This weekend I received a response from my blog post on brush cleaning that read: “Of course there is the option of not using paints/painting bases based on toxins to begin with.”
All paints have two essential parts: pigments and binders. Historically, binders for paints were egg, wax, honey, or bitumen, with the occasional organic oil thrown in where it could be found . From the 16th century until the modern era, the binder of choice has been oil.
Traditional oil painting requires oil that hardens into an impermeable layer. These oils are called siccative, and the most common of them are walnut, poppy, hempseed, pine nut, castor, and linseed oils. Beeswax, bladderpod, ironweed, calendula and euphorbia oils are sometimes introduced to control drying time and reduce cracking, They’re all plant-based and harmless.
Watercolor paints are bound with gum arabic, made from the sap of various species of acacia tree. Gum arabic is easily diluted with water, and when the water evaporates, the gum binds the pigment to the paper. Gum arabic, like linseed oil, is highly edible.
The binder in acrylic paints is basically the plastic material we call acrylic safety glass, marketed under names like Plexiglas or Lucite. It is Poly(methyl methacrylate) (PMMA) suspended in water with an additive that allows the hydrophobic material to bind to water. Plexiglas isn’t particularly harmful, but I wouldn’t want to eat it, either.
What makes all paints harmful to ingest are not the binders, but the pigments. The most dangerous of these—lead, mercury, antimony, arsenic—have been removed from painters’ palettes, but some toxicity remains, particularly with the cadmiums. The risk to the painter is very low; the risk to the people who mill these pigments is greater.