MITRA Forum Question Details

Yes, it's certainly possible to achieve durable results using oil colors with a minimum effective amount​ of drying oil as a medium. Since you'll be using manual force to deposit paint, oil with lower viscosity like walnut or raw linseed would work better than polymerized oils like stand and thickened. A "thirsty" or "slow" ground like acrylic dispersion primer ('gesso') will cause strokes to break and drag, so you may want to reserve some cheaper or worn brushes to rough in the frottis when working in oil over acrylic. You may wear out some tufts at first until you get used to the more viscous paint; generously loading the brush helps.

A "fast" ground like oil or alkyd will facilitate smoother brush movement in the first layer. An acrylic ground can be made less absorbent by rubbing in a very small amount of oil (again, the bare minimum effective amount).

More neutral-colored oils like safflower and poppy are generally slower drying than linseed oil. You can support faster drying without using catalytic siccatives like Japan Drier by selecting pigments that are strong driers, like raw and burnt umber, which can be added in tiny amounts to blacks and dark neutrals.

In addition to pigment selction, keeping the painting in inirect light, in a warm environment, and with good air flow (not direct sunlight, unless this is only for a very limited time like a few hours, and without the use of strong heaters or fans) will promote a good drying rate. Your choice of oil should be directed by the handling properties and effects that you are trying to achieve. Smooth, long, or easily blended strokes require a less viscous oil or a thin couch of oil to paint into. Broken, dragged effects may require less oil or a stickier, viscous variety. Also, as Matthew mentioned, the type of ground will play a major role in these handling properties as well.

Oil paint will adhere to a dry layer of acrylic medium, but it might be a good idea to first evaluate different brands of acrylic primer to see if one yields the results you want. Some are more absorbent than others.

It should be fine as long as you avoid applying so much acrylic medium that it becomes overly slick and glassy. ​That could cause adhesion problems and possible delamination.