Knotting question

I’m about to paint new window frames and doors on a property that I’m refurbishing but there are a lot of knots that need dealing with first. How can I ensure they don’t exude resin and spoil my handiwork?

Resin exudation is an age-old problem that can occur on all sorts of wood, new and old. It can even be triggered off by changing the colour of paint used to decorate the wood. Changing from a reflective light colour to a dark heat absorbing shade for instance can be enough to cause resin to be released from knots that previously gave no cause for concern.

If the problem isn’t too severe, use a hot air gun to force resin to the surface, wipe down thoroughly with meths and then apply a proprietary knotting solution. Using an MPV decorative coating should also help. However, there’s only one way to be absolutely sure that no resin will be exuded in the long term, and that’s to drill the knot out completely and then fill the hole with woodfiller.