- For sealing knots and resinous and creosoted timber to prevent bleeding through paint film. Sandpaper surface smooth before applying liberally over knots and surrounding area. Do not sandpaper knotting once applied. Resinous and creosoted timber should be sealed completely with 2 coats. Allow 1 hour to dry before priming. Clean brushes with methylated spirits. Knotting should not be used under polyurethane clear varnishes or waterbased varnishes and water-based paints