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I am looking for advise on best adhesive. I designed a product that requires glueing two layers of bamboo plywood. I am using generic yellow wood glue, dowels for alignment, and clamps but am getting separation. Anyone with thoughts on best glue/techniques?
Looks like your glueup may be the problem but no idea of scale.
Bamboo is grass, it is not wood, so the glue properties are not the same.
If it were wood, it appears you have cross grain construction. As said above, the lack of scale does not help get closer than answer.
What clamping pressure was used (psi or type of clamps)?
Lots of yellow glues - fresh, not ever frozen, type, brand, etc.
Do you have any experience in cross grain lamination?
thanks for comments and questions- the bamboo is 3/4 inch thickness and 3 ply. The height of this piece is 9 inches. It is a candle stick. In terms of clamping, I use 3 clamps, one on each end and one in the center. I do use dowels to align the two pieces.
I would make it in wood.
You may have noticed that bamboo has faded from the market. It was the golden child a few years ago, they couldn't grow it fast enough. Now it has faded. There are reasons for this that are beyond fashion.
As for working properties, it is not wood. Does not cut like wood, does not shape like wood and does not glue like wood.
I've looked into gluing plyboo before and the distributor said it's compatible with all different types of wood glues, although I can't speak from experience. It does move like wood, not sure how much in the different plywood configurations...linear, cross lamination & strand. The aesthetics of gluing the 3/4" 3 ply together may be part of your design, but they do make 1.5" thick slabs for counters (1.5"x30"x120") which would simplify the production of the pieces.
On the previous thread in this forum I asked about gluing dense, oily exotics with Titebond I and there may be similar characteristics. One of the responses recommended leaving the piece in the clamps a lot longer because the density of the wood impedes the moisture from leaving the glue joint so the curing time is lengthened. Bamboo is 2-3 times more dense than many domestic hardwoods and the glue joint failure could possibly be related to the adhesive not fully curing before the clamps are removed.
I would do two things: Go to the distributor from whom you buy the plywood and get the recommendations for adhesive and process from them.
If its not wood then why use a pva wood glue? Beyond wood its only good for paper and no load arts and crafts.
Try using epoxy resin. West System or the like.
Rough it up with 80 grit like David mentioned. That is typical for epoxy no matter the substrate.
When trying to restrain materials from movement, epoxy is the go to adhesive. Its got very good shear strength and sticks well to most things besides plastics.