"Is it okay to paint on unprimed, raw canvas with acrylic, or do you run the risk of the canvas eventually rotting, as can happen with oil paints?"-- A.N.
To get a definitive answer to this question, I asked the Technical Support team at Golden Artist Colors. Golden is an American company that products quality artist's materials; they not only do a lot of research on the acrylic products they produce, but also provide detailed information sheets on their website. This is the answer I received from Technical Support team member Sarah Sands.
"You can definitely paint with acrylics on unprimed canvas without the same detrimental effects of oil paints. However, in doing so, there are a few things an artist might still want to consider.
"While acrylics will not cause canvas or linen to deteriorate, it is important to realize all fabrics made from natural fibers will age and become more fragile with time. They also remain vulnerable, of course, to mold and mildew.
"So, while you can paint directly on canvas with acrylics, the future condition of the piece will very much be tied to the support; what happens to the one happens to the other. How critical this issue becomes will depend largely on how the artist paints. For example, stains and washes are obviously more bound to the fate of the fabric than applying substantial layers of paint would be.
"Artists wanting the look of raw canvas while avoiding these problems could try using our Fluid or Regular Matte Medium as a form of clear gesso, or else try our Absorbent Ground which comes in a fairly convincing canvas color. Obviously, though, either of these solutions will also affect how the paint is taken, so it's not ideal for many situations.
"Lastly, even if painting on raw canvas, the artist will be confronted with how to protect the final surface since dirt and dust will easily find their way into the fabric and cause major concerns in terms of cleaning and future conservation. To address these last concerns, and to help consolidate the piece in general, an artist should consider use of an isolation coat and final varnish."
-- Sarah Sands, Technical Support team, Golden Artist Colors, Inc.