Top coat (gloss) bubbles in the sun?

[ericmark]

Painted 4 sides of the building, only a problem on the side which got the sun, bubbles formed in the paint. I will guess paint too thick, and a skin had formed before paint under skin had dried, but I was not really painting it thick, so to get any thinner it would need white sprite added, not sure if that will help or hinder, the painting was on bottom three slats, next lot will need scaffolding, so easy to rub down and fix the existing problem, but scaffolding will need removing each day for trains to pass, so really looking for one coat cover on the signal box cladding.

Most of the painting was done before the wood parts were fitted, all done undercover in the running shed, can't use different makes, as heritage colours for GWR. I don't rate the paint, even some 3 weeks after painting, handling the wood, and we find paint on our hands, and we have had it pealing off, in less than a year on platform benches, but others with same paint and same painter (me) have done 5 years without a problem, but for benches we have moved to plastic instead of wood, as that should outlast my lifetime, we are putting angle iron under the plastic to stop it warping.

I had in the past blamed the cold for the paint not setting etc. But it seems also a problem in the heat?

 

[Wayners]

I know some undercoats can't get wet as there are breathable. Water gets through them.
So you need to make sure they remain dry after undercoating.

Also check the wood is dry. If paint is cracked or peeling then water can get in the wood. If you paint over trapping the moisture that can cause problems.

Undercoat cure time. Some undercoats take 7 days to cure. Cute time and recoat times are not the same thing. 2 hour recoat but 7 days cure. Means you can get two undercoats on in 4 hours but top coat can be applied in 7 days. You need to read the application data sheet for the paint which is online and follow it.
It's a simple read with all the information you need.

Also dark colours absorb heat. Black gloss can bubble in sun. White is ok

 

[ericmark]

All new wood, got pre-treated, and 7 days between coats, as only volunteer once a week. We are trying to make the signal box look more heritage, a bit odd, as normally see wood building clad in brick, this is reverse.

we are making it look as if a wood building, as that fits the look for the period, this is the box the other end of the line. So want them to better match. Most the wood was painted before it was put up, but we did not have the undercover room for the cladding, so not being painted until after being put on. We are behind time, and now trains are running, not so easy to do the work. So to return to patch up where bubbles have formed, is not want I want.

 

[Wayners]

I think you are doing the right thing then.
Maybe more a paint problem than anything you are doing.
Really they should let you use more modern paints as the old oil gloss is not the same product.
Colour matching is not a problem.