Rustins knotting is used for sealing knots in wood and on resinous and creosoted timber to prevent bleeding through paint film it is fast drying and prevents discolouration of paints suitable for interior and exterior use applicationprepare the surface by first sanding it 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 knotting should not be used under polyurethane clear