Teardrops n Tiny Travel Trailers

Being as it appears that I can only get 1" xps anywhere near me, I'm thinking I'll just go with that and face glue them together.
I've done a lot of research and know that foam fusion and Tb2 should both work, but $ wise I want to use TB2. I've seen the results in videos of small samples being face glued. My only concern is if in the middle of the sheets is it going to dry and cure ok? Will I need longer cure time?
I will be prepping the sheets by sanding the surface and perforating and will be doing PMF both interior and exterior of the final doubled up panels.
I'm actually thinking now that possibly only finding 1" is a blessing in disguise as it will be easy to just rip 1" thick wood to use anywhere I need it and plan out the layers, instead of having to cut or route out channels in 2" for wood. I will only be using wood around the perimeter of the base, around windows and doors, and some roof spars.

You'd best experiment..

When I tried to glue the foam together with TB2 I took more than
2 days to cure. I used Gorilla Glue. I was not trying to do large
surface areas. Gorilla Glue requires a method of clamping.

I cut shallow kerfs to act like chimneys or vent ducts, so adhesive would dry. Then I had to plug all of the ends of the kerfs by sticking little pieces of foam into each slot, about a half inch long or so. Somewhat tedious. If I had it to do over I would have just kerf bent 2 inch thk foam.

... or just use thickened epoxy.

I wouldn't use a water-based glue. They take forever to dry. Literal YEARS, if you glue 4x8 sheets together - possibly never actually fully drying, if then sandwiched in a wall or encapsulated in PMF.

In hobbies that use XPS for building scenery, models, etc., Gorilla Glue (or other expanding polyurethane glues) is the go-to.
However, it requires sanding and cleaning the surfaces for a proper bond. And large glue-ups may see some bowing in the middle of the sheet(s).

Without sanding, Great Stuff will give a stronger bond, but it requires a notable amount of weight and/or clamping to keep large pieces from bowing due to the foam's expansion. And, of course, it will be messy.

Personally, I would just use Super 77 spray adhesive.
I use it for a number of other applications - most of them non-automotive, even though it is meant to be an automotive headliner and upholstery adhesive.
It is safe on most foam, including known brands of XPS, is easy to use, and doesn't take forever to set or dry.
As long as you let it tack properly before 'bonding', there isn't really any time lost to curing or drying afterward. Just spray, tack, stick it, and get on with life/work.

In the aircraft building world (using moldless construction) epoxy is used. But you'd have to have your ducks in a row for gluing two complete sheets.



Tony

Regardless of which product is used, remember that nothing will be as soft as the foam, so consider that if there is any sanding to do at the joint after the glue up. No matter how delicately you sand the harder glue line will press down, and you will sand more of the foam than the glue.

3M 100NF contact adhesive is what I've seen used.

This I have tested fair sized pieces, but cost comes to play.

I am playing with vinyl floor glue. Good results so far.

ghcoe wrote:I am playing with vinyl floor glue. Good results so far.

Interesting, I happen to have some of that on hand and never thought to try it, its fairly cheap,, mayhaps a little experimenting is in order here! Did you sand and/or perforate first? Glue both sides? If my thoughts aren't wrong I do believe that is chemical dry/cure and not air dry/cure. And, decent open working time too!

KCStudly wrote:... or just use thickened epoxy.

I have some epoxy on hand, tried it, somewhat melted the foam and left voids, not an option at all, maybe just wrong epoxy, I don't know, just tried what I had on hand.

I have some epoxy on hand, tried it, somewhat melted the foam and left voids, not an option at all, maybe just wrong epoxy, I don't know, just tried what I had on hand.

That's exactly what polyester resin does. It has styrene in it. You add a few drops or a squirt of catalyst to get it to go off. Does that sound right?



Epoxy is mixed 1:1 or 2:1. It doesn't dissolve foam board.

Tony

QueticoBill wrote:3M 100NF contact adhesive is what I've seen used.

yup, works great . . . once pressed together you'll never get them apart.

msaxton63 wrote:

ghcoe wrote:I am playing with vinyl floor glue. Good results so far.

Interesting, I happen to have some of that on hand and never thought to try it, its fairly cheap,, mayhaps a little experimenting is in order here! Did you sand and/or perforate first? Glue both sides? If my thoughts aren't wrong I do believe that is chemical dry/cure and not air dry/cure. And, decent open working time too!

I did sand and wipe off with alcohol before doing the test.

That was my thoughts that it did not need air to cure. The next day it was a sold piece. I even cut it to see how the cure was in the middle. It was cured. I tried to pull the two pieces apart and the foam broke before the glue line. I think I am satisfied with the results of bonding. I did not use a trowel to apply the glue, but I think that if applying to larger pieces I would apply with a trowel.