A great permanent flexible primer for canvas, board or even paper. An intense black ground with an excellent tooth for easy paint manipulation. Matisse MM25 Black Gesso is a water-based product and can be thinned down with water. Use equal parts of water to MM25 Black Gesso when working on raw canvas/linen. If working on canvas, MM25 Black Gesso will tighten the canvas, making a firmer ground to paint on.