Gesso alone will not stop SID; a sizing must be applied before using a gesso. Contemporary grounds include acrylic gesso, gouache and commercially prepared claycoat papers. He is attributed with the revival of gilding with gesso and gold leaf on vellum. Art supply manufacturers market canvases pre-primed with acrylic gesso. These crude retablos were coated with a gesso made with gypsum and rabbit skin glue. Modern acrylic "gesso" is made of titanium dioxide with an acrylic binder. Acrylic gesso is very difficult to sand. Images were painted on both sides and painted over with a white gesso. Panels were prepared with a "gesso", a mixture of glue and chalk. The tracery is of the very finest, chiefly gilt on backgrounds of diapered gesso. The artist might apply several layers of gesso, sanding each smooth after it has dried. It is frequently used on canvas, whereas real gesso is not suitable for canvas. MD Weems uses homemade gesso to sculpt texture into her artwork. This layer helps to "tone" the canvas and to cover the white of the gesso.