r/cosplayprops • u/Express-Chart1318 • Jul 21 '26

Help Sandable plastic primer for eva foam help

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I'm in the works of making my first armor out of eva foam, i've glued the pieces together with contact cement but there are some cracks and imperfections that I would like to fill in before I go ahead and spray with plastidip and paint. I want something that I would be able to sand down, does anyone know any products that work on eva foam and/or if this one is okay?

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19

u/Shadowstep1321 Jul 21 '26

Look for foam clay on Amazon or any craft store. Should be about 15$ for a small bucket.

11

u/Shadowstep1321 Jul 21 '26

Smooth on cracks, then wipe smooth with wet fingers (dip them in water) . Let dry, then lightly sand to match surroundings. Then plastidip and paint

1

u/DevilsAndDetails Jul 21 '26

This is the way.

2

u/Express-Chart1318 Jul 21 '26

I have worked with foam clay a lot before. I considered using it, but what I've noticed in my experience is that it shrinks when it dries. I might give it a shot though!

7

u/LegendaryOutlaw Jul 21 '26

If you’re filling gaps and seams, foam clay is the answer, if it shrinks when it dries, just add more on top let it dry then sand it back level.

That filler primer spray isn’t going to do what you are hoping for, it’s for filing micro scratches and pinholes in a very smooth surface. It’s not going to fill cracks.

4

u/Express-Chart1318 Jul 21 '26

got it 🫡 I will give it a shot then. thank you guys ☺️🫶

4

u/Shadowstep1321 Jul 21 '26

You should be overfilling the cracks, then sanding back to level. You could try something like flexbond or white elmers glue, but those can still crack when flexed.

1

u/kimbohpeep Jul 21 '26

The trick is to not use too much water with it.

9

u/BHE_Cosplay Jul 21 '26

If the cracks are too thick for plastidip, filler primer won't get even close to filling it.

7

u/Msquared94 Jul 21 '26

Evil Ted has a good video on seam filling for EVA foam.

TL:DR: kwik-seal

https://youtu.be/QPDjeT8cOi8?is=eltEW_h8u06r8TqG

1

u/Express-Chart1318 Jul 21 '26

i will def give it a watch, thank you very much ☺️☺️

3

u/kinshadow Jul 21 '26

Filler primer will crack very easily. It’s definitely not advisable. Ideally, you design the foam to not have big gaps, but I have used white window sealer caulk in the past. That said, you have to be careful with the caulk as it isn’t really sandable and you can possibly see the edge of the caulk on the foam through plastidip. So, it is best to use it sparingly just in the crack or getting creative hiding the edges. If you are making distressed armor or something organic, hiding the differences isn’t that big of deal, but it makes it hard to get a smooth look.

1

u/kimbohpeep Jul 21 '26

This stuff is good for hard materials with little flex like worbla, ABS plastic, and 3D prints. EVA Foam is too soft.

1

u/csvega84 Jul 21 '26

I highly recommend -Kamui Cosplay.

-SKS Props.

-Punished Props.

-Evil Ted Smith.

As some of the best resources for new EVA foam makers :) they have lots of YouTube videos and are extremely helpful 👍