Cosmic Shimmer Watercolour Gess-oh! is an opaque acrylic-based primer available in either 50ml or 150ml size pots. Watercolour Gess-oh! creates a watercolour-friendly base on non-watercolour-friendly papers, card or MDF. By applying this opaque base, colours will show more vividly, and your paints and inks will flow much more freely when applied! Use with your favourite brush or roller to apply.