Amazon.com: U.S. Art Supply Acrylic Retarder Acrylic Medium, 200ml Tube (6.7 Ounces) - Mixed with Color gives you longer Working Times : Arts, Crafts & Sewing
Golden Acrylic Retarder | BLICK Art Materials
Slow Down Drying Time with the Best Retarders for Acrylic Paint
Golden Acrylic Retarder | BLICK Art Materials
How to blend acrylic paints like oil paints/Retarder medium for acrylic paints/Easy colour blending - YouTube