Adhesives for Foam

gmff

Member
We are building some foam stone walls. I want to permanently adhere the foam to the plywood, any suggestion for an adhesive. I have a couple of buckets of cove base adhesive and was thinking of that but would like to know what others use. Thanks
 
30NF is, in my opinion, the best way to go. If you use Liquid Nails you have to use the type rated for foam or it won't cure and will just eat the back of the foam.

If your cove-base adhesive is the Latex based type it may work. The big question is: is the substrate porous enough to promote curing of the product.
30NF is essentially a Latex based Contact adhesive. You let it cure on each face prior to assembly. Once you stick 'em together, they are stuck.
 
I see this question discussed in great detail on another site. While it seems the 3M 30NF seems like the right choice, lots of folks don't like it. The water based liquid nails type product seems most preferred. Cut large tubes and trowel on with notched trowel. Gorilla brand seems popular or one other I can't recall name of. Some folks claim great success with titebond but secret seems to be a thin rolled on coat and roughing up the foam so no thick puddles. Orchestra shell builders use to mist foam with acetone to add texture but a wallpaper scarifier seems popular. Gorilla glue also has proponents, but may need to mist ply with water. Some folks kerf the foam to allow drying.

The contact cement seems logical but this group who glue a lot of foam and post on it daily definitely shuns it. Tnttt.com
 
I came here to say 30NF but also want to throw in Sta-Put.

I've seen a lot of guys use Gorilla glue, but you have to clamp it or screw it also.

Loctite PL300 Foam Board is another popular option.
 
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Standard contact cement is not usable at all. Part of my choice for a Foam adhesive comes down to how/what you are using the end product for. I like 30nf beacuase if you are sculpting, it doesn't tend to gum-up on the seams in the same way Liquid nails does. Gorilla glue, being a Polyurethane, needs water to cure. It was mentioned that you need to mist the substrate prior to adhering the surfaces but you cannot, dependably, do that between layers of foam. Gorilla glue expands as it cures; it also has a much crustier foam texture than Extruded Poly or expanded poly, which is to say, it screws with your seams again. I've also seen Gorilla do the "eat into the foam" thing which doesn't makes sense to me but I'll have to review the chemistry again.
 
Its odd that within two different communities - in this case for me the theatre community and the teardrop community - there is such a different consensus (consensi??) Scenery shops and the folks that build (or use to) orchestra shells and platforms with foam and plywood strongly recommend water based contact cement - like the 3M 30NF. The tear drop builders and other trailer builders do not like 30NF and use any number of other products - successfully. I can't reconcile the difference and don't think either side is wrong or guilty of other than good workmanship.

I do worry about the expansion of the moisture cured polyurethanes like Gorilla Glue and how to compensate for that. Good bond though.
 
Liquid nails (or other brand) is my choice to glue foam to the base material. a little trick I learned is glue on, place foam on then remove foam for a couple of seconds and then reapply the foam. This lets Air get in to the glue and starts the curing process.
Regards
Crispy
 
At the risk of being shot for my blasphemy, I've had the regrettable experience of having nothing but a hot glue gun to affix foam to a surface.

I'm sure you can figure out why that's a bad idea.

If you absolutely have to though, make sure it's either a low-temperature gun, or on a dimmer ;P

"Hey, the foam is melting! Can I get channel 35 to 30% please?"
 
We've had very good luck using the canned spray foam (Great stuff spray foam). If you spray either surface with the spray foam and then put the 2 surfaces together and weight the connected surfaces (to avoid the foam expanding) you'll get a strong bond in a short amount of time.
 
depending on the size of your stones and the size of the wall I keep a shelf stocked with the 3m super 77/88/90 (surface dependent) for aerosol and quick/small jobs, and a +1 for the standard "green glue" 30NF. Invest in the 5 gallon bucket and you'll be ready to go. There are some things companies simply get right and 3M got contact adhesives right.
 
We tested out a product in grad school called simalfa. Wrote part of my thesis on it. It requires a lot more infrastructure than your average 30nf, but man is it great and fast!

It's expensive, but not much more than 30nf. Gravity feed hose to a pneumatic sprayer, spray only one side for good contact, both sides for a near unbreakable bond. Is the Best way to go, but you can roll or brush it on like 30nf. Best part is, put it together after 10 seconds. That's right seconds. Not lay it on and come back 20 minutes later like you do with the 3m "green glue" just to recoat so you know it will hold.

Obviously, there are some drawbacks. You need a smarter, more diligent end user for proper set up and clean up if your going to spray. If you don't dial in correctly, overspray can be an issue. And you'll want to mask off the extra area. Otherwise plan on replacing the floor or decking over it because it stays sticky. If you usr it like 30nf, then it functions identically, with far less wait time.

Shelf life is less than 3m, I think it's 4 months, vs 3m's 12 months, but it also is a smaller volume than 5 gals. Just as susceptible to problems if its freezing out as 3m, so order before it gets cold if you're in the north.

Also water soluble and GREENGUARD Gold Certified

If you've got a ton of foam to wood to do, it's worth the extra hassle with the amount of time you save in dry time alone.

https://www.simalfa.com/products/321
 
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