From extensive environmental testing on Scath's paint over 5 years it became clear that Liquitex's Gloss Medium and Varnish was insuffient to protect the paint. It was too porous, depsite being labeled "varnish". After more research I chose to use the Gloss Medium as a base clearcoat because of it's thickness, and to finish the clearcoat with Liquitex's High Gloss Varnish. The latter actually is a varnish, and will seal the paint's pores to prevent staining. More durability testing will be undertaken to determine how many coats is ideal and if any waxes are needed or desirable.