Gel Medium: A translucent paste for impasto. glazing and texturing. Dries quickly to a water resistant finish. Increases transparency and gloss. Gloss medium: A slow drying thinning medium. Increases gloss, flow and transparency. Matt Medium: Quick drying thinning medium for acrylic colors. Gives matt finish. Retarder: Retards drying time. Does not change consistency of texture. Increases transparency.