Foam Sealing and Painting Questions

Hi all, first time posting. I'm building out an iron man suit with EVA foam. I got a couple test pieces I've been working with but I think I could use some pointers on sealing and glossing.

This first piece is sealed, plastidipped, primed and painted. I'm guessing that streak is from the sealing not working well? I applied a second layer of paint on this piece and the line is still there.



This piece also has the gloss applied. But it came out dull and brownish. Any suggestions on possibly a different gloss spray or a technique?


Here's a picture of my sprays:


Thanks for any help.

im no pro but i have done a fair bit with foam.

in all honestly your streaks are probably from applying something too thick, you should take every stage stupidly slow to avoid any problems.
many fine layers are always better than less heavy ones, i know its exciting to finish something, but slow and steady is always best to avoid ruining a piece.
you should always examine closely between every stage too, rubbing down a layer if necessary.

on a side note, pva works a treat too if the plastidip gets expensive.

Second yishles, you have to do everything REALLY slow and in REALLY thin layers, otherwise it can ruin the whole thing. I always sealed with modpodge, but that takes forever. Good luck!

Thanks for the tips. I was using an Elmer's Glue/Water mixture to seal. I've switched to modge podge. Can I prime directly to the modge podge? Or do I need to plastidip it before priming?

Both modge podge or Elmers will work; How many coats PVa mix (Elmer's) did you put on? Eva can suck up a lot of sealer (and Plastidip, and paint), I usually put on at least 2 coats minimum.

You can prime and seal right over without Plastidip, but if you've got it I'd use it. Plastidip helps to both hide more imperfections in the surface, and also create one cohesive barrier layer between the base work and your primer/paint. Primers and paints seem to like it as well, at least I've never had lifting problems with it. Good luck!

I'm not sure, I've done far more than two, probably 8-10 now and I'm still seeing lots of little dark grey holes when I apply a new layer. I'm using this foam http://www.sears.com/best-step-antifatigue-foam-floor-mat-black/p-00914118000P

Is there some technique that I'm missing on the sealing part? I'm just using a standard paint brush and covering the entire front of the piece and the edges. Then letting it dry for a few hours. Each piece is sitting on a plastic cup or a cut papertowel roll tube so they're not touching the cover while drying.

Again thanks for the replies.

I use those mats quite a bit, good stuff to work with. How thin are you mixing your glue? It sounds like that could be the problem. Here's exactly what I use for glue:



I thin it VERY little, probably a glue-to-water ratio of 8:1 even, so that it's runny but not too liquid. I use a regular brush, and brush it on as thinly as possible. If you do it this way, you are going to get runs and drips; I wait about 15 minutes after coating the piece, and then go back and brush out the runs or drips with a slightly wet brush. I also come back one more time after 45 minutes or so, and wipe off any areas that are still showing white (it's usually at corners or at edges where it pooled). It's important to get these runs off before they dry, otherwise if you try and remove them later it can lift the sealer coat in that area.

I've sealed foam in A LOT of ways, and while this requires a little extra attention, it works welle. PVA seal coats will still want to crack and craze if you flex the foam too much, but following over all of this with Plastidip prevents a lot of that. I'm thinking maybe you've got too much water in your glue mix, and after it evaporates your PVA is left too thin. That's just a guess though. Two-three coats done as above, with a good three hours of drying between them, should leave you with a glazed-looking sealed surface of PVA, and no pinholes anywhere.

That seems like overspray to me... too heavy of a spray, especially concentrated on one spot, can cause that. I've made the same mistake when there seemed to be a spot that wasn't covering properly (like an edge) so I'd spray it really heavy there to 'get the spot'.

Also, in my experience Rustoleum products don't always play well with other brands. I had many problems with Rustoleum 'repelling' other paints (the new layer would bead up over the Rustoleum) where I never had that with the Krylon. Duplicolor and Krylon are made by the same company and I haven't had had issues pairing the two yet.

DRG said:

That seems like overspray to me... too heavy of a spray, especially concentrated on one spot, can cause that. I've made the same mistake when there seemed to be a spot that wasn't covering properly (like an edge) so I'd spray it really heavy there to 'get the spot'.

Also, in my experience Rustoleum products don't always play well with other brands. I had many problems with Rustoleum 'repelling' other paints (the new layer would bead up over the Rustoleum) where I never had that with the Krylon. Duplicolor and Krylon are made by the same company and I haven't had had issues pairing the two yet.

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I am a big fan of Rustoleum, but I will wholeheartedly agree with DRG above. Several of the Rustoleum blends are very chemically 'hot', and will react to even their own paint if you spray too soon or in a poor enviroment. Their Painter's Touch brand, for instance, recommends 24 hours dry time, but I've seen it destroy finishes sprayed over the top if it wasn't given at least 36 hours to completely cure (this is including the exact same can and color lol). Anyways, mixing across brands, nevermind different types of paint (i.e. lacquers over enamels) can cause all kinds of unpredictable reactions as well.

laellee said:

I am a big fan of Rustoleum, but I will wholeheartedly agree with DRG above. Several of the Rustoleum blends are very chemically 'hot', and will react to even their own paint if you spray too soon or in a poor enviroment. Their Painter's Touch brand, for instance, recommends 24 hours dry time, but I've seen it destroy finishes sprayed over the top if it wasn't given at least 36 hours to completely cure (this is including the exact same can and color lol). Anyways, mixing across brands, nevermind different types of paint (i.e. lacquers over enamels) can cause all kinds of unpredictable reactions as well.

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Thanks for the info laellee.

I have a few questions.

1. Do you seal your foam with a heat gun before Elmer's glue and Plastidip?

2. I assume you use multiple coats when you paint. So do you have to wait 36 hours before you recoat it in the same color?

3. This is a little random, but what color Plastidip do you use?

4. Do you clear coat the painted pieces? If so, what product?

5. These are the paints I'll most likely use.

Rustoleum 2x flat grey primer, , Rustoleum 2x gloss colonial red. , and Rustoleum bright coat metallic finish gold.



Have you used these before and did you like them?

I can answer a few of these...

Bogleo said:

1. Do you seal your foam with a heat gun before Elmer's glue and Plastidip?

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Before. I actually heat seal my individual foam pieces before gluing the part together (but after cutting them out first). This is because the heat gun can distort the shape of the foam and/or melt your hot glue.

Bogleo said:

3. This is a little random, but what color Plastidip do you use?

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This depends on what color you're putting over it. Using grey primer I'd avoid anything darker or drastically different colorwise as it requires more layers of paint to cover.

Here's what I do...

1) I do not use a heat gun on my mats before building.... I reverse-roll the tubes to take out the curve, and then just hand-straighten while I'm building. Once pieces are together, I do run the heat gun over the surfaces to tighten them up a little and lock the shape in. You've gotta be crazy careful with a heat gun on glued foam, moving it constantly, or your seams will separate. I just do it enough to make the surface sheen/color change slightly.

2) Depends on the colors you use. With the Rustoleum 2X, ignore the can directions. I recoat after about 10-15 minutes, and repeat until I've got the surface built as much as I want. If I recoat in THE SAME COLOR after that, I wait about a day. Could probably shoot sooner, but I don't. It does recoat VERY nicely though in the same color.

3) BLACK. Always black. It makes colors (like the red especially) pop better on my stuff. I've heard of color-matching with it (use red plasti under red paint, etc.) but I see no real advantage to that.

4) Depends on what I'm spraying. Those Rustoleum 2X paints (in gloss) lay on with a lacquer-like finish, really nice, and I think you'd be opening up a huge can of worms trying to clear-coat over it. I do clear coat other finishes, but it all depends on the project.

5) A few things lol....

a) If you're using those and plastidipping, skip the primer. You won't need it, save the money or get extra Plasti and lay on a couple of more coats to smooth your panels.. Plasti's finish gives you an awesome idea of how your paint coats will come out and what will show.

b) If you're layering your coats, DEFINITELY let that 2X cure at least a couple of days before using the Rustoleum Metallic finishes, the longer the better. If you spray too soon, those Rustoleum metallics will chemically react with the 2X and craze the whole surface out, ruining the finish. I've had this happen even after 48 hours of curing, if it happens you'll have to sand it all down and refinish.

c) If you have a choice to mask a color, you'll want to tape the 2X color and not the metallics... Put another way, Spray your reds, let it cure, and THEN mask the red to spray in the gold... The 2X masks really nice once it's cured, I've never had problems with painter's tape pulling up the finish. I can't say the same for the Rustoleum metallic finishes... :rolleyes

I'll confirm a lot of these comments. Here's my hit list:

- heat gun during building to preshape pieces makes much cleaner build = less worry about cleanup in finishing
- light heat gun after build seals missed spots and can eliminate slight hot glue overages (key word here is LIGHT heat gunning)
- fill in gaps and smooth seams with ElastoPatch. Not sandable, but some warm water and application with your fingers will do the trick
- Plasti-Dip, brush on, never spray
- mod Podge (or PVA, white glue, whatever) and PD, sponge applicators never brushes
- paint: duplicolor and their adhesion promoter. You won't need any other primer when painting on PD

Thank you so much everyone.

If it wasn't for you and the RPF, I would not have my very own Iron Man suit. Especially laellee, you have answered so many of my questions, you're probably getting tired of them by now.

No problem, dude. Happy to share, the only reason I know how to do most stuff now is because I did it wrong 4 ways first :lol

laellee said:

No problem, dude. Happy to share, the only reason I know how to do most stuff now is because I did it wrong 4 ways first :lol

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Haha! For real! I've been tinkering with my Mk VI for 2 years. I keep discovering new tricks and going back over it.

Sorry to bump this really old thread, but I learned a lot from reading it. Thanks everyone!

Would mixing a tab of water color or acrylic paint to the pva glue water mixture cause any negative side effects?
Side note: I know this isn't really a painting/sealing question, but it is a help related one.
Should I be wearing a mask when cutting foam with a knife? I just want to be safe is all.