Although large amounts of these tiny hollow synthetic glass spheres can be added, do not to make the mix too dry. In smaller quantities Microspheres make subtle textural effects. Use with Impasto Medium, Gel Medium, Polymer Matt Varnish (water-based), Gloss Varnish and Gloss Medium, Polymer Satin Varnish (water-based) or Matt Gel Medium. Mix only as required, as mixture continues to thicken.