Ruined a full week's work with one bad can of spray primer

I spent 6 evenings shaping a foam Mandalorian helmet, got it smooth with filler and sanding, then sprayed it with a new can of primer that bubbled and cracked the whole surface. Has anyone else had luck with a specific brand of filler primer that doesn't eat through foam?

2 comments

2 Comments

stella6141mo ago

That's a gut punch man, I feel your pain. I had the same thing happen on a set of pauldrons I was making for a friend's cosplay, spent like three weeks getting the shape perfect and then hit it with a can that basically melted the foam into a crinkly mess. The trick I found is you gotta seal the foam first with a couple light coats of something like Mod Podge or even watered down PVA glue before you even think about primer. Plastidip makes a good spray sealant that has never given me trouble, it goes on rubbery and doesn't eat through EVA foam at all. Just make sure you let each coat dry completely before the next one, rushing that part is what got me the first time.

marywells1mo ago

That thing about rushing the drying time is probably what tripped me up too, @stella614. Did you find that the Mod Podge worked better than the Plastidip for preventing that crinkly melt effect, or is it more about the application method? I feel like I see people swear by both but nobody ever explains why one might be better for a specific foam type. I'm wondering if I should just skip the primer altogether and go straight to the sealant coat next time.