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 paints and mediums. It is ideal for using when plain-air painting, mono printing and any other technique that requires paint to be wet for longer periods of time. For optimal results do not use more than 20% Retarder Gel with any quantity of paint. NOTE: Using a larger proportion of Retarder Gel to colour can negatively effect the permanence and film integrity of the paint.