One of the interior window sil's is MDF (don't ask).
Problem is there is a slight gap between where the sil butts up against the uPVC window frame.
I have tried filling the gap with caulk and filler but it just shrinks and cracks.
could i use Ronseal High Performance Wood Filler to fill the gap between the sil and the uPVC window frame?
will it stick to the frame?