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

3M specialty 78 is specifically made for polystyrene foam

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

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

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

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

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

Appreciate the test, thanks very much! Mike

Keep it up man, you’re doing great! Super informative!

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 .

Thanks for the testing. Helped my choice 😁👍🏽

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

Great video! This kind of stuff is what makes RU-vid such a valuable tool.

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

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.

Thanks for the video.

Good Review! Really appreciate.

thanks for sharing dude!

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.

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.

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

Hey just wondering how the foam skiff is working out and would really like to see some footage with how it handles. Great videos man👍

looks like the 90+foam can make a cool texturing for set design.

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.

I would've liked it if you also compared the 3M Foam Fast 74

Good video.

Awesome

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 .

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.

Try the "3M 78 Polystyrene Foam Insulation Spray Adhesive". I have just ordered some and I hope it works as advertised.

I’ve been thinking, how about drilling 1/4 inch holes so that the great stuff goes into the crevices and holds even better when it expands.

I know this is 3 years ago. I wish you had included the standard old white Styrofoam ( I think some people call it bead board). I'm wirking on a Rv storage bay door and need to glue the 1/16" filon fiberglass to the white Styrofoam. I know liquid nails Fuze*it will work but hoping to use a spray adhesive. Thanks for posting this.

I don't know a thing about it, but in another video I just saw a product called 3M Foam and Fabric 24 spray adhesive.

Hey Eric , just wondering if you could put some filler into the resin like mill fiber or micro balloons and it would give you more working time and not leave voids , yes you would have still clamp it to squeeze out the air voids but it might be cheaper than trying to bond stuff with the foam ? Did you try general propose resin ? Did it eat the foam ? Did you ever check on how to register a home made water craft yet as I want to put an outboard on one , This was a great idea it's light, unsinkable, strong if it's built right , ( cheap , as I don't have $20,000 for a flats skiff ) and you have the option of making it to fit you needs , Are you getting any orders to build them ?

Will the super 90, or any of these, melt the epoxy in fiberglass boat flooring that covers the plywood?

I tested also some glues, before building a styrofoam boat. And I tested after drying- in water (24h). Best result I had with "silicon acetate"-gel adhesive waterproof filler (using with gun)

out of these what would you say for spraying 2 tarps together is the best? Thanks

Will 3m 78 stick to an old fiberglass panel? Glue insulation to a truck fiberglass topper cap? Or should I use great stuff to glue panels to the cap?And fill gaps. I want to use some type of spray adhesive to stick fleece over the insulation. A carpet alternative.any suggestions on what to use?

So how would we hold layers of foam together using great stuff to build a boat? Plywood and weights?

Great stuff is a polyurethane foam.... equals toxic fumes with a hot knife. It would be worth experimenting with non foaming polyurethane glues... Thanks for your valuable work!

If I build a trimaran with your metod is it can be seaworthy?it can be stronger than plywood fibreglass?

Wonder if Oceangate used this to bond their titanium end caps to the carbon fiber tube...

Try 3m 78 It works like a cross between 3m 77 and great stuff

What is melting the foam is the propellant in the cans. It’s not the glue that eats the foam.

I would wonder if the Hreat Studd still dissolves the foam board, but then fills the created void with the structural benefit of the expanding foam.

Loctite PL3 Premium Get the large size for manly caulking gun.

You use the same epoxy you would if you were fiberglassing it I believe. That doesn’t eat the foamaway

Why not use tube silicone?

Soudal PRO 40P The best glue for this job.

Quick question on the Dow foam. Is this the regular uncoated stuff or is it the sound barrier plastic coated one? Thanks so much for this video!!

Contract cement in a can is a solivant

👍

should try using epoxy resin /

EPS or XPS?

Retest the gorilla glue spray

Epoxy?

One other issue with the Spray adhesives!!!! That glue will play hell with machining. The glue will melt and adhere to your machining bits, blades etc. The FOAM will not

You can’t use the gorilla for hair.

The Great Stuff is expanding foam. You can get past it by letting it expand before joining. I used it on my homemade pontoons.

The best is 3M 78...

Epoxy works better than any of these. It bonds so strongly that it’s impossible to detach it without destroying the foam.

cheap wood glue, hot glue, regular gorilla glue. Actually the RC model plane guys worked this out like 15 years ago. They also built full size planes with foam.

Im 0:03 into this video. And i see You are Missing 3M 78 Therefore, its not a good polystyrene foam-bonding video. Because that contact adhesive does not melt Polystyrene. And it creates a bond thats approximately the same strength and flexibility as the foam. You can barely just peel the foam blocks apart, after sing 3M 78, with some moderate damage to the foam. And it doesn't expand and push the foam apart like Great Stuff and Gorilla. But TBH none of these options are structural. If you need strength and longevity, use EPOXY and Glass Microbaloons.

You know if you call the given manufacturer of the foam they will tell you what works and just maby save you some $ and time.

Nope! 3M 78…made specifically for it. Loctite PL 300 if you have time to wait…

None of these are particularly good adhesives for XPS foam. Builders of foam and fiberglass airplanes like the Rutan Long EZ have been using a slurry of four parts epoxy to one part microballoons for this job for decades. Needless to say, they don't want their airplanes to come apart around them in the air...and they don't.