From Art Geek:
I may have stumbled across the solution to a painting problem which has vexed me for a long time. It involves the rules for mixing different kinds of media in the same work.
As most painters know, oil and acrylics are fundamentally different beasts with different properties. Oils dry slowly and are therefore matchless for smooth, blended transitions of rich colors; they also tend to yellow slightly, more so if a lot of medium is used. Acrylics dry quickly, never yellow, and, since they stay strong and flexible, can be layered and textured in ways that would be detrimental to the longevity of one’s paintings if painted in oil. Unlike oil, acrylics can be painted over “unprimed” supports such as wood or canvas. Acrylics also have more 'tooth’ and are wonderful for drawing, collage and photo transfers. But the time usually comes in a painting when the longer “open time” of oils is vital, for blending layers and making richer, more subtle paint surfaces.
The biggest problem with traditional oils is that they require turpentine or other organic solvents to make washes and glazes; these solvents are hazardous and even the mildest of them are best avoided or minimized by folks (like me) with some level of sensitivity to their vapors. Water-soluble oils such as the excellent “Holbein Duo Aqua” colors reduce or eliminate the need for solvents and have kept me painting in oils for the past few years. The problem is that it is a major no-no to paint acrylics over oils. This is because the experts insist that adhesion of the porous, flexible acrylic film is not reliable on top of the waxy, smooth surface of oil paint.
As a result, I often do some sort of acrylic underpainting when I want to add texture, do extensive drawing, or do an image transfer. My dilemma occurs when, partway though a painting, I want to add more texture, more photo transfers, or do more drawing. One solution I have played with recently is the use of gouache in underpaintings. Gouache dries quickly like acrylic, is water-soluble, and allows for subtle color transitions; but I have my doubts about its suitability as a long-term permanent underpainting (it dries water-soluble, after all).
Enter Golden’s ’Open Acrylics’, which I stumbled across the last time I made it to Dick Blick to get art supplies. This is a new paint formulation which dries much more slowly than ordinary acrylics, yet is fully compatible with acrylics. This means that one can think in terms of drawing or photo transfers, then get more “painterly” (blended colors), then go back to drawing or add more texture or photo images. I have just started playing with these paints, but so far they seem pretty promising! They don’t show the rich, buttery handling of oils, but they do stay “open” quite a long time and so far seem to combine well with the other acrylics and acrylic mediums I already have. I still expect to use the water soluble oils for the later stages of many paintings, but in the mean time I’m excited to have ways of staying in acrylics longer.
Now if only I could finish the batch of paintings I’m working on.