Ooops, my bad! I forgot to include the use of acrylic glazing liquid in my list of ways to keep acrylics workable longer (see my post dated 11/19/15.) Glazing liquid is a real workhorse in the studio. The basis for mixing glazes -- thin applications of transparent colors over previously painted surfaces -- it's formulated to keep acrylic paint "open" long enough to cover those surfaces so that the glaze goes on smoothly and doesn't dry too quickly. But it can also be added to paints on the palette to slow down their drying time. While glazing liquid won't keep paint workable as long as Open Medium does, it does extend their working time and makes blending easier.
©2015 Lynn Edwards