laursand's Canvas over Plywood

[OP827]

I want to add a few more comments:

1. GS I used was for windows gap fill, which could have a lower expansion ratio. Someone has mentioned on this forum that GS can further expand and distort glueup, but I did not experience that. I actually found quite opposite, there is practially no "spring back" once the part is glued up with this method and GS I used. One sample(or rather became one ) part is free sitting in my garage since Oct-2014 and hadn't change its shape at all.

2. It is important to have enough amount of GS into the groove, not to starve the glue in the joint. I think I might had not enough glue at one instance and just one kerf started to open back, but that could also be due to early unclamping. I fixed it quickly with small amount of TB2 and then clamped/clicked back for couple hours. It is quite easy to get deceived by the foam setting very quickly within minutes on the surface, while it takes perhaps a few hours for the GS glue to gain strength when inside kerfs. I'd just leave the clamps overnight and then it is a safe bet. Ambient temperature and humidity is a big factor too. It was dry and cool when this happened, may not be the case in humid and warm climate. GS needs air moisture to set.

3. Easier to remove packing tape when the glue is not completely solidified and still quite flexible, which happens on the sirface within 30 minutes. It is also good idea to spread the GS on the packing tape surface right after clamping - that way the tape and glue film comes off together more as one flexible piece.

[GPW]

Thanks !!! Every good tip is appreciated!

[ghcoe]

Another product that I have been using lately is Painter's Acrylic Latex Caulk by DAP. I glued two pieces of scrap foam together with it and I could not separate the two pieces a week later. I finally cut through the glued pieces and found that the center was not totally dried. I was able to pull the pieces apart at that point, but the edges where the caulk had dried gave at the foam not the glue line. I let the other piece dry another two weeks. I could not get those pieces to separate so again I cut that piece in two and found that in the last two weeks the caulk had dried all the way through. I have used it in some construction and like the results so far.

[OP827]

I have a question that I could not yet find the definitive answer in the BIG thread or otherwise on this forum via my google custom search here.

Did anyone actually did the foamie of plywood skinning with fiberglass cloth and Titebond 2 or other than epoxy or other resin stuff? Did that work for them ???

I checked polyester resin tensile strength properties and it is not that far from Titebond and in any case the fiber is always taking the stress first, the glue (what ever that is) is only holding the fiber against the stress direction to resist. I do not like epoxy fiberglassing the whole roof of my build due to cost and health considerations. I'd rather do with water based wood glue. Everyone talks canvas, but I already have a big 60yrd roll of 6oz fiberglass purchased for the build.

Titebond 2 tensile strength - 3750psi
Epoxy Tensile strength - 7000psi - ish
From structural perspective the fiber will take majority of the tensile stress applied locally to the laminate because of its much higher Modulus Young value.

Do you know anyone who actually did this?

Thanks for help!

[OP827]

TB3 impregnated Fiberglass cloth works for marine plywood and small boats, i found this - http://www.duckworksbbs.com/plans/simpson/T&G-Process.pdf

Did anyone actually do TiteBond 2 impregnated Fiberglass cloth skin on their trailer?

I find that fiberglass cloth could be economical when purchased wholesale in a roll and when its laminated with TB2 it gives a smoother that canvas finish, thus less paint and primer to use. Overall it could be a good choice..

[GPW]

“ Did anyone actually do TiteBond 2 impregnated Fiberglass cloth skin on their trailer?”
We used fiberglass tape with TB2 on the Foamie #1... Works Super!!!... Fiberglass cloth carefully applied , then painted over looks Nice ... and only a bit more expensive ... Just remember to wear your protective breathing mask .... don’t want to breath the fiberglass shards... ( WE used to do a lot of fiberglass work on cars (with resin ) ... sanding finishing is a laborious and nasty business (probably worse till T2 is completely cured) , why I chose just the Fabric with the “weave” (Good Hair) look ... At 50 feet away , you can’t really tell what the trailer’s made of , and most others don’t really care anyway , unless you tell em’ it’s made of Foam , then it becomes a “novelty” ... Like the time I was getting the license for the FoamStream and I told the inspecting State Trooper the trailer was made of Foam .... Instinctively , first thing he did was go up and beat on it ... everybody does that ... Why??? I don’t beat on others trailers ... unless of course they tell me it’s made of foam ...

[OP827]

“ Did anyone actually do TiteBond 2 impregnated Fiberglass cloth skin on their trailer?”
We used fiberglass tape with TB2 on the Foamie #1... Works Super!!!... Fiberglass cloth carefully applied , then painted over looks Nice ... and only a bit more expensive ... Just remember to wear your protective breathing mask .... don’t want to breath the fiberglass shards... ( WE used to do a lot of fiberglass work on cars (with resin ) ... sanding finishing is a laborious and nasty business (probably worse till T2 is completely cured) , why I chose just the Fabric with the “weave” (Good Hair) look ... At 50 feet away , you can’t really tell what the trailer’s made of , and most others don’t really care anyway , unless you tell em’ it’s made of Foam , then it becomes a “novelty” ... Like the time I was getting the license for the FoamStream and I told the inspecting State Trooper the trailer was made of Foam .... Instinctively , first thing he did was go up and beat on it ... everybody does that ... Why??? I don’t beat on others trailers ... unless of course they tell me it’s made of foam ...

"..Instinctively..", really? is that what foam does to people? Thanks GPW. I think the fiberglass cloth is not as bad until you have to sand it after it is glued. I should be careful not to mention the "f" word to spectators then , but it is still in my future, I need to build this "f" trailer first. I still wonder if someone actually covered the whole trailer in fiberglass and TB2 and what do they think of it..

And I made another foam sample with this. It is going to dry for a few days, before I do a destruction test.

[GPW]

Testing on a small scale is the only way to convince yourself of the merits of any particular material ... That’s become a standard practice around here...

Yes , for some reason , once I tell people the trailer is made of foam , they have to touch it ,knock on it, press it , or give it a bump to “test” the material for themselves... It’s as if they don’t believe it’s Foam ..

[OP827]

post deleted

[OP827]

OK, the destructive test of TB2+Fiberglass cloth on foam results are in. Here is the picture:



Observations: with the grooves, the bond was extremely strong, I thought I need plyers to pull the skin apart. The Cloth was tearing off to pieces too when it came off.

My conclusions: the way it separated in many places it clearly showed that the FG cloth is not getting impregrated as it would with Epoxy resin composite. Glass fibers do not get "wet" completely by TB2 thus NOT becoming an integral part of the laminate.
Therefore if FB cloth is being used I would rather stick to the traditional Epoxy laminate. Another question answered.
Cheers!

[GPW]

Thinned TB2 will wet the FG cloth ... JMHO, TB2 is too thick straight from the bottle ... we routinely thin it for different purposes ...

[Wobbly Wheels]

The glass will indeed wet out as shown between the starved area in the pic. It's a strictly mechanical process so I suspect it just just takes a little more "settin' time" like when you're wetting out a heavy Dynel with poly resin. Like GPW suggested, thinning the resin would likely help a lot. Those dry, starved areas are where any laminate falls down.
Using a peel test isn't necessarily the best way to measure a bond because you are testing only the very edge of the laminate. A better test would try to pull the whole laminate at once, like Gougeon does with their PATTI tests. I'm sure one could rig up a way to run a similar test. As long as the foam fails before the bond does (which is what I would expect to see), the test is a pass.

[OP827]

Pulling the whole skin at once is a better test I agree, but it requires special jigs etc. GPW is right the TB2 glue is much thicker out of the bottle than epoxy, epoxy is originaly designed for laminating with fiberglass cloth. My take on this is that these small glass fibers by their nature is not as good for wetting with water based glues as sticky and liquid epoxy sirup stuff. To make them wet with TB2 all through may require so much water that it will actually reduce the strength of TB2 and will require multiple coats which does not make the work more economical than original method with epoxy. My view on this that canvas fibers are naturally much more suitable for wetting with water based glue, while glass fibers are not as much. I feel that TB2 works best with canvas, it is like a natural thing to do.

I feel that fiberglass cloth wets best with epoxy, all fibers become invisible and transparent, it is ok to call me stuborn. Diluted TB2 and fiberglass(TB2+FB) will work for sure and it will be fine for a complete sock skin over a teardrop as in foamies, I just feel that I would need more rigidity, strength and sandability for my experimental foldable build than this TB2+FB material combination and technique offers. Although somewhat reluctantly, I would have to stick with epoxy for the combination with FB cloth.

I am having second thoughts now. May still do more testing in attempt to use TB2+FG inside for some partition walls and roof skin. I even think of TB2+canvas for inside - for a nice looking texture. I'll think of it when I get to that point.

[GPW]

“ that it will actually reduce the strength of TB2 “ .... logical but not quite applicable , only because even thinned TB2 will make a stronger bond than the Foam ... The foam always will fail first , not the glue ... Try wetting the fiberglass cloth with plain water before applying the glue , A common spray bottle will work ...

[Wolffarmer]

Would a bit of surfactant in the water. and/or the TB help?

Randy