In message , Mark
writes
On Tue, 23 Oct 2012 19:32:23 +0100, Roger Mills
wrote:

On 23/10/2012 17:47, polygonum wrote:


Completely agree that they can raise the grain. But, in that sense
luckily for me, most of my painting is re-decorating where the substrate
is already pretty well covered.


I find that water-based paint is fine on wooden door frames and
skirtings, etc. However, what it's *not* fine on is MDF window cills if
they're ever likely to get wet. When the paint is thoroughly dry it will
still let water through - unlike oil-based paint - and this will bring
the MDF up in a nasty rash.

I wouldn't use MDF for window cills again. They all turned into
weetabix, even using oil-based paint.

OK for the last 17 years here. Oil based paint, double glazed and
radiators under the windows.

Good point about water based porosity though.

--
Tim Lamb