I see recomendations for water miscible oil paint for ease of clean up and not using solvents.
Can you please comment on them from the viewpoint of longevity?
Ron Francis
Can I assume that a painting done with water miscible paint is more sensitive to water than one done with linseed? (Or poppy, walnut, safflower etc?)
Also, could this make it more hygroscopic and therefore more susceptible to cracking caused by changes atmospheric moisture?
They appear to remain sensitive to water even after dry for a substantial time. However, this could be said of other popular paint mediums as well. I also believe that the additives used to make them initially water miscible can migrate. Again, this is not unique to Water miscible oil paints.
Water miscible oil paints tend to be less fully pigmented than the highest quality ranges and are usually sold as entry-level paints. Therefore, it is probably unfair to compare them to superior oil paints lines that contain no fillers and only the most minimal stabilizers.
For now these assumptions are probably good ones. However more time is still needed (and far more research) in order to confirm these theories regarding WM oil films.
Some of the stabilizers/fillers used in this category of oils are borrowed from the food and cosmetics industries (as revealed in patent applications). I’ve been curious for a while about the long-term performance of these additives, which are different from stearates.
Artists’ materials manufacturers use several methods to make water-miscible or water-reducible oil paints. Grumbacher patented one process in 1994. The technique used in this patent involves preparing a gel base consisting of castor wax and an emulsifier (polyoxyethylene sorbitol hexaoleate ester), later mixed with an amine soap. While portions of the emulsifier will volatilize over time, most of the soap and emulsifier remain in the paint film. Based on these ingredients, this likely would make these paint films sensitive to water. More research should be done to determine how this ultimately affects the properties of the paint film.
For more information, please see the following:
US Patent 5312482A, Chambers, et al, Water Reducible Artists’ Oil Paints Compositions, May 17, 1994: https://patents.google.com/patent/US5312482A/en
Brynn N. Sundberg, Physicochemical Characterization of Winsor & Newton’s Artisan Water-mixable Oil Paints, Thesis for M.S. in Chemistry, Advisor: Dr. Anthony F. Lagalante.