Can acrylic color be safely added to Polyurethane or Polymer Varnish to make a glazing varnish?
You can mix paint with both Polyurethane and Polymer Varnish, but essentially, the Polyurethane mixture becomes more porous proportionately with added acrylic. In Polymer Varnish, mixtures may become alkaline sensitive like neat varnish is. We've never tested the level of regular acrylic to Polymer Varnish you would have to achieve, but if you were using it as a glaze mix, then we'd guess it's going to remove as easy as the varnish does. However, if you HAD to do this or HAVE done this, then the MSA Varnish or other solvent based ones should be used over it and the combination of products noted on the back panel or stretcher bar.

What if I need a semi-gloss sheen? Are varnishes with varying sheens intermixable?
The three sheens of GOLDEN Varnish, gloss, satin, and matte can be easily blended to create a custom varnish. We suggest mixing the varnishes together and THEN thinning with the appropriate solvent. A good way to test the sheen is to make an acrylic panel with several dark paints on it and brush some of the varnish out. After it dries you can compare it to unvarnished areas and other mixtures.