The Dose Makes the Poison
Are water-miscible oil paints safe? Good news.
Water-miscible oil paints are the latest "hot thing" now. Some artists seem to be moving away from traditional oils because of health concerns around mineral spirits. Safer practices include using solvent-free products like Gamblin's solvent-free mediums, cleaning brushes with vegetable oil (plus soap and water)—or switching to water-miscible oil paints.1
But are water-miscible oil paints any safer? Sure, you don't need to use a toxic solvent with them, but what about the paints themselves? Read on.
First, let's see how these paints work. We all know the adage, "Oil and water don't mix." These new paints—actually, they've been around since the 90s but only recently have become more popular—have a surfactant or dispersant added that helps. Think of how soap can cut grease in your frying pan.
To find out more, I asked Michael Skalka, who writes the very informative Syntax of Color blog and who is the retired Conservation Administrator for the National Gallery of Art in Washington DC and chairman of the subcommittee of the American Society of Testing and Materials (ASTM) D01.57, Artists' Materials, about them. A plein air painter who uses water-miscible paints, he replied:
Water-miscible oils have a surfactant added to the oil that lets water dilute the paint. While we can say that all ‘soaps" are composed using a surfactant, in the case of oils used for water-miscible paints, the detergent or sudsy factor is not present as it is in soaps. The technology of water-miscible oils has been used extensively in farming. Oil sprays with water-miscible oils allow the chemicals intended to stay on a plant for a longer bit of time then if a water-based chemical were applied. Rain eventually breaks down the oil over time so it washes away but not too quickly.
Are these added chemicals safe? Well, it depends. I looked up the Manufacturer's Safety Data Sheet (MSDS) for Grumbacher Max Water Mixable Oils. The magic ingredient is a chemical called amino-2 methyl propanol (AMP.) According to the MSDS, the product:
Causes serious eye irritiation. Harmful to aquatic life with long lasting effects. May cause an allergic skin reaction. Suspected of causing cancer. Very toxic to aquatic life. Very toxic to aquatic life with long lasting effects.
(I like the way the statement mentions aquatic life three times for emphasis.)
The National Oceanic and Atmospheric Administration, agrees that dispersants and surfactants like AMP are toxic to aquatic life. Other water-miscible oil paints contain similar ingredients.
But does this mean we shouldn't use water-miscible paints? The 16th century Swiss physician and alchemist, Paracelsus, is said to have written, "The dose makes the poison," meaning that a large enough dose of anything will be toxic. Many things we use safely today have tiny amounts of chemicals that, in larger amounts, are toxic. Even acrylic paint, long considered a safe substitute for oil paints, contains formaldehyde—a respiratory irritant and carcinogen—and other interesting compounds. (Here's a link to the MSDS for Golden Artist Colors’ high flow acrylics.)
As artists, we need to know our materials—and to use them with mindfulness and care.
Personally, I have tried a number of brands of water-miscible paints, and I dislike the texture and handling. (And contrary to what some people think, you can't thin them successfully with water; you still need a medium.) They seem to lack a "butteriness" that traditional oils offer.
As for avoiding the toxicity of mineral spirits, you don't need mineral spirits to paint with traditional oils, or even to clean your brushes. Gamblin makes a line of solvent-free mediums to paint with, and as for cleaning, you can use linseed oil or similar to get most of the oil out of the brushes before taking them to the sink for a proper washing with soap. (For this, I like Murphy's Oil Soap, which contains a bit of potassium hydroxide, a type of lye. So it goes.)
Also sometimes called water-soluble, water-mixable or water-reducible oil paints.