andrewpreece wrote in message ...
I am getting this with dulux ; I bought some planed timber from a builders'
merchant,
gave it two coats of anti-rot treatment, let dry for 24 hours, then
knotting
compound over the knots ( 24 hours drying ) then primer ( 24 hours drying,
but it didn't dry properly on top of the knotting compound ), then
undercoat 24 hours etc, finally the topcoat. The topcoat really hasn't
behaved well, all these little bubbles just as described above. I dragged
the paintbrush across the paint to deflate the bubbles but got just as
many.
In disgust, I waited 24 hours 'til it had dried, then sanded and put a
second coat on, and not only got the bubbles, but the two coats of gloss
reacted with each other and have wrinkled and ridged up.

I can't see that 2 coats of the same paint should react with each other. I
would guess the rot treatment is the problem. Don't know what you used but
often they're solvent based products with very little solid material to
restrict penetration, so they can take a lot longer than 24 hrs to dry
fully. Some leave a water repellant film but presumably they are not
designed to be overpainted.