What Happened? 2K over Epoxy

[PatG]

Hi guys. Shot a coat of SPI epoxy, unreduced. It flashed 45 minutes. Then, shot 3 coats of 2K over it. Black spray guide coat is why it looks so ugly. I got these weird bubbles of 2K in certain areas. Had to sand each one out and reshoot. Wondering what could have happened? Just as info, it's about 90 degrees here in Sacramento when I'm shooting. Any thoughts on what might have happened? Provided a couple shots of the project and close up of two of the areas where the 2K created sort of a primer balloon over the epoxy. It only happened where there were 90 degree angle bends on panels. Flatter areas were all fine. Hey Dub, car look familiar?

Thanks

Pat

This is Drivers door jamb, back, under latch (at B pillar).

Here I poppsed the 2K primer "bubble"

This is Drivers sill, at "A Pillar- door hinge pillar"

And after I popped the bubble

Here is a photo of my project; 59 Triumph TR3A. Just finishing body work and getting ready for paint on scuttle, rear cowl, and jambs. About ready to pull the tub, flip it over and paint the underside.

 

[jeremyb]

Applied the 2k too soon. In crevaces like that, often paint will be thicker as it flows down into those spots...causing it to dry/flash slower.

I always wait a few hours before i coat epoxy with poly or primer, even when its hot. I may even wait overnight if time allows during the winter (even with heat in the booth). Also I always reduce the epoxy when using as a pre-coat. Not so much like a sealer but atleast 10-20%. This helps too, as spi epoxy is thicker than most other epoxies without reducing.

 

['68 Coronet R/T]

Also, you must let the 2k flash the proper amount of time between coats. If not solvents get trapped and can cause blisters, cracks and peeling.

 

[PatG]

Thanks for the responses. I'll need to let epoxy cure overnight, in the future.