"Best glue for XPS foam?" Topic

Just wondering what would be the best glue to bond pieces of XPS foam(the pink stuff) together?

I would use PVA.

I use Elmers white PVA glue. Gives a nice strong bond.

Elmers here as well.

I also "paint" it with Elmers to keep the pink of the foam from bleeding through the final color.

To keep the edges of foam hills from chipping, I paint the edges on both sides with Mod Podge. Elmers or PVA glues would work as well

I sand it lightly and use Titebond Carpenter's glue (the yellow stuff) use it one all my projects, holds like a bear-trap

To cover the surface I use a mixture of Elmers glue, Brown wall paint, Model railroad ballast for texture and water to get the consistency,

William Warner +1

Well that was quick! Thanks guys. I figured plain old PVA glue would be sufficient but I figured I might as well get confirmation from those who've used it successfully.

As for protecting them I use a good thick coat of ModPodge and paint them with the same color house paint I painted my table.

And as a side note, the hills I currently use were kindly made for me by Anton, for free, a couple of years back. Thanks again Anton.

Sorry, but I beg to differ.

White glue needs air to dry, so if pressed between the foam boards, it will not do so.

There are other, better glues to use, but they currently escape me right now. Sorry.

Some are specialty glues which are quite expensive – spray-on, if I recall correctly.

I've seen them mentioned on various Facebook groups, and suspect there is info just posted online too, like on Youtube videos.

PS foam is not a great a moisture barrier, especially at 1.0" which is the most common thickness that I use. So PVA glue normally does the trick for me. Admittedly it does take I while to dry. I normally leave it for 24 hours to set before I cut it up.

For really large pieces or if using thicknesses > 1.0", it may be worth looking for a more specialist glue. For smaller pieces and if using 1.0" sheets I would stay with PVA to keep the cost down. It is not as if I am making anything too structural where failure would be a major issue.

Tackyglue hold the best that I have seen.

Thresher, that's a good point. I now seem to recall an old youtube hobby video that mentioned something about that.

Hopefully Martyn K is right about PVA being effective for 1" XPS as that is what I'm gluing together: two 1" pieces to make a 2" hill. Fortunately there is no rush so I'll have plenty of time to let it dry.

3M Super 78 or Super 77 (not available in all states, IIRC), as well as some others:

gluetips.com/glue-for-foam

link

Some are better than others, and some are difficult if not impossible to cut with a hot-wire cutter once dried.

Check out other Youtube or FB foam postings for more details on that.

I prefer 3M Spray Adhesive for Styrofoam. It sprays on in kind of a stringy stream with almost no overspray. I lay out old newspaper or craft paper to catch overspray (mostly me spraying beyond the edge of the foam). Spray both foam surfaces, let them set a few minutes, when the adhesive is aggressively tacky and not liquidy any more, align the pieces and press together, done.

I have pieces that were sprayed 23 years ago, and are still holding fine.

Well I do have some 3M GP 45 that might be good. Maybe I'll have a glue-off between that and the PVA to see which one is better…

Super 77 used to be fantastic for this, but some years ago (maybe 1998ish), they changed the solvent in it, and it would attack/react with the foam. It will work with some foams, but it attacks etruded pink, blue, and grey-green insulation board the last time I tested it, which was about three years ago. So unless they've changed the composition of it more recently, I would be carefull about the Super 77.

UHU POR is designed for XPS foam and is fantastic.

I second the comments about PVA. Its fine for small pieces, but anything over an inch and the glue in the centre won't cure, especially if the surfaces are previously treated with PVA. I have seen terrain that is DECADES old broken up and the PVA was still wet inside (and it stank).

G.

Thanks for all the input guys. I think I'm going to test out the PVA and 3M GP45 and see which works better, because it requires no further cash outlay as I already have both.

Coming from a sculpture background, one of our intro to 3D projects involved gluing together pink foam, carving it, and them covering it with plaster. We always used rubber cement to glue the foam together. Apply it to both surfaces, allow to dry, and then press the surfaces together. Incredibly strong bond that allowed us to go to town with rasps and chisels and knives to carve the blocks up.

I would be cautious with spray adhesives unless they are designed for foam. The propellent can cause foam to 'melt'.

I cover foam surfaces with PVA and sand to strengthen them. 3 or more coats and it is rock solid.

I've used Elmers and its held for decades, no problem setting at all.

Toothpicks, strategically placed, are sometimes used to provide additional structural integrity.

That helps eliminate sheering.

I used Liquid Nails on a recent island I made out of pink foam, and it seems to work just fine.

The Terrain Tutor always uses PVA between foam, however he makes sure to either dot it or use squiggly lines where air can get between there. Then he also seals etc when that step is complete.

I use Gorilla Glue Heavy Duty Construction Adhesive. Comes in the tubes like caulk.

Well I tested both the 3M GP45 and PVA(Elmer's spray glue) and they both held strong. I gave them 24hrs to dry and they stayed together in spite of my best efforts to pull them apart.

So I chose to use the Elmer's spray and it worked quite nicely and I now have some nice 2" hills. Thanks for all the input.