Foam Boat Building: Best adhesive to use with polystyrene foam?

This is an adhesives test with 4 popular adhesives. I'm using XPS polystyrene foam from Dow (blue board) and Owens Corning (pink panther).

The pink foam is more spongy and softer and as such is not recommended for building boats.

The Dow Styrofoam brand blue polystyrene is by far a better product in my opinion for building foam core boats.

So which adhesive works better?

GREAT STUFF! Hands down it has the strongest adhesion and is the least expensive. All the other adhesives I used (Gorilla spary adhesive, 3M Super 77, and 3M High Strength 90 Contact Adhesive all melted BOTH the pink and blue foams to varying degrees.

All in all I'm using Great Stuff. It's messier to work with and MUST be clamped to hold it in place or it will create gaps between the foam layers.

Great Stuff is less expensive, and is more forgiving allowing great time to reposition foam pieces before clamping. When clamping large surfaces just use 2x6 boards and add some weight on top. Simple.

If you have any more questions or have an idea for a glue I haven't tried yet let me know down in the comments.

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Thank you!

[JerodMatlock]

I came with the questions and the internet came with answers thumbs up

[calebhelmuth]

3M specialty 78 is specifically made for polystyrene foam

[davidmiller]

Great video! This kind of stuff is what makes YouTube such a valuable tool.

[rubenvor]

This answered a lot of questions. Thanks for the test and sharing 👍🏼

[deankay]

I am building and shaping extruded polystyrene for door panels for use on my 54 years old truck. Once glued and shaped, the backside will be on Masonite or hardboard. This the door side but using a plastic water shield held to the door with traditional butyl roll tape. The front will have leather sewn onto 1/4” upholstery foam.
To cut the expanding (Good Stuff) or EPS, simply buy or make an adjustable hacksaw knife. They are sold at home improvement stores & Harbor Freight. Turn a screw to loosen and install a “Bi-Metal” hacksaw blade and adjust for length. I have EIFS on my house, adding R14 on the field, and R18 where 8” wide trim boards that look cottage like. It is “Exterior Insulation Finishing System” and a visit from western woodpeckers felt they could escape smoke & fire in the West and come to Nebraska. I grind around the holes for a taper, add expanding good stuff, flex the blade and hack flush with the finish. It is covered with treated fiberglass mesh & covered in concrete. Grinding smooth while on a ladder, I can spray the same finish to cover. The finish is a mixture of marble granuals and pigment w/ exterior latex resin & binders. It is used on commercial buildings from plazas to hotels. Rigid foam is cut into any shape while some use lasers for this industry. Design is no limit, as long a they can wrap it in fiberglass treated mesh, apply type “M” concrete and trowel or spray with a drywall ceiling texture gun & hopper. It is troweled with magnizium floats so no metal can rust however small. Type in “STO EIFS” in your search and yellow buckets w/tons of info.
Yes, hot wire works as we cut high density poly block with a wood frame, electric fence wire and a old arc welder. Once the 4 foot square block was marked, one tech on both sides & 3rd to flip the switch on, then off, depending on how hot is was. Just an idea. Enjoyed learning from your experience.
P.S. Get a gallon of acetone & tiny turkey baster sold in children’s section. But remove top of “Good Stuff” foam can, apply acetone to straw and 10 drop into the cans outlet. Compressed air helps but canned will help. Wipe with old rag but it allows you to reuse the can & straw over & over without waisting a half full can. Works every time, evaporates very fast and does not really need PPE if safety glasses, fan and near open garage door. On a scale of 1 - 10, 10 being real bad, it’s a 2, just barely. Best of luck!
Automotive ASE Master Tech since 1978 - Retired

[craigstephens]

Why did you use two 3M products that are not made for polystyrene? 3M 78 is specifically made for bonding polystyrene.

[Anthony-vhfu]

After watching this video I did my project with the great stuff and it worked fantastic . Thank you for your video I really appreciate it .

[outspokeninsider]

Thank you so much, this is exactly what I was looking for!

[PainterD]

Good to know before I get started on my project! Thanks!

[emcee]

Appreciate the test, thanks very much! Mike

[vincentb]

5 years ago, I went through this same process of finding the best adhesive for my van insulation. It was kinda by mistake I found great stuff as the clearly the best. I was using it to fill the gaps and noticed as the 3M was failing to stick to the van, the gaps were holding to the van and the sides of the foam, also noticed anything that got great stuff on it was impossible to clean off. So 5 1/2 years later the great stuff/ pink foam is still Stuck where it’s supposed to be. Warm Van.

[Traderhood]

Correct answer is Foam Fusion. Original Gorilla polyurethane Glue works well too. So does Epoxy. Anything with acetone in it will eat up the foam. If you want to use something with acetone, you must first prime the foam with water based acrylic paint.

[kismetbridgeforth]

Thank you, you saved me time and materials!!!

[joshriver]

Thank you! You just saved me a lot of hassle.
Super77 is no where to be found for some reason. I bought can of Gorilla few days back and was reluctant to use it. Decided to buy the Super90 and almost just used i. My project would've certainly failed.
Something funny..Ive used Great Stuff for years. Got a half dozen cans in the cabinet right now. I had no idea Great Stuff would work as an adhesive! I simply thought it was expanding foam to fill gaps.

[darkpassenger]

Thanks for the comparison. I almost used the 3M 90 then I read the active ingredients and it has acetone in it as the solvent (contact cement too). That stuff melts XPS and Styrofoam big time. I think I have a can of the Great Stuff in my storage shed.

[nathanhensn]

Thank you so much! People online were talking about different adhesives for styrofoam for RV's ceiling and 3M will definitely fail eventually due to erosion.

[murraymadness]

Epoxy glues foam very well and no expansion issues. But yeah to do a big sheet quickly, single-part polyurethane foam works well to fill gaps when glueing. Gorilla Glue (orignal) is same stuff.

[RickCatita]

Thank you for posting your results. this video is very helpful for my upcoming projects.

[troymiliona]

Thanks for the testing. Helped my choice 😁👍🏽

[lhackinen]

Tried similar test myself, Gorilla makes many glues, that spray in your test has solvents (fail) . Gorilla Glue Original is a similar Urethane glue to Great Stuff, but doesn't foam (as much) Both are moisture activated ( they don't need Oxygen, they need the water in the air to cure). I used it to bond 2 sheets of Xps .