Atelier - Acrylic Varnishes - 250ml - Matte Medium & Varnish - Atelier Interactive Matte Medium Varnish is water based, non-toxic, self-leveling and can be used either as a medium to change the sheen levels of acrylic paints or as an over-varnish for acrylic painting. Atelier Matte Medium provides a non-tacky protective coating. Atelier Matte Medium Varnish is creamy, mid-viscosity. Product made from hard acrylic emulsion. Matte Medium is non-removable, however it can be overpainted.