blister polyurethane painting

[ras85]

t my company, there was a pump with epoxy painting, because of painting low quality, pump was painted with polyurethane painting, but after just 20 days the painting blisters. It seems there are different reasons such as, not prepare surface properly, or three layer painting should be applied(i mean apply primer, intermediate and then polyurethane top painting)and ....
However a guy told me that the polyurethane never blister on epoxy painting, so maybe the painting was counterfeit. please let me know if someone has similar experience?

 

[berkshire]

It sounds as if you have substrate with solvents in it.
Poly urethane paints will pass solvents until they fully crosslink.
If all of the solvents have not evaporated by then they will be trapped and cause blisters.
B.E.

You are judged not by what you know, but by what you can do.

 

[Compositepro]

Any paint can blister for a variety of reasons. Most urethane paints are moisture curing. The solvents evaporate to leave a viscous coating that reacts with moisture in the air. This reaction releases CO2, which will create bubbles and blisters under some conditions. The usual cause is applying too thick of a coating. A thick coating will "skin-over" which means that uncured coating is trapped under a cured layer. This will cure slowly but the CO2 will create bubbles rather than slowly diffusing to the surface to escape.

 

[ras85]

thanks friends, is there any experience that how much time after applying, blister of painting happens? it depends on painting thickness?