Varnish is a sore subject. I’ve nearly spoiled some of my own paintings with poor varnish, and I’ve had so-called ‘professionals’ ruin paintings (one frame shop owner in Trenton, NJ left brush hairs in the varnish coat then obliterated the painting’s surface trying to get them off—grrr).
Any artist that draws with smudge-able material, such as charcoal or pastel, has used spray varnish as an intermediate coat, and final protective cover. But not all spray varnishes are equal, as I recently discovered to my dismay.
For drawings, my workhorse is Krylon’s acrylic-based Workable Fixatif. Krylon has recently added a high-end line which they rate compatible with oil paint, but I haven’t used it. Krylon has several types of varnish, so check their literature to ensure a particular product is compatible with your medium.
The other day I finished a small self-portrait on canvas board. The piece started as gouache painting then I worked it over with pastels. I am always open to new products so I decided to use a damar-based spray from Utrecht as a final protective coat.
Mistake.
The varnish obliterated the pastel work. Disheartened, I almost abandoned the piece, but worked it over again in an attempt to revive it–like reviving a drowning swimmer. I infused some faint life into it but the underlying dammar continued its unwholesome influence and darkened the new work too. As a final coat, I used the Krylon.
TIP: test spray varnish before using it.