1. Spread your drop cloth out and cut off any seams because these are not usable. Cut the drop cloth to your desired size. If your using a pre-primed artist canvas you can skip this step.
2. Take your straightedge and a pencil to square your drop cloth along the edges.
3. Staple your drop cloth to your board and pull the fabric taut. Spray water on your stretched drop cloth to remove any wrinkles. You can also use an iron to remove wrinkles.
4. While your drop cloth is stapled apply 2 coats of gesso to the front of your floorcloth. You'll prime the back later.
5. When your drop cloth is dry take your straightedge and a pencil and square up the edges. Drop cloths will shrink and warp around the edges to some degree when you prime them so cut off the areas that have warped.
6. Turn your floorcloth over so that the primed side is facing down. Now is the time to make your hem and mitered corners. Take your ruler and place the edge of it an inch from the edge of your floorcloth. Wrap the floorcloth over the ruler to crease your floorcloth. Continue creasing your floorcloth until you've done all four sides.