Ask the Experts: Technical Questions Answered for Artists
by Bradley Lance Moore
Alcohol as Antifreeze
Q: I’ve heard that adding alcohol to watercolor will keep it from freezing in very cold temperatures when an artist is painting en plein air. What effect does the alcohol have on the archival quality of the subsequent painting?
A. Alcohol is an effective antifreeze for watercolor, and if you use the alcohol judiciously, your work should remain archival. Both isopropanol and ethanol rubbing alcohol may be used, although there are differences to consider. Pure isopropanol freezes at 127 degrees below zero Fahrenheit, whereas ethanol freezes at 173 degrees below zero, so a smaller amount of the latter could be used. Isopropanol doesn’t mix as readily with water, which can create “interesting” textural effects.
Ethanol is the active ingredient in alcoholic beverages. Artists who add this type of alcohol should use a clear liquid like grain alcohol, vodka or gin. Liquor that’s 64 proof freezes at 10 below zero, and 84-proof liquor freezes at 30 below zero. Artists sometimes add up to 20 percent of 84-proof liquor to their watercolors.
Not all pigments behave alike when in contact with alcohol. Consequently, if a color is composed of two pigments, one of those pigments may bleed into the alcohol while the other may not, resulting in a separation effect. Also, you may notice difficulty in lifting colors whose dyes are more soluble in alcohol because the alcohol enhances those dyes’ staining properties.
Some watercolorists use alcohol with tube colors but not with pan colors because the alcohol seems to dry out the gum arabic binder in the pans too much, resulting in a powdery paint that won’t sufficiently bind to a surface. Alcohol also can have a detrimental effect on natural-hair brushes because, while alcohol solutions may not freeze in the brushes, the alcohol can strip natural oils from the hairs, causing embrittlement and breakage over time. Also, depending on the adhesive used in the ferrule, alcohol can soften the bond, dislodging the hairs.
In addition to lowering the freezing point of watercolors, alcohol can act as a wetting agent and, in humid conditions, as a drier. You may also add up to 10 percent alcohol to your paints as a preservative. Finally, if alcohol isn’t for you, adding a touch of glycerin and ox gall can also help keep your colors flowing in freezing conditions.
Find more “Ask the Experts” Q&As here! Bradley Lance Moore has both a master of science degree in painting conservation and a master of fine arts degree in painting. He teaches art history and studio art at the Maryland Institute College of Art in Baltimore and exhibits his artwork internationally. Visit his website at www.blancemoore.com.
MORE RESOURCES FOR ARTISTS