LOSP H3 pine

[tony.latham]

Why not a PVA wood glue such as Titebond? I went through two gallons of it on this last build.



Tony

[edgeau]

Why not a PVA wood glue such as Titebond? I went through two gallons of it on this last build.



Tony

When I cut into a void doing my windows the only glue that would hold the ply back together was the Sika polyurethane. I tried PVA and construction adhesive - both failed. So this stuff is now my go to wherever I know I need strength.

I always wear gloves using it though as it has a warning on the bottle that it "may cause cancer"

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[MickinOz]

Why not a PVA wood glue such as Titebond? I went through two gallons of it on this last build.



Tony

I went with what I could get locally.


P.S. How did you use 2 whole gallons?

[tony.latham]

P.S. How did you use 2 whole gallons?

I glued a lotta wood together...

I built sandwiched walls and used TB3 to glue the interior/exterior sheats on. That's where a lot of it went. Additionally, I built a Fredrick's style hatch that requires two additional pieces of ply in the galley. Lots more glue.

Tony

[MickinOz]

So I cut another 90mm piece off my 2.1m stick of 90 x 35 LOSP H3 Pine.
I glued that face to face back on the end of the long stick, clamped it lightly, and left it for about 20 hours.

Face glued 90mm x 90mm.JPG (49.84 KiB) Viewed 3205 times

Then, I needed to test the joint.
This time I clamped the 90 x 90 block in my bench vise.
This left about 2m of 90 x 35 pine poking out into the room.
So I hooked up a scale to the other end of my 2m stick, and got my son to pull on it while I filmed with my phone.
Here is what happened.

https://www.youtube.com/watch?v=3E5qHfq6HJQ

Round off 2m to 6 feet.
60 lbs of pull at 6 feet = 360 ft.lbs I reckon. I love this Sikabond TechGrip

[tony.latham]

Then, I needed to test the joint.

What I see in your photo is that the glue failed before a small portion of the wood failed. If you try the same experiment with a PVA glue, the wood will fail before the glue fails.



Are you sure PVA glue isn't sold locally? That stuff is everywhere here. Usually sold under the Titebond or Elmer's brand names. Hardware stores, lumberyards, and of course the big-box stores. It's thee go-to-glue over here for woodworkers.



And it's cheap.

Tony

[MickinOz]

Of course PVA glue is sold locally.
Titebond Water Resistant PVA glue is not.

Bear in mind I am applying a twisting force in the plane of the faces, not lifting it to pull the two surfaces apart.
i.e. I'm really testing the shear strength of the joint, pulling the grain sideways rather than lifting it out of the timber.
I sincerely doubt the PVA that I can walk into the local hardware store and buy would take 360 ft.lbs of twisting at 20 hours old.
Anyway, it is not really about which glue takes the most to break.
It is a case of these are the waterproof glue and outdoor grade timber that I can buy locally to build the floor frame, but are they compatible?
Will the glue adhere to the oily surface of the timber?
Answer is yes, and you really have to lay on that joint with a 6 foot lever to crack it.
BTW, the PDS for Titebond 11 says it's not for structural or load bearing applications, and warns that it should be tested for adhesion if you want to use it on treated timbers, and that you should contact the technical team if you want to use it on oily timbers.
The link doesn't work for me.