AB-03Fill any holes, cracks or dentsOn solid brick or block, and plasterboard on timber or metal studs, fill normally with multi-purpose filler and sand flush once dry. On dot-and-dab plasterboard, fill gently — pressing too hard with the filling knife can push the board off its dabs, so use light strokes. On lath and plaster, use a flexible filler and avoid heavy sanding, since the old plaster keys behind the surface can be brittle and crack further if you're rough with them.