MDF Window Sil Gap

[bezzas]

Hello All,

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?

Thanks

Andy

 

[imamartian]

What about using a thin strip of timber and gluing it in? Possibly set it half a mil below the level of the sill. Fill, sand, paint... etc.