The debate continues about using acrylic paints and oils in the same painting. Most of the time, an artist will use an acrylic painting first as an underpainting, then proceed to finish the work in oils. The question is: will painting with oils over acrylics hold up over time?
Some critics of this practice point to evidence that suggests the oil layer will eventually peel away from the acrylic layer underneath. Acrylics, they say, is still relatively new to the market place and there is no long term history to back up the belief that its okay to use as a layer beneath oils. Others believe it is okay, just as long as the acrylic layer comes first. Painting acrylic over oil is a guaranteed disaster. However, the consensus is still out on whether painting oil over acrylic is advisable.
Much of the thinking goes like this: we use "acrylic gesso" as an undercoat, so why not also use acrylic paint to get us started? It dries so quickly, it allows the artist to lay down a quick drawing or underpainting and begin work with oils the same day. However, "acrylic gesso" and "acrylic paint" are not the same thing. Acrylic gesso contains additives to increase absorption and provide tooth. Acrylic paint dries to a relatively smooth surface and is not as absorbent. Is it best to stick with oils throughout the process and avoid using acrylic paint AND gesso? Some would say the best ground for an oil painting is lead white.
Staffers at Golden Paints have seen paintings with oil over acrylic layers that have lasted 20+ years without any apparent peeling or damage. However, a more conservative view that errs on the side of caution would promote using acrylic gesso and/or paint in layers as thin and matte as possible. They point out that acrylic paints, in general, are porous enough to provide adhesion with an oil layer. However, George O' Hanlon at Natural Pigments writes "I tend to err on on the conservative side. There is not enough information yet about this practice to make it a 'best practice.'"
As for my own work, I began using acrylic gesso and thinly applied acrylic paints for underpainting. Acrylics are generally cheaper than oils, and they dried so quickly it was easy to get started with oils within an hour. Having said that, it has been suggested that a layer of acrylic needs to be fully dry and free of any moisture prior to applying oils. So I was most likely painting my oil layers too quickly over acrylic. If I do it right, how much time do I really save?
I have changed my approach. I don't want to take any chances. I have switched to an oil-based gesso, like Gamblin's oil ground. I then use lead white and raw umber for underpainting and drawing. They dry quickly and I can avoid using acrylics.
