Restoring Blemished Surfaces for a Good Finish. Dwelling interiors are usually lined with half-inch-thick drywall, however certain areas, resembling between a home and attached garage, require thicker, fireplace-rated drywall. Even a chunk of scrap drywall will work, so long as it has straight edges. End all repairs with a final gentle sanding to make sure a satin smooth end and seamless mixing between the patch and the wall. Immediately apply a lightweight coating to the topside of the tape, tapering it out onto the wall. You can even make your personal backerboard from a piece of scrap plywood or drywall.…