Oil Primed Canvas on Panel
That depends on the type of canvas surface with which you are working.
The panel I am using for this demonstration is 20 x 24, 1/4-inch composite panel with oil primed Raphael linen canvas mounted to it.
The two most important words in that paragraph are “oil” and “primed”. The canvas was originally primed and prepared by the manufacturer with an oil based primer. Whatever goes on top of that has to also be oil. In this case, oil paint.
The second purpose of surface preparation is sealing whatever is left of the old painting so it doesn’t reappear like an unwanted ghost in the new painting.
With this particular panel, there isn’t much chance of that. There isn’t much of the old painting left. Just a few flecks of color here and there and mostly in the area that used to be sky. I could almost have painted over it just like it was.
Prepping took place in a couple of steps using M. Graham Oils Alkyd Formulation Titanium White. This is also known as ‘rapid dry white’, but that’s not the reason I chose it. I chose this formulation because the alkyd in the formulation has better adhesive qualities than straight walnut oil. Both would do fine for this purpose, but I prefer to err on the side of caution when prepping surfaces.
The first paint was applied with a rag and put on very thinly. The remaining color was muted, but not covered up. That was all right. What I wanted was a layer of paint totally devoid of brush strokes.
The next layer followed after the first layer was completely dry. A minimum of two weeks, but as long as six to eight weeks. This layer must be completely dry or you run the risk of peeling paint later on. The extra time spent here is well worth having to redo a nearly finished painting later on.
The second layer was applied with a palette knife to spread the paint across the surface. I then brushed it out with a large bristle brush. The first time across, the brush strokes were horizontal. I followed that by brushing the paint out even further, but on a diagonal. Working in two directions creates a more even paint layer and reduces the prominence of the brush strokes.
This application covered almost all of the remaining paint. Only faint ‘ghosts’ of color remained. The canvas was then set aside to dry again.
You can apply as many layers as you wish. Again, I stress the importance of letting the panel dry completely. It’s not uncommon for panels being recycled to sit around for a year or more before I use them.
If you don’t want to wait that long, you can test the panel with a razor blade. Scrape the blade lightly across the surface in any direction. If paint rolls along the blade, it’s not ready to work on. If it powders off the panel, it is ready enough to work on. Ideally, you should get little or no scrapings of any kind, but if you do, dust is what you want to see.
Give the panel a light sanding once it passes the test (if you want a smoother surface) and it’s ready to go.