Mineral spirits are a type of solvent typically used for cleaning tools and machinery that tend to build up grease and grime. They will also thin oil-based materials, such as paints and varnishes. There are several advantages to using mineral spirits over traditional thinner in the case of paint, though the differences are fairly subtle. Paint thinner is mineral spirits in a less refined form, containing other types of solvents. “Washed” mineral spirits generally cost a good deal more but are preferable depending on their use.
1. The Smell
Paint thinner is noxious stuff. The vapors are enough to lay you out if you don’t take proper precautions. You need to take care not to inhale too much, as it can cause many harmful side effects, including death. Because paint thinner contains various solvents, this gives it more extreme noxiousness. "Washed" mineral spirits have a much lower odor factor and are much easier to use for many people because of this.
It is very important to always use solvents in a well-ventilated room, even though mineral spirits are less potent smelling. If you begin to feel light-headed or develop a headache, immediately remove yourself from the room and get some fresh air.
2. The Cost
Usually, paint thinner is cheaper to purchase by a pretty good amount. Mineral spirits can be up to double the cost because it receives more thorough refinement. This cleaning of the material also is what makes it less noxious to use. The bottom line is that it takes more work to produce mineral spirits than paint thinner, and you get what you pay for.
Mineral spirits tend to be more effective in terms of solvent properties and cleaning capabilities. This is again due to the fact that it is a much more purified form than paint thinner. Many artists prefer mineral spirits due to the substance's ability to quickly clean any painting utensil they might use. It is also a more effective solvent and is the preferable thinning fluid. Because it is more effective overall, that can make up for the difference in cost compared to paint thinner.
Use a non-reactive container to clean brushes in (glass or stainless steel), and always store leftover solvent in a tightly closed container. Do not pour used product down a drain or dump it out onto the ground. Seek out a reputable recycling center to dispose of waste.
These two products have the same basic function, but obviously, there are a couple of differences that you should take into consideration when deciding what to use. Ultimately, the choice comes down to personal preference based on the purpose you intend to use the solvent for.
Pam Estabrooke of ProTect Painters contributed to this article.