During the 1950-60’s, turpentine was the solvent for paint, varnish, oil colors and for cleaning brushes. It was also used to remove soils from equipment, hands and other oily surfaces. Turpentine is a very powerful solvent, dries quickly and is still used today for very specific uses. The problems with turpentine are many but for our use in the studio it is a generally a bio-hazardous material and must be avoided.
The next generation of common oil color solvents is mineral spirits which is the solvent for house paints as well. Mineral spirits are one of the distillates of crude oil. They are not as aggressive as turpentine and dry slower. Mineral spirits are still irritating and require well ventilated work spaces. It does clean brushes but requires the precautions mentioned.
The next level of improvement is the further refinement of mineral spirits which is odorless mineral spirits (OMS). The brand names of a few are Gamsol by Gamblin Artist’s Colors and another is Turpenoid by Martin F. Weber Co. These are less toxic but still require precautions.
Turpenoid Natural, not to be confused with Turpenoid OMS, is a product which does contain a citrus ingredient and is non-toxic, non-combustible, fragrant, water soluble, and a very strong oil paint solvent. Its other contents are not given. I use it for cleaning brushes but I’m not yet convinced of its chemistry to use it for thinning oil colors.
For cleaning brushes that I have just used, a paper towel wipes off the excess colors from the bristles. Then it goes into a small jar with about a half an inch of Turpenoid Natural and work the bristles around the bottom until they look clean. And then another wipe of the paper towel.
So far this is the same procedure as any solvent. The big difference is now that the brushes go to the slop-sink where tepid water rinse will wash away the remaining pigment and solvent against the palm of the hand until the water runs clean. A wipe with a paper towel the the bristles are really clean, up into the heel and conditioned for the next use. There is no need for washing the brush with the conventional soap lathering and rinsing.
I have not tested the following recommendation from the Weber Co. as my brushes are rather clean. Their statement is that Turpenoid Natural can clean brushes with dried paint in the heel. This works for oil, alkyd and acrylic paints they say.
UPDATE 12-19-2013 *******************
Using a 2 inch gesso brush to apply a polly-varnish to repair a small area of wood flooring, the brush was cleaned with OMS, washed in the utility sink with soap and water and let the brush dry for a few days. When picking it up to put into my jars, the bristles were all stiff. The untested claim of Weber Co. on the Turpenoid Natural was to be tested. Using a small jar with enough Turpenoid to cover all of the bristles.
Not remembering of the experiment sitting in the corner table, it came to my attention this morning after sitting for two days. Pushing down on the brush the bristles all bent easily. Off to the slop-sink with the usual washing sequence gave a brush with an almost new character. Their claim did work.
Here is my 25 year collection of clean brushes of various types and sizes. They range from foam, very fine scripts, swords, Winsor & Newton Series 7 sable, watercolor brushes, Langnickle Royal Sable and Signet bristles. There are also an assortment of utility bristle brushes, large and small. You may notice that the tips of some brushes are stained by pigments. This discoloration cannot be removed and it does not transfer to new colors. More on brush types in a following post.