I have a solution to prevent dust from getting on a freshly varnished painting.
I was considering using spray varnish but I ended up going with a known tried and true Gamar gloss. I did change up and used a nice 1 1/2” Master trim brush of fine synthetic material. It doesn’t lose any brush hairs and doesn’t leave any brush marks.
But the game changer is this cardboard box that lets me close the top and prevent dust from getting in the painting.