Q. I’ve always used turpentine for cleaning brushes, but a fellow painter told me he uses vegetable oil. He didn’t mention how he disposes of it or how he gets rid of the mineral spirits for the medium. How do you recommend disposing of the vegetable oil and the mineral spirit sediment? Is it safer to dispose of than turpentine?
A. Many oil painters, choosing to avoid turpentine and related solvents as ways of cleaning paint from brushes, have turned to options that are more healthful and better for the environment. One of the ways to avoid using solvents is to substitute a vegetable oil for turpentine. Use a drying oil—such as safflower oil, poppyseed oil or walnut oil—so any residue lingering in the brush will be compatible with existing oil paints. Many painters extol the virtues of mineral oil as a brush cleaner, but it’s a nondrying oil that could contaminate paint and compromise film formation. Since drying oils can perform brush-cleaning tasks well, it would be wise to select an oil that won’t harm a painting.
Make sure the drying oil you use is low in viscosity. Thin oils work well as a brush cleaner because they allow pigment particles to settle out of suspension and form a layer in the bottom of the container used to clean brushes. One of the best containers for this method of brush cleaning is a solvent can that has an inner sleeve with holes in the bottom. This inner container is suspended above the bottom of the can so brushes may be cleaned while pigment particles settle to the lower portion of the container.
Waste disposal is determined by local ordinances. State and county laws govern how solvents and paint-related waste products are handled. Many localities have special programs to collect waste paint or leftover paint from home projects. You should consider your brush-cleaning oil as a form of oil paint and act in accordance with your local disposal center’s directives.
Take note of the pigments you use, since some metal-based colors may have special dumping restrictions. Products containing lead may have special guidelines, too. Some jurisdictions require paint waste to be disposed of in solid form. This is where using a drying oil becomes valuable. Under no circumstances should you pour these materials down your drain or bury them in your backyard.