Sunday, May 6, 2012


Odorless Mineral Spirits (OMS) is a solvent that oil painters commonly substitute for gum turpentine.

Why not just use turpentine? It's a serious health hazard. Additionally, some people are, or become allergic or sensitized. See this OSHA document for details.

Solvents are used for thinning oil paint, cleaning brushes and as an ingredient of mediums. OMS can handle thinning and cleaning but may not be strong enough for some mediums.

I pulled up the Material Safety Data Sheets (MSDS) for these brands of artists's OMS:
  • Weber Turpenoid - Aliphatic Hydrocarbon 100%
  • Gamblin Gamsol -  Naptha(Petroleum), Hydrotreated heavy
  • Winsor & Newton Sansador - Distillates (Petroleum), Hydrotreated light
They are all quite similar, and even may compare to the OMS you will find in a hardware store. I spent hours Googling these solvents, trying to determine which brand might be safest and still perform.  What I did find for my research was a wealth of misinformation, a good deal of it from large artist's forums. I've come to find reliable information from these web resources:
In this case, AMIEN held the answers. Here are a couple of forum quotes that I used to based my decision:
There are significant differences that make true, highly-refined odorless mineral spirits safer alternatives to turpentine. True odorless mineral spirit has the aromatic component refined out of it – less than .005% remains. Most significantly, OMS has an evaporation rate approximately 3 – 5 times slower than turpentine – this means that during a painting session you will work around less evaporated solvent. In addition, OMS has a high flash point, and is not absorbed into healthy skin. 
. . .
The other factor we will want to consider is the health issue of solvent exposure. You'll find some art store brands to be less toxic than a typical hardware store variety... The following are Threshold Limit Values (TLV) for an 8 hour work day (according to ACGIH). Higher values are LESS toxic.

Turpentine 100ppm (including W&N distilled)
Aliphatic Hydrocarbons 100ppm (Turpenoid, Utrecht Odorless)
Iso-paraffinic Hydrocarbons 171ppm (Maimeri Odorless)
Common hardware store OMS 100-200ppm
Hydro-treated Heavy Naptha 300ppm (includes Gamsol)

Hydro-treated Heavy Naptha at 300ppm will have the minimum of aromatic solvent content and be less toxic, as the AMIEN staff suggested. The art store OMS at 200ppm may have less of the really nasty "impurities" of the common hardware store OMS like 1,2,4-tri methyl benzene at 10ppm.

. . .

If you find this interesting, I urge you to follow the links and make your own decisions. Based on my research, I will be soon using Gamsol--my Turpenoid bottle is nearly empty.


  1. Sorry for my silence of late- no reflection on anything other than my trying to stay away from technology for a bit; far too easy to spend way too much time on the computer, (esp, when you keep linking us to such interesting websites.:-) I still am plowing through Paul's "Learning to See" blog).
    I have been simplfying my art process of late, still working only in colored pencil on toned paper and sketching simply for the sake of sketching ( and the zen-like experience that comes with it ) with no pressure for a finished piece or worry about the outcome.
    I gave up on turpentine and all other solvents years ago due to headaches and what felt like a caffiene induced anxiousness that lingered for hours after being around the vapors; I now only work with the water soluable oils- not very traditional I'm afraid, but I sure feel a lot better!
    ~ gretchen

  2. I applaud your efforts to limit exposure of computer time. It sure can be a time sink. But of course, there are some great resources out there. Glad you're enjoying Paul's work; I'm learning lots from him.

    Your Zen sketching sounds intriguing. I'm on the edge of something similar with my blocks. I plan to begin sketching and painting them this evening, letting myself go with simple planes of tone.

    So far I use very little OMS--a bit for brush cleanup. I did use some for mixing down my paint for the wood blocks, not so much to thin but more to reduce glare. That worked fairly well, especially with the ivory black.