinner
- Fluid component of compasses and gauges
- Regripping golf clubs
- Fuel and fuel additive
- Diamond-turning machine cutting fluid
Mineral spirits are an irritant. It’s best not to breathe in the vapors or allow the spirits to remain in contact with your skin. Repeated skin exposure can lead to contact dermatitis, and prolonged contact can burn the skin. Certainly, you don’t want to ingest it. Overexposure can lead to depression of the central nervous system and, in high concentrations, will cause you to pass out and may cause permanent brain damage.
R1K4 lists the following precautions:
- Use with adequate ventilation
- Avoid contact with skin and eyes, wear gloves and safety glasses with unperforated sideshields, and wash hands after use
- Avoid breathing in — local exhaust is preferred, although in tight spaces you should use an approved respirator
- Misusing mineral spirits by purposely breathing in vapors can kill you