Jo Sonja Gel Retarder is an acrylic medium designed to delay the drying time of Jo Sonja Matte Flow Acrylics without reducing the viscosity of the paint. It is used to extend working time for blending, antiquing, and techniques that benefit from a thicker application of colour.
It can be mixed directly with paint, applied to the surface to keep it open for longer, or used to thin colour for antiquing effects. Because it greatly delays drying, extra time should be allowed for the surface to dry and cure fully before varnishing. A barrier coat of Jo Sonja Flow Medium, Magic Mix, or Clear Glaze Medium is recommended before final varnish application.