If it is 100% cotton canvas! it will shrink tighter on the board if you spray with water. I have made a large board to go on top of my board and I spritzed it several times after I stapled it to make the fabric tighter. I also made a slide on pillow case type cove that I can take off and wash. When it gets yuckie, I whip a new one up out of inexpensive muslin...keeps the original board looking nice.