Painter's canvas drop cloths are sold at home supply centers or online paint stores. Heavy weight is 8-ounce cotton canvas; premium heavy weight is 10-ounce cotton, and super heavy weight is 12-ounce cotton. Other drop cloths are blends of cotton and polyester, which reduce wrinkling. Heavier weight, more tightly woven canvas fabric shrinks less and does not tear as easily.
Drop cloths have pre-sewn edges that make slipcover construction easier. Place the long pattern pieces to take advantage of these already sewn edges. Use the drop cloth selvage edge as the ready-made edge for a tailored slipcover skirt style. The heavier weight canvas is more difficult to gather into a ruffle-type slipcover skirt. Heavy weight canvas drop cloth fabric is more durable and longer-lasting than lighter weight canvas.
Slipcover styles include no skirts, tailored skirts and gathered skirts. Gathered skirt slipcovers use the most fabric yardage. A straight-arm style, two-seat sofa requires 10 to 14 yards for a no-skirt slipcover and 18 to 25 yards for a gathered skirt slipcover. Large drop cloths are 12 feet by 15 feet. An average size sofa slipcover without gathered skirt can be made with two large size drop cloths.
Prepare the Fabric
Cotton canvas drop cloth fabric has a stiff feel that is removed by washing with mild detergent. Use bleach if a whiter color is desired. Washing also prevents the fabric from shrinking after the slipcover is sewn. Cotton polyester blended fabric does not need ironing, but all-cotton fabric wrinkles. Iron the pieces after they have been cut for the slipcover pattern.