Wednesday, December 16, 2009
The Chemistry of Oil Painting
Above: "October Marsh from Sea Cloud Plantation" 14x18 Oil
You know the pigments used in most paints are basically the same. Often the quality of oil paints involves the concentration of the pigment or even the method of mixing the paint – what we call the binder.
With oils the binder is called a siccative – a drying oil – that hardens slowly and forms a slight film on the surface that stabilizes and hardens. When the paint (often mixed with linseed oil) is exposed to the atmosphere it “oxidizes” into a dry solid unlike watercolors which dry by evaporation. With oil paint, the drying time can take weeks or even months depending on the thickness of the paint that has been applied to the work of art.
• Tip: So if you plan on glazing or varnishing your finished oil painting, wait until it is totally dry. This could take a long time. Please patient, if you varnish a painting that isn’t completely dry the colors will bleed or “spider” with the varnish.
Linseed oil comes from flaxseed – yes the same flax that is often taken as a dietary supplement – but with certain additives that change the drying time and the way it films over or glosses over and hardens. There are other oil options such as safflower oil and I have seen walnut oil in oil paints before too. Be careful when you buy your oil paints because some of these alternative oils can yellow as they get older. I know that there are different grades and prices of oil colors, but often times we get what we pay for.
The dirty little thing about working with oils is that when it comes to the cleanup of your brushes, pallet, pallet knife and your hands is that you need an organic solvent such as turpentine or mineral spirits to really do the job. Some of my fellow artists use thick dish-washing detergent or baby wipes for cleaning their hands because they want to avoid soaking up the solvents through the skin. And if you want to be a green artist or environmentally friendly, you should never dispose of these solvents down the drain. They should be collected and taken to your county’s waste disposal site. They have proper places for such solvents and chemicals – yes even here in Edgefield! Happy Holiday Painting!
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