- Buy an acrylic-primed, stretched canvas and some oil primer. Avoid the ones made poorly with really cheap materials.
- Clean the canvas with denatured alcohol and let it dry.
- Spread primer onto the canvas with a knife. Make the layer thin. You can dilute the primer slightly with solvent if desired.
- Use your fingers to rub the primer into the weave of the canvas. Keep rubbing until you have a very smooth, very thin layer of primer.
- If it’s a leaded primer, then wear gloves and take other precautions as needed to insure that you don’t ingest any.
- Place the canvas facing inward toward a wall to limit the amount of dust that will fall onto it before it dries.
- Allow the primer to cure for at least several weeks.
Is this as good, archivally, as stretching and priming the canvas from scratch? No, it is not. Is it a really bad idea? I don’t see why it would be any worse than painting straight onto acrylic-primed canvas.
It makes a very smooth, nonabsorbent, lovely surface to paint on.