375ml. Applied prior to painting, FAS™ Gesso Primer is a fast drying waterproof primer/sealer, preventing moisture loss through absorption which causes paints to dry too quickly. Ideal for canvas, board and most painting surfaces, can also be used to give texture or 'tooth' to the painting surface. Seals absorbent surfaces to an prevent uneven appearance and excessive fast drying, resulting from paint penetration. In an undiluted form Gesso may be textured, but dilute with a little water if only sealing is required.