MITRA Forum Question Details

There are health risks associated with exposure to Pure Gum Spirits of Turpentine, including respiratory problems and allergy-like sensitivity. Many experienced painters with a long history of turpentine use have migrated to clean Odorless Mineral Spirits. This type of solvent is not completely without risk, but OMS does not induce materials sensitivity. OMS also evaporates at a slower rate than turpentine, so the buildup of vapor is not as rapid. Even high quality art supply brands of OMS are very economical. Of course, this is still not solvent-free painting. Also, the paint doesn't behave quite the same with OMS compared to turpentine.

Damar varnish also contains turpentine, so you may want to consider replacing that component of the medium with walnut alkyd medium or solvent-free alkyd gel. These do cost more than damar (especially homemade varnish) but they do offer very nice handling and drying properties without hydrocarbon solvents.

Another reason to consider replacing damar in your studio is that a paint film containing significant amounts of damar can remain soluble for a long time, making cleaning more problematic. Since you mention that you use large volumes of medium, solubility and other drawbacks of damar (e.g. darkening, embrittlement) may be a concern.

The vegetable oil components of your medium don't generally present any particular health risk. Linseed, stand, safflower, poppy and walnut oil are all free of hazardous vapors, though some do find the smell of linseed oil unpleasant. All drying oils (including cooking oils) can spontaneously combust from buildup of heat from oxidation, when oil-soaked rags are left balled up. Rags can be left flat to dry before disposal, or immersed in water in a lidded metal can.

Finally, when solvents are present in the studio, adequate ventilation is essential- there's no substitute. Make sure air is moved and replaced, not just moved around with a fan.

Hi

The medium you describe was used by many, many painters in the 20th century and is identical to the medium Ralph Mayer suggested for glazing in oils (although his recommendation contained cobalt drier as well). Today this medium is not considered as benevolent as it was in the past. The large percentage of soft dammar resin can contribute to a paint film that is sensitive to the solvents used to remove degraded varnish in the future. It also contributes a degree of brittleness to the paint. Stable paintings can be made using such a medium but it would need to be added in very small proportions as compared to the oil paint. In practice, this is unlikely and it is best to avoid mediums that contain soft resins. Finally, the dammar is the reason why you have required turpentine rather than a less noxious solvent like a highly refined zero-aromatic odorless mineral spirits. Dammar is not soluble in these solvents and requires either turpentine or a mixture with a high proportion of aromatic hydrocarbons.

There are some other alternative solvents but they tend to smell just as noxious during longer painting sessions. Some of the claims of lower toxicity for some of these may actually simply be the result that they have not been tested as extensively as the more common diluents.

So, what you need is an oil medium that does not require turpentine (or aromatic hydrocarbons) or soft resin.  Stand oil diluted with a solvent is perfectly fine in terms of stability. It may be less desirable in terms of paint handling. It really depends on what you are after. I have found that this mixture really levels paint strokes and can contribute a greasy effect rather quickly. It is sticky without having the “feel” that your old medium had due to the resin. Linseed oil and solvent is workable as well although its “feel” is also very different from what you are used to.

I personally have not liked the handling of gelled alkyd mediums but others really love them. I have found that the fluid alkyd mediums more closely resemble the older mediums like the one you describe. You may want to thin them with additional OMS if you use larger amounts of medium as you suggest. You could even use one of these as a component of a three-part medium by substituting the alkyd for the damar and OMS for the turpentine. Finally, have you tried using any of the newer solvent free oil mediums? A Google search should yield a number of these offered by different manufacturers.

Sorry if this is a less than satisfactory answer. Perhaps others here have a different or additional take on this issue.

​Ha

Matthew, you posted while I was editing my post. Anyway, multiple voices are always better. Thanks for the commentary on the health issues. I had completely missed that in my response.

Brian, We've been tripping over each other lately! I'm glad if I added something useful.