The Natural Philosopher wrote:
stuart noble wrote:
Dave Plowman (News) wrote:
In article ,
stuart noble wrote:
If u can get the wood dry, and then apply a very runny resin to it
that soaks into the rotten fibres and stabilises (and seals
against more water ingress)
That's an essential preparatory step, IMO, and proprietary 2-part
'wood hardener' products are available for the purpose. Any
decorators' merchant will have some.

Fibreglass resin is cheaper, and essentially the same thing

It's a lot thicker than the stuff I tried, so would it actually soak
into
the wood?


IME, yes. It soaks into porous wood, partly because it cures more
slowly than the resin used in body filler (overnight IIRC)

That depends on how much catalysts you add.


Put enough in, it sets in a minute or two and gets hot enough to catch fire

Without an accelerator (cobalt?) a thin film of layup resin doesn't cure
that fast because the heat is constantly being cooled by the air and the
surface itself. There are all kinds of accelerators and retarders to
overcome this e.g. when large items are being laminated outdoors in
winter. Overloading the resin with a lesser catalyst would weaken the
end result.
Filler is a different matter because a) the resin itself is more
reactive, and b) there is usually a greater depth. If you skim it on to
a sill, it will will still be soft when the hole you filled has long
since cured. It always does cure eventually though