Need help laminating plywood

[Louis Brandt]

Hello,
I have a “laminating” question. I need to laminate two pieces of 1/4 inch exterior mahogany plywood together. One piece will be 24 inches by 48 inches, and on top of that, I want to laminate a slightly smaller piece, about 22 inches by 46 inches. The smaller piece will be centered on the larger piece. The question is, should I use glue, panel adhesive or even contact cement? I don’t want to nail or screw these pieces together. I also don’t want to have to clamp them together during the process, since the clamps would have to extend so far into the middle in order to achieve a tight connection. I would prefer to just put heavy weights on the apparatus until it dries. When this is finished, it will be used in a garage, so there will be humidity and weather fluctuations. So, what does anyone recommend: glue, panel adhesive or contact cement, or something else?
Thanks,
Louis

[Lee Koepke]

I would think an 'exterior' PVA glue would work fine.

You could use some cauls with clamps to hold it down. If it has to be perfectly centered, use some 1/4" "spacers" to get the top piece correctly positioned, and clamp your cauls across to get even pressure. If your cauls are slightly convex, the pressure should end up applied evenly across the piece.

[Ben Grunow]

Epoxy is the answer for exterior if you dont ever want to worry about it.

I fiind that laminating plywood works well with any glue and usually the plywood laminations will come apart before the glue joint.

[Art Mann]

My first thought was epoxy also. The way it is commonly done in boat building applications is to mix wood flour (sanding dust) in with the epoxy and then spread it on with a trowel like is used with vinyl floor adhesive. The texts on the subject say to make the epoxy and wood flour mix about the consistency of peanut butter or a little thinner. I would not use straight epoxy as it will soak into the wood too much and starve the bond. After applying the glue and placing the pieces together, I would use heavy objects like boxes of tools or sand bags to keep the assembly flat. If I were going to use PVA, I would try to clamp the pieces together more so than using epoxy.

[Jamie Buxton]

A vacuum press is the best tool for your job. Post where you are, and maybe another SMC member with a press would help you out.

[Jim Solomon]

Titebond III. You will have to nail in two #18 brads about 3/16" and nip them off leaving about 1/16" to grab the upper piece to keep it from sliding around. I would temp. place the upper part on and apply painters tape around the parimeter to control glue squeeze out. Roll on the glue pound in the brads, tap the upper part with a block of wood for a backer to seat it on the brads, then clamp using cement blocks if you prefer that way or by using cauls as stated. I had some leftover 1/2" ply that I laminated together with Titebond II and made shelves out of them in my outdoor garden shed. Going on three years they are still together. My weather ranges from, at the moment 7 degrees to high 90's. With the same swing in humidity.
Jim