3M 78 Polystyrene Foam Insulation Spray Adhesive, Translucent 17.9 Oz. Aerosol Can

Use: I do a lot of Halloween decorations using pink foam board (xps extrusion). In theory, one could use clear Gor—-a glue to stick pieces together, but I’ve never been able to get that to work. Pros: this stuff WORKS. Spray both flat side of each object, wait for it to get more tacky, then press flat sides together. The consistency is a more like rubber cement than superglue, but wear gloves!!! Really! Dry time varies. You’ll have at least 10-15 seconds to re-adjust, but once it sets, it’s all over. However, if you just have the spray on one piece, and don’t put anything to glue on it (like a board that extends past another) it takes awhile to dry. I would recommend spraying both surfaces. The nozzle has three “settings) and is a nice feature. The hole can get gummed up, but it’s easily peeled off by hand. If you’re going to paint, paint first, because it shows under spray paint, texture-wise, if you accidentally get it on paint areas. Cons: the price! Wow! I put off buying this because it’s so expensive, in my opinion. However, the can is huge. Far bigger than a can of spray paint. I haven’t finished the can yet, and I’ve sprayed about 60 square feet, double-sided. And quite frankly, it’s a time saver and it works. But if you were spraying two 4’ x 8’ foam boards fully, not just the borders…yikes. Full disclosure: I have no idea how this works regarding insulating a house. It’s not spray insulation, it’s glue, but again, I don’t know how it stands up if you’re insulating with foam boards.

I needed to bond layers of that "Pink Panther" extruded polystyrene (XPS) insulation foam board for a craft project. There are few good adhesives to use on this. Many solvent-based glues will dissolve it. Polystyrene is very non-polar (it loves organic solvents but repels water) which also makes water-based glues problematic for bonding sheets together. As a side note, you can effectively use water-based glues on the expanded polystyrene (EPS) type of foam, commonly called Styrofoam. EPS is the white white foam used for packaging, insulation, little foam airplanes, Styrofoam coolers, etc. Water-based glues can work on EPS because EPS is so porous that the water molecules can diffuse through it even though the polystyrene repels it. Not so with the pink XPS foamboard. If you try to bond two layers of XPS with wood glue, you'll find it never cures because the water molecules cannot diffuse through it in any reasonable amount of time. So 3M 78 to the rescue. 3M says this product is for the EPS type of foam, so I wasn't sure of its performance on XPS foam. I followed the directions, letting the adhesive dry on both surfaces for 3-5 minutes where it didn't look wet anymore, and then I put the two foam boards together. They bonded instantly (you only get one chance so get it right!) and then I put some weight on them and let them sit for a few hours. Like water-based glues, this spray adhesive cures by evaporation. However, the solvent molecules are not repelled by the polystyrene so they are able to diffuse out. I give it plenty of time to be sure. It worked well for me, no problems. Do use plenty of ventilation when using this product (take it seriously).

Works as claimed

Good product, but really, Amazon? Is this how we ship flammable aerosol? SMH y’all have really tanked it with the quality lately.

Works as advertized.