laursand's Canvas over Plywood

[eaglesdare]

where is the floor wax discussed? i am reading it now, but its like reading our long thrifty thread. haven't found the floor wax yet.

[eaglesdare]

nevermind, found it. i think it starts on three pages before the end.
if that wax is cheaper than the minwax and works that would be wonderful. that minwax is expensive!

[GPW]

Those guys try Anything !!! But sometimes it works ... They do seem to have it down how to get a nice finish .... I guess the same would apply to us as well .

Floor wax , who would imagine ? You know that might make a nice clear coat on top of Latex paint ... a cheap clear coat on my little Foamie would really bring out the colors ... just guessing we’d apply it with a Sponge Mop...

[GPW]

It seems the more we use different glue (adhesive) products , some just work out better for certain gluing jobs. than others ..
Now thinking there’s no One glue for all Foamie applications , and we should try to select the right glue for the job ...
Maybe we need to all make up a chart indicating what glues are good for what jobs. Just a reference guide for the new folks ...

What we found : (Opinion)
For wood to wood construction such as flooring , braces etc. The Liquid Nails adhesive in the caulk tube does a really super job on bare wood , and the fit doesn’t have to be exactly perfect either. T2 works fine if the wood joins are close fitting ...

For wood to foam ... T2 works but dries slowly (good fit required) , or the Gripper , which dries slightly faster, but still needs to be a good fit ... Great Stuff, it sticks to anything , fit doesn’t have to be close but it is subject to expanding , shifting the whole surface edge slightly out of line ... usually requiring more great Stuff to fill the gap (personal experience )
Foam to foam ... All work , but T2 takes forever to dry , Gripper much faster , and Great Stuff just a few minutes... Great stuff will distort laminated foam panels unless they’re securely clamped , weighted , or bagged’ ...it keeps expanding ...
Foam to canvas... T2 for me ... (for the present job) , Gripper , both perfect ... Great Stuff , a definite "No No" trying to stick canvas down with that ...

Anybody else have some other glues or observations ? ... The more data we can collect on this in one place , the more everybody may benefit ...

[ghcoe]

I am finding I reach for the Great Stuff for most jobs. I find using packing tape keeps the foaming where you want it and keeps it from moving parts around, if applied properly for the job.

Gripper is still a bit tricky for some of the jobs. I find it works good for the sheet rock edging that I am using, but a bit skeptical on foam to foam.

Gorilla Glue works good for just about everything I use the Great Stuff for. I just do not like how hard it dries in case you need to sand. Great Stuff is faster drying and thriftier too.

[Wobbly Wheels]

For panel bonds with a large surface area, don't discount latex contact cement.
I've used it for foam-to-foam and foam-to-wood bonds with great results, despite some dismal results with it in the past.

I think I found the one thing it's good at !

[GPW]

Gosh, I forgot about the Gorilla glue ... but it’s just sooo expensive , it’s on the bottom of the list .. GS is much cheaper and works pretty much physically the same , slightly easier to sand ..easier to just cut it off with the requisite "Foamie’ tool “ (old serrated steak knife) ... more difficult with GG... IMHO... FWIW ?

[Wobbly Wheels]

If I've got the chemistry right, GS is essentially 'expanded GG'.
It's great at what it does, but I haven't used used much of it, personally. It took me most of a pint bottle to figure out that GS is indeed much more versatile. Were I building with wood, I would probably use more GG.

[GPW]

W2, we tried GG for building “other” (non trailer related) projects of wood , and preferred the T2 .. On several longbow builds we even had the GG actually fail in laminations, the glue separated ...T2 never did ... Just sayin’ ... It seems on wood projects we sometimes depend too much on the gap filling properties of the GG to make up for poor fitting wood joins... and the bigger the gaps , the weaker the joint ... Woodworking is a precise craft ...and not the easiest material to work with either ...

Foam is like Lego blocks compared to wood ... Much Easier to deal with ... Lighter too , and for trailer building ... Thriftier !!!

Really like how you can Zip panels together with the GS ... FAST !!! Like Super Glue for Foamies ... Saves a lot of “drying time “ and waiting ...

[Wobbly Wheels]

we even had the GG actually fail in laminations

Wow
For the glue itself to fail is definitely a dismal outcome after one spends the care and effort to shape the wood for the job. I just lammed a pair of curved window frames for the 'stargazer' windows for my trailer and I'd be choked if, after I spent all the time getting the jig set up and the mating surfaces trued, the glue let go after I unclamped it. You'd think PU would be an ideal glue for laminating. I used epoxy (even more 'ideal') but was considering GG - not so much from a need to fill gaps but from an overall strength perspective. My reasoning was that the expansion of the GG ought to increase the clamping force against the jig without starving the joint.
I don't have a temper, but I would probably want to throw something across the shop !

Agreed on the 'foamie glue' : I've been more than a little surprised by just how well the GS works as a glue.

Yesterday, I picked up a high density (beadboard) dock billet about 4X4X2, and I'm going back for the other two on Monday. Brand new and FREE on craigslist and the other two are big enough that I can only fit one of them into my Ranger at a time. She also has a truck cap she wants to get rid of, and it looks like the right size (going back to measure it up).
Score !!

The foam is destined to be a pontoon boat and it'll be GS joining them under a ply skin. I got to thinking about it after reading Sam's (desertmoose) great pontoon boat thread, though mine will be a bit bigger (12-14', fully decked, 18hp). The glue I use will be important because I want to minimize the weight of plywood skins, so I'll inset stringers into the foam which means I'll be joining the 'hot wire club" as well...but it all comes down to the glue. I figure that the GS meant for windows (limited expansion) ought to be ideal to fill the groove and clamp the stringer down till it does its thing.
Maybe some dowel 'pins' as well to add up some more surface area for gluing, but that'll be another thread.

[KCStudly]

First let me say that I have only used GS on on a industrial project (back filling a metal door jamb in a block wall) and to fill a minor hole on TPCE (when my drill bit punched thru the outside wall by accident), so I am no expert. But I have used GG a lot on TPCE. The GS is soft and spongy so it sands easily, but I would question its strength as a glue. Sure it sticks to everything, but having not tried it in a tight fitting joint, I am skeptical of its strength as a structural glue (hell, even GG says right on the bottle that it is not for structural joints... ).

Here's what I have done.

Tight fitting wood joints: TB2

Wood to foam recessed blocking: GG make sure you weigh it down or clamp good, be careful sanding flush as it does not sand as easy as extruded polystyrene foam.

Wood to foam recessed blocking (1 test): TB2, stuck good but did not fill slight voids.

Foam to Foam: GG, same comment, clamp well and sand carefully.

Laminating thin plywood to foam: 3M 30NF, undecided. It is expensive and I did not vacuum bag it. It took longer to set than indicated in my climate. Subsequent cut outs lead me to believe that it needs a uniform compression, as from efficient vacuum bagging, or a heavy roller that might not be compatible with foam.

Laminating plywood to foam: TB2 make sure that you apply very evenly with a roller (large globs or recessed puddles will not cure well). Apply a good uniform press as from an efficient vacuum bag. Consider using 2 shop vacs for large panels to improve vacuum capacity.

I have a high confidence level in the strength of my assemblies and the ultimate strength that I will achieve using these methods on TPCE, but being a hypercritical engineer I am always striving for improvements in materials and techniques.

I'll let you know what I think of the PL375 construction adhesive after I use it to glue my walls, floor, and bulkhead together.

[GPW]

Further experimentation with the Gripper indicates that BOTH surfaces to be joined should be lightly painted (Gripper ) before assembly ... especially when joining canvas to foam ...

[GPW]

From the FoamStream thread :

I feel compelled to report ... the more we use the Gripper , the more we like it as a PRIMER ... but NOT as a Glue for attaching canvas... Still some signs of skin lifting even after a careful application of the Gripper to both sides ... It could be the extremely thick canvas I’m using ... Haven’t tried it with a Thinner canvas .... Just sayin’ ...

I am waiting to see if the painted canvas shrinks in the heat , and magically re sticks itself down ... But we may have to inject some T2 under the bubbles to take care of the problem ... Thinking since we have the deep kerf slots still exposed , i could go in from inside the trailer and punch through the thin area between the kerfs to inject the glue .... no holes in the outside ...

[tonyj]

Having the same result with gripper on my non-trailer project. Most of the time it works, but lots of places (especially edges) have needed additional attenion and TB. My opinion is that Gripper can, by its naure, act as an adhesive--TB IS an adhesive!

Just to further the argument of using thinned TB instead of glue, my gripper cost $25-27 a gallon, the the TB cost $19 a gallon, and since i am thinning the TB 1/3 to 1/2 with water (and will NOT thin the gripper for this application), the TB is the most economical choice. I am coating the exterior of the canvas with thinned TB after applying to foam with thinned TB, and then applying gripper as a primer for the paint coat.

[GPW]

Ton’ , that does seem the best way to do it !!!