when trying to oil out dull areas, glaze or put a varnish over my paintings in some areas the medium, varnish or thinned paint just beads up. It is difficult to cover with anything except straight paint. I use Williamsburg and Winsdor and Newton paints lightly thinned with linseed oil on a lead grounded high quality linen canvas. I’ve been told to use toluene in the varnish or medium.
Beading is a really common behavior in oil paints where layered techniques are concerned. Overcoming this behavior is one of the key functions of varnish in a painting medium, to add tack. Traditional remedies included rubbing a clove of garlic on the paint surface.One of our paint chemists a while ago suggested wiping the painting with household ammonia to reduce gloss and render the surface more receptive prior to glazing.* I have also read that some artists use odorless mineral spirits for the same purpose, or alternately mechanically abrade with extremely fine steel wool. I wouldn’t consider toluene a safe enough solvent for use in the studio, not as a component of medium.
*On the advice of our conservation scientist Moderators, I am omitting this