If you like working on an oil ground but don't want to deal with the time or mess of oil grounds, here's a good solution.
The following recipe will:
- Create a "higher" surface
- Keep the colors more true upon drying
- Cause less drag on your brush
- Create what I consider to be a "brighter" surface
- Will not effect the long-term adhesion of your paint
1/3 damar varnish (in solution, Winsor & Newton, Grumbacher etc.)
2/3 turpentine or Gamsol
Mix these well and keep them on hand in a well-marked jar. Apply one coat to your gessoed surface with a soft brush or disposable foam brush. It will be dry and ready to paint on in less than half an hour.
You can play with the proportions, but any more damar varnish than is indicated will make your surface frustratingly slippery. If anything try a little less varnish -