Need help properly coating/painting EVA foam

NoWimps · Jul 17, 2014

Hi! I'm new to the discipline of crafting armor and props. I am currently making my first set of armor from a combination of pep and EVA foam. I have read many conflicting articles regarding how to properly coat and paint the EVA foam. Is there a go to guide out there with the information I need to help create high quality finishes for foam?

So far I am aware of the following for prepping before paint:
PVA
Wood Glue
Collapsing the foam cells with heat
Plasti dip

Thanks in advance!

JMChabot · Jul 17, 2014

Might want to look at Evil Ted's videos on YouTube. Here is a sample http://youtu.be/SqntVM0jRI4

My weapon of choice is PlastiDip.

laellee · Jul 17, 2014

I've built quite a bit, and I settled on this process for EVA:

1- Finish building the piece
2- Float the heat gun over all of the surfaces to tighten and set the surface. Don't go crazy or hot-glued seams will separate.
3- I look over the pieces for pinholes or openings in seams, and fill these with paintable silicone caulking. I just use my finger to smear it in, then let it dry.
4-Mix PVA glue and water at about a 4:1 ratio, I try to get it a little thinner than house paint. I paint on my coats as thin as possible. I check the pieces a couple of times in the first half hour, brushing out any runs and pooled areas in corners and joints; if you don't get them out when they're wet, they're much harder to clean up later. You can get away with 2 coats, but 3 or more gives you a much better finish.
5- I then follow up with a couple of coats of Plastidip (spray). Some people paint right over the PVA coats, with good results. I noticed on my pieces, especially flexible sections like the abs and gloves, that repeated flexing created cracking and fissuring in the PVA. A couple of coats of Plastidip seals the PVA, hiding most all of my cracking. It also gives the pieces a uniform color over the PVA, so I can catch any extra imperfections that I didn't see in the PVA coat.

Anyways, that's what I do, and it works well. Some people don't like the expense of the Plastidip, but I think it's well worth the extra spending.

- Just to add, in regards to the PVA and Plastidip: EVA foam sucks up both glue and Plasti. You can seal pieces in just Plastidip, but you'll have to use quite a bit more than if you had applied a PVA sealer first.

mdb · Jul 17, 2014

Yep, best way to approach this is to think of the properties of EVA:

It's very flexible: s the glue you use to join pieces needs to flex and so does any surface treatment.
It's porous: it's going to soak up anything very liquid. So if you can seal and paint with products also flexible it will reduce risk of flaking.
It's water resistant: pretty majorly so, but PVA works because it also soaks in to the open cells. You will want to work carefully, I have had dilute PVA separate on the surface. So whatever you use will need a bit of working and watching.

I lovelovelove WC flexible urethane on the stuff. It sinks well into the pores and is very flexible and super glossy. I have sadly ditched the tests I made from the stuff but am very happy to redo them to highlight the pros and cons. The biggest con is the stuff it like painting with contact cement. It is not easy to brush but then it slumps and smooths out, so you need to be able to anticipate how that may affect the end result.
It is however so glossy and so smooth when finished people will ask what you have used

It also mixes really well with urethane/epoxy ready pigments. And will cast well in ultracal and is all around super.
http://bjbenterprises.com/pdf/WC-595.pdf
This is what I have been using and loving. It's sold at Barnes in Oz and we can get it here in NZ with preordering. Pretty sure other companies sell something of a similar shore and clarity

Talaaya · Jul 18, 2014

Personally I like using foam as a way to create shapes and thicknesses and use worbla, a thermoplastic, to cover it. I'm not sure this counts for what you're asking for but maybe it's worth mentioning. It may also be out of your price range, as worbla isn't exactly cheap. If you want a good smooth finish you have to coat the worbla in something since it's a bit bumpy. You can use wood glue, or gesso, or bondo (careful to apply gesso or wood glue first, as bondo peels off of worbla), or my new favorite: Apoxie Sculpt. Apoxie gets kinda heavy though.

Here's some before and after pics:

A 5mm foam piece of armor

Here it's been covered on the outside with worbla

The worbla does a few things that other techniques do not:

- it hardens the shape, creating a strong, rigid piece. Depending on the shape and size you may need to double layer it (usually one on the outside, one on the inside - this is where it starts getting even more expensive)
- it allows you to shape the foam (and make it stay!) in ways that you would normally not be able to. Take this armor for example:

The right side only had worbla laid over the foam. The left side was pushed out from the inside while heated to get a much nicer round shape.

Here's a side by side comparison of raw worbla applied to foam and the final smoothed out painted version:

You can also just use worbla on its own without foam, but it's very difficult to get it to stay smooth and uniform unless you've got something to form it over.

Hope that helps! Just keep in mind there is no "right" way to make armor. Pick what fits your budget and time frame, and most of all just have fun experimenting with stuff!

Athanasios · Jul 18, 2014

Awesome tips here! I've never use foam before but I plan to, so i'll be keeping these techniques in mind.

ApophisV · Jul 18, 2014

Talaaya said:
Here's a side by side comparison of raw worbla applied to foam and the final smoothed out painted version:
View attachment 350524

You can also just use worbla on its own without foam, but it's very difficult to get it to stay smooth and uniform unless you've got something to form it over.

Hope that helps! Just keep in mind there is no "right" way to make armor. Pick what fits your budget and time frame, and most of all just have fun experimenting with stuff!

That's some amazing work you've shown us there! Which of all those options you mentioned did you use to smooth out the golden piece? I used Worbla to cover parts of my HEV suit (also EVA) earlier this year, but I didn't achieve anything that smooth! Very impressive!

NoWimps · Jul 18, 2014

First let me start by saying I feel so welcomed and encouraged by your responses, really great stuff!

I'm much more confident now and there are some really good subtleties that were covered here that I could not find from any other source. I am definitely going to give Worbla a shot even if it is not for my first project. I'm doing a few tests this evening with PVA, Plastidip, and the heat gun methods which I'm sure will all yield good results.

Started to resin harden my helmet last night!

Talaaya · Jul 19, 2014

ApophisV said:
That's some amazing work you've shown us there! Which of all those options you mentioned did you use to smooth out the golden piece? I used Worbla to cover parts of my HEV suit (also EVA) earlier this year, but I didn't achieve anything that smooth! Very impressive!

Thanks! That one was gesso'd then bondo'd. That seems to be the best option in my experience. Wood glue is hard and as a result sands slower than bondo, which can cause issues if you sand through the bondo. Gesso sands at the same speed, but either way I highly recommend avoiding sanding through layers (even on gesso you can peel bondo off if you give it the opportunity). Getting worbla that smooth takes quite a bit of work but as you can see it's well worth it.

Apoxie Sculpt is great for adding extra strength and getting crisp details (see my thread for more on this), but as I mentioned before it can start getting heavy fast. I used it because my shin armor was still flexing even with two layers of worbla, and I needed to build up edges and make them crisp. I also had to use it to rebuild a point I cut out of the back side. It's perfect for that stuff. I haven't tried combining it with bondo but I'm guessing that would work great if you had to rebuild some details but wanted to keep it light.

You can also just use wood glue by itself and either sand it or just leave it, although it tends to have bubbles if you don't sand it. I used only wood glue on my glove worbla. Took forever to sand because the glue sands so slowly, but it turned out great. I figured trying to apply bondo to such small pieces wouldn't be fun.

The glove pieces have no foam by the way. I just formed it around my hand, double layered on the palm and single layered for the fingers because their small, rounded shape made them strong.

SMP Designs · Jul 21, 2014

On the Plasti-Dip, I never use the spray, only the brush-on. The brush-on is much better at self-correcting and smoothing out as it cures than the spray. Also, if you're working in hot weather, you can literally watch the PD cure in about a minute. Keep to a cooler area if possible and have some Naphtha handy for smoothing and thinning PD that's getting goopy.

I've also used a product called ElastoPatch to fill in gaps and smooth seams. It's not sandable once cured, but it's pretty easy to deal with by applying with your finger and keeping a small bowl of water nearby to smooth it. It retains its flexibility after curing (v. v. Important when building in foam) and PD goes over it brilliantly.

As for the PVA, I don't use it, personally. I just heat seal the foam and then PD directly onto it. But, then, I use the brush-on PD, not the spray. So that my make the difference.

For paint, I've used automotive paint along with an adhesion promoter and that has worked well.

NoWimps · Jul 21, 2014

Thanks for the tips! I have been doing some small tests with the options you all recommended and they work very well!

Had a chance to work a little this weekend and made some progress on building up my chest piece. Looks rough now but with some more shaping and application of paint should really look nice!

Mexicutioner46 · Aug 17, 2014

So I have a question about this Worbla: You heat apply it to a foam backing, so that the sheet takes the shape of the foam correct? In the pictures, the texture looks very rough (speckled like sand paper). Do you have to sand it down for it to be smooth, like the pictures shown? How much work is it from applying the worbla to the foam, to primer stage? Sorry for so many questions, but this is the first time I've heard of Worbla.

infymys · Aug 17, 2014

Mexicutioner46 said:
So I have a question about this Worbla: You heat apply it to a foam backing, so that the sheet takes the shape of the foam correct? In the pictures, the texture looks very rough (speckled like sand paper). Do you have to sand it down for it to be smooth, like the pictures shown? How much work is it from applying the worbla to the foam, to primer stage? Sorry for so many questions, but this is the first time I've heard of Worbla.

People usually put on a few coats of gesso on the Worbla and then sand it to get a smoother texture. If you want more tips on working with Worbla, I highly suggest checking out Kamui's YouTube page. I don't think many, if any, will disagree with me when I say she's the master of working with the stuff.

Annisse · Sep 5, 2014

Talaaya said:
Thanks! That one was gesso'd then bondo'd. That seems to be the best option in my experience. Wood glue is hard and as a result sands slower than bondo, which can cause issues if you sand through the bondo. Gesso sands at the same speed, but either way I highly recommend avoiding sanding through layers (even on gesso you can peel bondo off if you give it the opportunity). Getting worbla that smooth takes quite a bit of work but as you can see it's well worth it.

Apoxie Sculpt is great for adding extra strength and getting crisp details (see my thread for more on this), but as I mentioned before it can start getting heavy fast. I used it because my shin armor was still flexing even with two layers of worbla, and I needed to build up edges and make them crisp. I also had to use it to rebuild a point I cut out of the back side. It's perfect for that stuff. I haven't tried combining it with bondo but I'm guessing that would work great if you had to rebuild some details but wanted to keep it light.

You can also just use wood glue by itself and either sand it or just leave it, although it tends to have bubbles if you don't sand it. I used only wood glue on my glove worbla. Took forever to sand because the glue sands so slowly, but it turned out great. I figured trying to apply bondo to such small pieces wouldn't be fun.
View attachment 350793
The glove pieces have no foam by the way. I just formed it around my hand, double layered on the palm and single layered for the fingers because their small, rounded shape made them strong.

WOW! I can't believe your glove here is only layered with Wood Glue over worbla. That is amazing! I used wood glue over a helmet I made with worbla and did not get that smooth of results as you have here and I used about 6 layers of wood glue and sanded it. Can I ask how many layers of wood glue you used on each glove piece here and did you wet sand or dry sand? Thank you! Awesome work!

Blackluc · Sep 6, 2014

I see you are making a Clayton carmine build? Check out mine

anyway, good tips here in this thread! I'm not a foam expert but I just used a heat gun and plastidip and honestly the result is pretty good. But I already had a nice surface.

Talaaya · Sep 7, 2014

Annisse said:
WOW! I can't believe your glove here is only layered with Wood Glue over worbla. That is amazing! I used wood glue over a helmet I made with worbla and did not get that smooth of results as you have here and I used about 6 layers of wood glue and sanded it. Can I ask how many layers of wood glue you used on each glove piece here and did you wet sand or dry sand? Thank you! Awesome work!

Thanks!

If I remember correctly it was maybe about 6 layers as well. Wood glue is a nightmare to sand - I dry sanded it over and over and over to get it that smooth, and it takes a lot of finessing to make sure you get all the uneven parts. I made sure to keep an eye out for any darker/transparent spots which were too low for the sandpaper to reach (divots/valleys). Then I'd hit it with a coat of primer to check how smooth I'd gotten it (the unevenness of transparent glue is difficult to gauge), which also allows for easier visibility of unsanded areas since they'll remain the color of the primer.

From what I learned wood glue is only feasible for very small objects if you're sanding, or large objects which you don't bother sanding.

Annisse · Sep 8, 2014

Talaaya said:
Thanks!

If I remember correctly it was maybe about 6 layers as well. Wood glue is a nightmare to sand - I dry sanded it over and over and over to get it that smooth, and it takes a lot of finessing to make sure you get all the uneven parts. I made sure to keep an eye out for any darker/transparent spots which were too low for the sandpaper to reach (divots/valleys). Then I'd hit it with a coat of primer to check how smooth I'd gotten it (the unevenness of transparent glue is difficult to gauge), which also allows for easier visibility of unsanded areas since they'll remain the color of the primer.

From what I learned wood glue is only feasible for very small objects if you're sanding, or large objects which you don't bother sanding.

Thanks so much for sharing! Maybe that did the trick. Dry sanding instead of wet sanding. I have to try that next time. I wanna strip the paint off the parts of my helmet that look all bumping, re add some Wood Glue and dry sand and hope to achieve the effect you got. Looks awesome!

Talaaya · Sep 9, 2014

Annisse said:
Thanks so much for sharing! Maybe that did the trick. Dry sanding instead of wet sanding. I have to try that next time. I wanna strip the paint off the parts of my helmet that look all bumping, re add some Wood Glue and dry sand and hope to achieve the effect you got. Looks awesome!

Just be careful about adding a new layer of glue. I tried it and it wanted to peel back off, especially if I sanded through that new layer. It could have been because there was still some primer on there or something (I forget), but at least rough it up first - that might help with adhesion.

Also, if you weren't aware already, a great alternative to wood glue is gesso. It takes a while to layer up enough of it, but once you do it's much, much easier to sand than glue. Be wary of gesso peeling off too, but so long as you don't sand through it you should be fine; usually it works great.

Blasturbator · Dec 19, 2014

Ok so i read this a little too late
What i did is 3 layers of pva glue
It doesnt look even but doesnt matter
What im wottied is that some paint rubs off.
Should i use mod podge to seal it or plastidip clear?

laellee · Dec 19, 2014

I wouldn't even worry about using clear plasti, I prefer the grey or black because it lets you see any imperfections that you can clean up before finish painting. Lately I've been going 3 coats of EVA, followed by 2 heavy coats of Plasidip.

Need help properly coating/painting EVA foam

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