Old brown glue strength?

[Aaron Rosenthal]

I’ve been building a podium of oak plywood edge joined to oak strips to form the 90 deg. corners.
For the glue I’ve been using Old Brown Glue; mainly, because as I noticed a mistake I could heat it and rejoin the pieces once the error was corrected.
Today through a stupid error on my part, the completed case fell from the assembly table to the floor, and the edge joined assemblies split apart.
I’ve never had this happen before (joints coming apart, even when abused) when using yellow glues.
So my questions are;
- is OBG not suitable for plywood/solid wood joinery, or,
- perhaps the strength of OBG is not the same as yellow glue;
- make a lower assembly table. As it is, I’m too crowded in my little shop.
I refluxed everything back together, but the public wants to know ……

[John RStegall]

I would contact the seller. Patrick seems to be a straight shooter. It probably has a shorter shelf life than yellow glue but that seems extreme to fall apart like that.

[chuck van dyck]

In my experience it is strong enough. Its not as strong as yellow but has other advantages. I use it because I can get it everywhere and it easily washes off.

Can you describe the joinery a bit more? Also, did you apply it to both surfaces?
How long was it in the clamps?

I don’t think I’d use it on plywood. Sizing the plywood edge first would probably help. Plywood is thirsty.

[Jeff Roltgen]

I could heat it and rejoin the pieces once the error was corrected.

This should be regarded as a significant contributor to failure, if done repeatedly. Any manipulation of the glue-line beyond the initial clamp and set process greatly reduces long-term performance, regardless the glue you're using. Betting the manufacturer would conclude similarly.

And yes, a shorter assembly table may be in order! ;)

jeff

[Robert LaPlaca]

Aaron, hide glue creates a rigid glue line, in fact it’s an easy way to remove glue blocks with hide, by giving them a quick blow with a hammer. I find I get a gentler broken glue line with hide, generally some surface fibers and it’s easy to fix, just add more glue and clamp, no removing of the old glue is necessary.

As Jeff mentioned, once the glue starts to gel, the glue line shouldn’t be disturbed, think of using hide glue like soldering copper pipes.

[Mel Fulks]

Hide glue and Old brown Glue are not the same thing. Certainly possible that they have some of the same stuff. Old time hide glue flakes or
granules can be
bought in different strengths. Some just buy the strong stuff and water it down to make it “reversible “ with a tap o’ the mallet.

[Mike Henderson]

I think I read somewhere that hide glue does not have a lot of tensile strength. It has good shear strength, which is what you need for something like a mortise and tenon joint.

Mike

[Aaron Rosenthal]

Thank you all for your replies.
I did contact Patrick and he gave me one tip which I believe may have been part of the issue; I was using the OBG directly without heating it, as it was warm enough in my workshop that the glue just flowed.
It appears according to his reply, that for optimal strength, it needs to be heated to 140 deg F., which it certainly was not in my case.
Anyway, I've followed instructions and re-glued, clamped and cleaned everything, and the build progresses.