Sign foam not taking paint.

[UberDapr]

A company I install for is having trouble painting some sign foam and they can't seem to figure out what the issue is.They have painted the same material before with with the same paint and no problems, but this one is just proving to be difficult.

I thought it could possibly be moisture in the air lines when painting or moisture within the material itself, but to the touch the imperfections feel rough and porous.

Have y'all ran into this issue before? Is this something you can save or would you just scrap the material and cut a new one? I won't see them till after it's delivered, but would be some useful knowledge for the future.

 

[GaSouthpaw]

Best I can remember (been a minute since I used/worked with HDU), you have to prime/sand/prime again until you have a good surface (no holes that the paint can migrate/soak into). Once you have a smooth surface, painting usually is a snap.
From the photos, it looks like it wasn't primed properly, but I've been known to be wrong on occasion.

 

[Gino]

^^ what he said ^^

 

[visual800]

you gotta blow it off real good and i use a good flat latex paint, spray it and then topcoat with 2 coats of a good latex eggshell or satin

 

[JBurton]

Yeah, thick paint, or lots of coats. Where's signbrad? He has a great write up on painting it with Matthews, but the one thing I recall was a polyester based primer that helped fill in the pores.

 

[John Miller]

I'll bet it's a primer issue. If the paint isn't latex, (I have no experience with that on signs) moisture in the air lines or damp atmosphere will cause the paint to blush
which gives a blotchy finish.

 

[UberDapr]

They were using a Behr Exterior Paint. Not sure on primer though

 

[Limitlessfabrications]

Definitely have to sand and blow off very good. We also use an adhesion promotor.

 

[UberDapr]

Which adhesion promoter do you use? I suggested Akzo-Nobles as I used it when I painted acrylics, but they didn't want to try anything they haven't used before.

Definitely have to sand and blow off very good. We also use an adhesion promotor.

 

[UberDapr]

Definitely have to sand and blow off very good. We also use an adhesion promotor.

Grip-Gard was the one I used