Envirotex Lite resin on EVA and hard insulation foam (polystyrene?)

[Marthony]

Hello,

I'm checking to see what practice people here have had using Envirotex resin on EVA foam as a sealing layer (after heat-sealing). My reason for interest is to get a non-cracking flexible surface without need for ventilation.

I've used the product decades ago on wood, and know to breathe on it to burst bubbles in it as it sets. At the time I'd made thick coats of it, but for this application I imagine I'd want to do 1 thin coat, sand, 2nd thin coat, sand again, then proceed with painting routine.

Has anyone used this product in this way?

Thanks!

 

[collinE83]

Never worked with it, but it sounds very much like Parks Super Glaze.

http://youtu.be/VyDXs19aCm8

 

[Marthony]

Indeed, it does seem similar. She seems to describe S.G. as curing to a firmer state. Her application method is an interesting example; I wouldn't have thought of it.

 

[Marthony]

Just started experimenting with Envirotex Lite & Elmer's Clear school glue yesterday.

As of this morning, both pass the bend-without-cracking test, though the clear glue did allow the EVA foam to wrinkle underneath it. I plan to do a 2nd coat of clear glue before proceeding with the priming+painting stages.

With the Envirotex Lite, I added a small amount to the smooth side of the EVA foam and spread it with a foam brush (single-use per brush here) and it did self-level well, leaving the surface completely covered. I'll proceed to prime & paint with this single layer.

Any advice for automotive paints? Going with green, black & purple for final version.

 

[collinE83]

Cool! Any problems or tips with the application of it? and don't forget to post some pics when you get a chance.

 

[Marthony]

No problems so long as you read over the instructions carefully and always mix a bit longer than required. Having the resin within the right temperature range before starting sounds important. =)

With this I'd say you're looking at either a paint-on application or a flooding application; most references you'll see will refer to the latter. Any applicator, such a foam brush, may be considered one-use items - cleaning them may be more than these are worth. You have to put down cardboard etc. to protect all surfaces. The material self-levels, but that also means there are almost inevitable drips, to be caught in the first 40 minutes. And I expect when I get to complicated surfaces, that any amount will create some amount of pooling.

In my test I first heat-sealed the EVA foam with a heat gun. I then painted on some resin, and added a touch extra to cover bare spots. I swept over the piece with the heat gun on low afterwards to get rid of the little bubbles.

Here's a shot of the piece a day after the first coat: http://i1276.photobucket.com/albums...9-514C-4B54-A0A6-D7F0A87BC006_zpsslehbmad.jpg. Though it had appeared to cover the entire painted part and self-level very well, you can see small areas where it is technically covered, but doesn't have a perfectly smooth texture. For this reason I plan to do a 2nd coat tonight, also a paint-on. I found that a little went a long way with this method. (a flooding application implies that an amount will run off the edges, will self-level, and won't need a 2nd application.)

The instructions weren't explicit regarding how long to wait for a coat to set before a 2nd application; it notes a full gloss at 8 hours and full cure (at 70F) in 72. I'm going to try the 2nd coat at the 24hr mark.

I am hopeful that the 2nd coat does everything I need as my parts simply won't be floodable.

 

[Marthony]

Okay, we have some results!

For all tests, I applied a coat of paint-on white primer on half the test surface to see how it would look. No surfaces were sanded. I used two spray paints for variety of effect. I'll be using the glossy black, but will be sourcing purple & green metallic paints: http://i1276.photobucket.com/albums/y470/Martaxus/Test spray paints_zpsuxc5rdet.jpg

I finally have some insight on why people go with pure or diluted white/PVA/Weldbond glue: its all about getting adequate adhesion/sealing of the surface, a thick enough layer, yet not creating much ridges to correct later. =)

I created 3 surfaces with Weldbond glue: 3x pure coats + 2x diluted (30-50%, hard to be sure with such small volumes), 1x pure + 4x diluted, and 5x diluted. I think the ideal is likely a 2xp+3xd...will re-try. Here are the photos of each of the Weldbond white glue tests:
3x pure + 2x diluted: Good seal, but has texture from 3rd pure glue coat - http://i1276.photobucket.com/albums/y470/Martaxus/3x full w glue 2x diluted_zpsoif7un5d.jpg
1x pure + 4x diluted: Almost good enough seal, good smoothness: http://i1276.photobucket.com/albums/y470/Martaxus/1x full 4x d bubbled_zpsxjpvznf6.jpg
5x diluted. Texture of foam was still notable to touch. Not good enough of a seal: http://i1276.photobucket.com/albums/y470/Martaxus/5x diluted_zps2mhmtpnw.jpg

I found the Elmer's Clear glue at a larger Safeway store. I painted on 3 coats, which took much longer to dry than the white glue. I had hopes for this, but it did not accept the paints well and I feel it is the loser of the test, as I don't think the primer coat would remain flexible even if I wanted to use it: http://i1276.photobucket.com/albums/y470/Martaxus/Clear Elmer Glue 3x_zpslpfoswbc.jpg. It did pass the flexibility test well however!

Finally, the Envirotex Lite resin. I came at this differently than you would for the instructions, which favor a flooding application. Still, I did try that. The shapes I'll be working with don't make sense for flooding in general, but it was good for a test.
Flooded, single coat with primer: Remained slightly flexible: http://i1276.photobucket.com/albums/y470/Martaxus/Resin flooded_zpsnnditdrt.jpg
Foam-painted in 2 layers, 2nd coat at the 25hr mark: http://i1276.photobucket.com/albums/y470/Martaxus/Resin 2x painted_zps0wv1eyyh.jpg

I must say the finish of the resin is great. I wasn't sure the 2x paint-on method would work, and we'll see how it works with uneven surfaces - you are to catch any runs/drips within the first 40 minutes. On the down side, it is heavy and expensive.

In summary, I plan to further test the pure/diluted white glue and use it for non-flexing surfaces. I will use the resin for flexible surfaces and those that will take a beating, such as the lower legs of the system.

Any thoughts?

I haven't sanded cured white glue before - is it a simple matter?

Thanks!