I have some gaps in my guttering which I'm trying to fill with the proper mastic using a palette knife.But the mastic wants to stick to the knife rather than the guttering and keeps coming away;Any ideas please? Thanks.
I've just watched a few Youtube videos on the topic, all of which seem to suggest that the mastic should be applied directly from the tube and internally, rather than on the exterior of the guttering. So there will be no need to spread it.