After completing a small-format painting for a friend, and that I was afraid might be exposed to a problematic atmosphere, I decided to seal the surface with varnish to protect it.
The spray varnish (Krylon Gallery Series UV Archival varnish) I had used successfully on canvas did not work so well on paper, leaving white flecks where I had expected a clear, even finish.
Rechecking the canvas I had sprayed previously, to see if I had overlooked a similar problem with that, I found white filaments, about 1/32” long, scattered across the surface of the canvas. But were they from the spray or from some other source? They did not look like the flecks left on the paper, and I was able to brush them off with no difficulty, which I was not able to do with the flecks on the paper surface, so I judged that they were not from the spray. More likely they were some form of dust, though I couldn’t figure out what would have produced the regular, elongated shape of those flecks. It continues to baffle me. But that issue is beyond the realm of this blog.
Although I was fairly certain that the new painting (the one on paper) had been completely dry, I supposed that it was possible that it had not been and that, as the varnish hit it, some of the color lifted off. But I couldn’t be sure. Or perhaps I had applied my second coat too soon after the initial misting. Whatever the cause, the damage was done.
I allowed the varnish to dry completely on the paper before attempting to retouch that painting by applying a top coat. Would it adhere? Or would the varnish reject it? I could find out only by trying.
Once the varnish had dried, I was able to apply a top coat of paint. Despite my fears, it did adhere, and it did improve the appearance of the painting. I was also able to tweak a few areas that I had overlooked previously. However, I did not feel that it brought the image quality back to what it had been before it was sprayed (see below). And I did not attempt to reapply the protective varnish over the final layer of paint.
In the future, I won’t be varnishing any more paintings on paper unless there’s an overriding reason to do so.