On Wednesday, 20 May 2020 16:31:34 UTC+1, Martin Brown wrote:
On 20/05/2020 15:49, tabbypurr wrote:

Some south facing exterior timber window frames were painted with
Leyland undercoat & gloss topcoat, both oil based. The wood was in
sound condition, and the old paint was all stripped off due to its
poor condition. Now the paint is flaking badly a year later! How can
a repeat of this failure be avoided?

That is a fairly decent quality paint

I've always been happy with Leyland, pretty good stuff. But this batch was problematic to apply. It had no interest in covering even the tiniest of microcracks on the previous paint, so every little bit had to come off.


so it almost certainly has to be
bad preparation of the surface to be painted or moisture still trapped
in the wood when it was painted. Frost or excessive temperature
variation before the paint had fully cured might be a possibility too.

Do you have a picture of a flake (underside) and the surface it flaked off?

It is the top coat only or is the undercoat and top coat coming away
from the wood surface. South facing is the most stressful direction for
a painted surface to face but it should last a lot longer than that.

Surface prep was a thorough scrape off. No chemicals were used, no water. All cracks were filled with linseed putty, which I've never known to have a problem with alkyd gloss. Layers applied were Leyland undercoat (alkyd) & Leyland gloss topcoat.
The wood was dry.
Weather was too warm for frost.
I'll pull some flakes off later for closer inspection.


NT