Confirmation of process for sealing EVA foam please

Don't want to see this ad? Sign up for anRPF Premium Membershiptoday. Support the community. Stop the ads.


Marthony

Active Member
Hello,

I'm about to begin adding detail, upgrading & refinishing my G1 Transformers Devastator rig, and wish to clarify a process for the EVA foam.

Here's how the rig is presently:
http://i1276.photobucket.com/albums...6-AAD1-4E5A-BE58-5FE97006E56D_zpseusj64jt.jpg
Video: http://vid1276.photobucket.com/albu...7-888F-4C22-B55C-23765A8CD729_zpsvfqu8stc.mp4
Video: http://vid1276.photobucket.com/albu...0-F484-4C92-A3AC-703447DAEEC5_zpsmqztijdk.mp4
http://i1276.photobucket.com/albums...2-9405-425B-A26B-812DE287A62E_zpsc9r8nfzf.jpg

As is, the foam isn't sealed at all. It was great for Halloween, but I want to do better.

I'm having a challenge getting consensus on the best way to seal EVA foam for painting. Note: flexibility is needed, and Plasti-dip is not desired due to need for ventilation & expense.

Please advise on my current understanding of the process:
1. Heat-seal foam pieces with heat gun
2. Lightly paint pieces with white glue, wait until clear to repaint, for 5 coats (undiluted, diluted by 10%? Help please!)
3. (sanding or re-detailing step?)
4. Paint on primer coat
5. Paint
6. Apply sealing layer such as clearcoat paint or Pledge floor wax

Other than the sealing process, I've a series of edit's I want to make but that's another subject.

Thanks!
 

Don't want to see this ad? Sign up for anRPF Premium Membershiptoday. Support the community. Stop the ads.

Ikras

Active Member
Can't see the images just now but what you've described there is basically what I did with my iron man.

Heat seal.
Then I think I had around 3 layers of PVA (maybe around 50/50 with water, I didn't have an exact measure and went more by look). Unless you put on really thick layers then you shouldn't need any re-detailing or sanding. I think I maybe sanded back a few areas where the glue had gathered and dried in a droplet. I gave each layer around 24 hours to dry. Possibly (probably) overkill but I didn't want to take any chances at that stage.

I then used spray cans for all my painting, primer, colour, then a clear coat.

It works and gives a good result but it is susceptible to cracking when it flexes overly much. I think that's one of the benefits that people like about plastidip.

I'm looking into a few alternatives just now such as watered down decorators caulk (I've heard good things about this) and liquid latex. I guess beyond that it depends on the flex you have in your paint as to whether it will crack or flex.

Hope that's of use.
 

George

Master Member
After reading this I wonder why neither one of you applied either a rubber- or plastic coating on your suit and went straight to painting?
Durability seems like a must when spending all that time and money on your project.
 

Marthony

Active Member
Ikras, how did you come to choose roughly 50/50 water/glue dilution? Did you try other concentrations, or was this by a reference?

I'd be willing to try liquid latex but haven't read about its application this way. It does sound like it would pass the emissions test, but I've no idea if it would adhere strongly enough for the task.

Thanks!
 

collinE83

Well-Known Member
50/50 is kinda the standard because you need to water it down by about that much to get rid of the brush strokes. The glue doesn't level out that well when it's too thick, and then you don't have the smooth surface that you're going for in the first place. Add any more water to the mixture than a half and half ratio, and it just takes more layers to build the glue up. And waiting for each layer to dry is booooring.

You get the cracking with white glue, so it's a trade off.

Conversely, you can use Elmer's Clear school glue and mix that into the white glue, or just mix it straight into water, like PVA. This will give you the same seal, but the glue is clear and 100% flexible. I don't know if it's in other countries, but it's right next to Elmer's white glue in stores here in the US. I've used it several times when I want a flexible seal more than I want stiffness.
 

Don't want to see this ad? Sign up for anRPF Premium Membershiptoday. Support the community. Stop the ads.

Marthony

Active Member
Great stuff, thanks CollinE83.

I'll seek out the 'Elmer's Clear school glue', as flexibility is desired.

I have a unit of Weldbond glue that seems to be similar to PVA glue, but it cracked in my test.

Using non-flexible glue to seal the hard insulation foam would be fine, but it is the EVA foam that is the tricky one...
 

Ikras

Active Member
After reading this I wonder why neither one of you applied either a rubber- or plastic coating on your suit and went straight to painting?
Durability seems like a must when spending all that time and money on your project.

It's what I want to try next time round but at the time my attempts with other kinds of coating had not worked out well at all. I know what you mean though.

Ikras, how did you come to choose roughly 50/50 water/glue dilution? Did you try other concentrations, or was this by a reference?

I'd be willing to try liquid latex but haven't read about its application this way. It does sound like it would pass the emissions test, but I've no idea if it would adhere strongly enough for the task.

Thanks!

There are some builds at the moment that have made use of it over foam I think (eg. http://www.therpf.com/showthread.php?t=252185 over a fabric coating on foam I guess) but when I can get round to it I want to give it and the watered caulk a test.
ColinE83 got the point exactly with the 50/50. I gave it a try with slightly different ratios but it just didn't work out due to those reasons.

Conversely, you can use Elmer's Clear school glue and mix that into the white glue, or just mix it straight into water, like PVA. This will give you the same seal, but the glue is clear and 100% flexible. I don't know if it's in other countries, but it's right next to Elmer's white glue in stores here in the US. I've used it several times when I want a flexible seal more than I want stiffness.

I think it might be more of a US product that. I've never come across it here but I might keep an eye out. I always thought that it was basically the same as PVA though and would have the same issues?
 

Marthony

Active Member
I haven't heard of it before, but the price difference is attractive. On the down side, it still demands ventilation which is an issue for me. Searching on the internet, I've found several references to its use on foams and it looks like a legit option. More runny than Plasti-Dip, cheaper. One reference of it not wanting to go into fine details/cracks...

On a similar note, it also has been revealed that Envirotex resin is an option. I worked with this decades ago coating a chess board. It does not require ventilation or environmental considerations. It remains flexible, though if bent back on itself it can show buckling. It can be sanded.

Interesting options..!
 

Don't want to see this ad? Sign up for anRPF Premium Membershiptoday. Support the community. Stop the ads.

RocFoamArmory

Active Member
Your process is pretty similar to mine. First I'll go over the foam a few times with the heat gun. You can see the texture change when it's hot enough. I'm then doing about 5 thin coats of Gloss Mod Podge on the foam. I spent about 12 dollars on a container, and it's more than enough for my whole Iron Man suit. I'm going to try doing a coat of Plastidip over the Mod Podge, as I've heard that helps as well. The Mod Podge is still fairly flexible, although I wouldn't try bending things very far. Check out my Mark39 build to see how the Mod Podge looks.
 

Snikt

Sr Member
How flexible do you need it to be? Xrobots.uk has a rad tutorial about using the eva layer, then coating it in smooth-ons 65D resin. Its still a little flexible but mostly rigid. I used the process on a project and it worked out great.
 

Don't want to see this ad? Sign up for anRPF Premium Membershiptoday. Support the community. Stop the ads.

Top