Which glue for XPS to plywood?

[ghcoe]

Hi George,

I have watched all your videos, great informative stuff.

Actually I spent quite a long time planning and trying to make up my mind about going full foamie, woodie or hybrid. I'm confident foamies are durable enough for my usage, but as this was supposed to be a fun project for me and i like working with wood so this hybrid felt like the best option to me. This also gives me the benefit of getting to experiment with new stuff (XPS, PMF etc.) on this being my first build. I have a feeling this will be my learning project that will maybe someday be followed by a little bit bigger and fancier build.

And I found a suitable glue in my local harwarestore, a water based contact cement. It held up really nicely in my tests.

/KT

Thanks for watching my videos. You may find once you start working with foam that you will like it better than working with wood. I have done many wood projects myself, but once I started to work with foam ideas started to dance in my mind. So many things you can do with foam.

Good luck with your build! George.

[Noc3]

I've found the Gorilla Glue Construction adhesive, the cheaper white kind, doesn't like to stick to polyurethane finished wood and doesn't harden completely (at least not over several days) I can still easily scrape glue off of the poly with my fingernails. Admittedly, I didn't rough up the poly first but the adhesive is still too soft and gummy for my liking. I don't like picking gorilla boogers.

HOWEVER The gorilla Glue Max Clear is very strong stuff and bonds well to the un-sanded poly. I don't think it is paint-able though. It cures quickly to a MUCH harder durable plastic. Cost about 4$ more per tube.

I have not tried the "in between" GG Ultimate in the orange tube

My plan is to use a thick bead of construction adhesive on the outer edge of the floor to walls and use standard GG poly foaming adhesive on the interior side of the wall/floor joint. I think polyurethane will bond to polyurethane but I will lightly sand first for extra grab. My reasoning is the foaming adhesive is plenty strong and cheaper but the poly foam can take on water, so the construction adhesive is just for an exterior seal and the foaming adhesive can expand and ooze out into the interior side as it cures.

[tony.latham]

My plan is to use a thick bead of construction adhesive on the outer edge of the floor to walls and use standard GG poly foaming adhesive on the interior side of the wall/floor joint.

Two different types of glue in the same joint?

I'm just wondering if they are chemically compatible.

Tony

[Noc3]

Even if the two types aren't happy where they meet, they each have their own side of the joint to off gas to open air. The thin sliver of surface area where they meet seems inconsequential. The Construction adhesive also "works underwater" and is unaffected by moisture, so I don't think it will mind the other gorilla glue too much. I'll test before going big of course. On my way to return the standard strength GG const adhesive.

I wish we knew what kind of plastics these construction adhesives form when cured, and what solvents they contain. Some brands are more forthcoming about whats actually in their product but mostly its all just secret sauce.

[rowerwet]

I left the floor bare wood along the edges for the glue to stick, then drove nails up from the bottom to keep the foam walls in place while the gorilla glue cured. Other than the fabric skin there is nothing else holding my joints together. Thousands of miles later the teardrop is as secure as ever.
I also cut pockets into the foam walls for my roof spars, and glued them in with gorilla glue. They are still just as strong, years later

[gudmund]