Retarder Gel is a water-based product designed to slow down the drying time of acrylic paints. This thick gel is formulated for use with Tri-Art's High Viscosity, Liquids, and mediums. For optimal results do not use more than 20% Retarder Gel with any quantity of paint. The ideal medium for modifying your high viscosity paints for mono and screen printing processes. Adding a small quantity of Retarder Gel to paints on your palette will keep paints wet longer.