Foam topper for cargo trailer fold out bed conversion??

[wanabxtrm]

So I recently bought a snowmobile trailer I'm working on converting to a camper.

Here's some pic's and info/background from the cargo conversion forum.

viewtopic.php?f=42&t=60778

Long story short I'm looking at building either a canvas or rigid foldable (foam) topper for the front and rear ramps to make them into foldout beds. I've started reading the posts here and leaning toward the foam build.

2 questions early on: 1- when attaching the canvas on the exterior what are your using to glue it?? I saw reference to gripper and tb2 but don't know what either are. 2- anyone done something similar and have ideas on attaching the panel's. I'm thinking hinges on the foldable sections, and flashing with removal cotter pins to secure the sides to the top sections.

Cheers,
Alex

[GPW]

Alex, TB2 is Titebond II wood glue and is the recommended glue for canvas to foam ..

[wanabxtrm]

Just roll it out with a rubber roller I imagine?

[GPW]

Regular paint roller works fine , or brush it on .... We thin it slightly with water to make it spread easier ... Apply the glue , then the canvas over it , stretching (slightly) and smoothing with your hand as you go ... remember , canvas shrinks slightly as it dries , especially in the longwise length ... must allow a little for that ... Don’t skimp on the glue , it’s what holds the skin to the foam , and the skin provides the strength ... Once you get the canvas on , don’t add any more glue over that .... Primer and paint go on next ...

[mezmo]

Hi wanabxtrm,

A while back someone was trying to convert a "V=Nose" CT
into a combined Living Quarters and Cargo area:

"Converting a snowmobile trailer to an LQ/Toyhauler"
Here's the link:
http://tnttt.com/viewtopic.php?f=42&t=54167

On pg2 I have a couple posts [Posts on 01-22-13 and 01-24-13]
that may be relevant to what you want to do. Check them out.
Read the whole thread, as well.

Cheers,
Norm/mezmo

[wanabxtrm]

So I bought some foam to play around with and to insulate/fill my exhaust duct holes for my portable ac vent. (they exit through the 'fueling' port on the side of the trailer).

I've also laid out the sections needed to top the ramps. here's a quick snapshot:

Trailer.jpg (156.69 KiB) Viewed 912 times

So here's a few questions for you canvasing foam experts:

1- how much do you saturate the canvas when glueing w/ tight bond 2?

2- do you put the glue on the canvas and then adhere it to the foam or paint it on the foam and then place the canvas?

3- do you rough up the face of the foam? I removed the 'plastic' wrap on the face of it. Is it better to leave that (but then you are relying on its adhesion)

4-Joints/hinges/edges. Do you use anything to hold the edge of the canvas down ie- sandwich the edges in metal flashing etc? And has anyone done a 'canvas hinge'? I'm not sure how water proof it would be which is why I ask.

That should cover it for now,
Thanks,
Alex

[atahoekid]

So here's a few questions for you canvasing foam experts:

1- how much do you saturate the canvas when glueing w/ tight bond 2?

2- do you put the glue on the canvas and then adhere it to the foam or paint it on the foam and then place the canvas?

3- do you rough up the face of the foam? I removed the 'plastic' wrap on the face of it. Is it better to leave that (but then you are relying on its adhesion)

4-Joints/hinges/edges. Do you use anything to hold the edge of the canvas down ie- sandwich the edges in metal flashing etc? And has anyone done a 'canvas hinge'? I'm not sure how water proof it would be which is why I ask.

While I don't consider myself an expert, here's what worked for me.

1) I saturate the cloth all the through with the watered down TBII. By the way Gripper is a special primer by Glidden (since paint is essentially colored latex glue, it seems to work pretty well... at least for me)

2) I painted the foam heavily, then placed and heavily painted the canvas

3) Roughing up the foam helps give it teeth. Some people have poked thousands of tiny holes in the foam with a tool. Take off the plastic. It will eventually peel off on it's own anyway.

4) Some people use an additional layer of canvas to strengthen the corner, others have used metal flashing. I made foam caps (that's the blue corner caps). I don't know if someone has made a canvas hinge or not

Hope that helps. I know that it's long but reading that REALLY Long thread may answer some of your questions and give you some background on how we came to decide what works best... (There's brownie points in it for you if you can manage to read the whole thing )

[Mary C]

Alex I used a little foam roller to put the TBII on I covered the whole area and put it on so I could not read trough the glue I didn't put any on the material but went over the cut edges with the roller with extra glue. I started to do a canvas hinge but decided against it because I wanted water tight. You can glue on a couple of pieces wood where the hinge would be and use shower pvc for a hinge using metal plumbing tape to screw in the wood to hold the Pvc and then put canvas over that. See my pictures in my build thread Grits. I used a kitchen scraper to use to scrape along the canvas.

Mary C.

[KCStudly]

The canvas hinge has been done. IIRC it did not work very well because it was too flexible. The hatch wanted to slump down onto the roof and did not close cleanly due to the floppiness.

[rowerwet]

You only want a thin coat of glue in my experience, just enough to get a good bond, after it dries, fill the fabric with exterior house paint to seal the fabric. I use the oops paint for filling the fabric as it is cheap. Then paint it the color you want.
Some builders have had problems with bubbles under the fabric, I just found out recently that foam continues to outgass long after it is made, the outer skin of the foam traps some of this gas, glue solvents release it, perforating the foam before gluing gives a better bond and no bubbles.
I use a werner250 to perforate the surface.

[KCStudly]

Rower, Is there any precedent or specification for the length of time that this out gassing will continue or is this still just a speculation on someone's part? My roof and wall foam has been laying open for a good long time, over a year, and it would be nice to know that it is not a concern. So far I have no indication of any problem with my floor and bulkhead, which have been encapsulated in plywood skins for an equal amount of time.

Also, Big Mike's testing of the perforations, while somewhat subjective, seemed to indicate that there was no real strength advantage. IIRC, he observed that the little glue spikes that filled the perfs just snapped off at the top, and concluded that, since it did not increase the failed surface area any, it did not increase the bond significantly; so was not worth the extra effort and, presumably small amount of extra glue (at least that's how I remember it). (One could argue that the glue sticks to itself better than it sticks to the foam, or that the foam tensile strength is less than the glue tensile strength, so this small increase in surface area where it is glue to glue instead of glue to foam could arguably increase the bond strength, but I think the ratio of areas would be so skewed that the overall delta would be "in the weeds".)

I'm not trying to refute your findings. I'm just looking for any more perspective, from your own experience, that you can provide to help clarify the different conclusions. (Translation: I don't have one of those spikey wheels, and I don't want to bother with that step if I don't really need to. Plus, I have spent a great deal of time trying to eliminate flaws in my foam that might project thru the canvas, and it seems counter productive to risk chunking out pieces of it after all of that effort, so I need some pretty strong convincing to be converted. )

[lthomas987]

I sanded my foam with 80 grit sand paper until the shine was all gone.

I then used TiteBond2 cut with about 5% water which halves the viscosity according to the manufacturer and my experience. 5% of a whole gallon is 6.4oz (or half a beer can). Then rolled it on until there was a thin but solid covering over everything. I used a 1/4" nap roller. I then squished my fabric into it with my hands. When everything started sticking to my hands I squirted them down with water and kept stretching. I found having a squirt bottle (like a glass cleaner bottle) full of water was VERY helpful.

My experimentation didn't show that saturating the fabric with glue made it hold any better than this method. And it saved me a ton of glue. It may have cost me on the primer side because I still had to fill the fabric. But I went with two coats of Glidden Gripper for primer. The first coat SOAKED UP the primer, like a LOT of primer. The second coat didn't take nearly as much. I did the whole trailer inside and out with 2 gallons of glue and a bit over 2 gallons of primer.

[rowerwet]

KC, I'm sold on the spikey wheel for a different reason, in my own testing I glued an old sheet to foam using TB II and gripper, with smooth foam, and perforated foam. The sheet peeled off the foam with no problem with both glues. With the perforated foam the sheet tore and the rest stayed stuck, I couldn't tell that tbII was any stronger than gripper. Since tbII is heat setable I use it over gripper.
I read the out gassing comment just the other day in an article on duck works, the guy was building a boat with foam and got the info from a tech rep I believe.

Lt, I use the tbII straight and roll it on thin, that way it is tacky quickly. I found using vinyle gloves works the best for tbII, it seems to stick the least of any type of glove.

[KCStudly]

Thanks. I've done so much sanding, and have used a bunch of spackle, which is porous in itself, that there is nothing shiny about my walls. The 1-1/2 inch foam that I have used does not seem to have the plastic film. I'll have to look closer at the 3/4 stock that I have for the roof. My thought is that the thinner sizes have the film to help prevent damage in handling, while the thicker sizes don't need it.

I guess I will have to do a test on the spackle just to be sure. Maybe do my own comparison with partial spackle coverage, with and w/o poking.