Dissimilar Veneer Thickness Double Platen

[vincent wawrzynski]

Hello All,

I have several different veneers that will combine together on a boat part using epoxy. I plan to use a top and bottom waxed platen to deal with the epoxy squeeze out. My problem is that one of the veneers is a few thousandths thinner than the rest. If I were using a breather layer I am sure I could just carefully sand the cured veneer. But since I am needing a top platen I don't know how the thinner pieces will end up floating.

Anyone dealt with this? Would wetting out some paper with epoxy as a shim for the underside of the thin pieces seem the right approach?



Thanks

[Dennis Jarchow]

I normally use a sheet of rubber between the veneer and the platen. This evens out any minor disparities in the veneer thickness, joints in the underlying substrate etc.

[John TenEyck]

Same here, I use a piece of silicone rubber sheet. It's 1/8" thick and has about 20% compression at 15 psi, IIRC, which gives you quite a lot of compliance to deal with veneer thickness differences. And being silicone, most glues don't stick to it. Also, I stopped using top cauls several years ago. I use a layer of sheet plastic and then a layer of heavy duty window screen as a breather on top. That allows the vacuum to reach everywhere and also self adjusts to any differences in veneer thickness on the top layer.

John

[Jeff Roltgen]

+1 for the "loose the platen" argument.


I use a layer of sheet plastic

I like to utilize 20 mil vinyl or polyurethane salvaged from old, failed vac bags. Otherwise, a trip to the fabric store gets you some vinyl, though it is a bit thinner.
Keeps breather mesh (or the screen) from being embossed onto the face of your veneer, levels out uneven veneers just fine, and sheds most veneer glues just fine. Considering the epoxy in this scenario, you may still want that wax paper layer for a disposable glue foil, if you are unable to round up the silicone sheeting.

I like the idea of the thicker rubber or silicone as a platen, but if it's just a few thou, I suspect it may not be necessary, especially if cost/sourcing is problematic. The bag, and relatively thicker salvaged bag material, have always offered plenty of compliance to handle any slight thickness variation when using multiple species of veneer, IME.


jeff

[Mike Henderson]

Put a sheet of plastic over the veneer and then put something that will "squeeze" over the plastic. I've used thick duck fabric, a yoga mat, and a few other things. Anything that will give a bit.

Of course, a sheet of rubber, as others suggested, will also work.

I haven't had any problems when using epoxy, but to be safe, you might use waxed paper instead of a plastic sheet. But you really don't want epoxy on the surface of your veneer (unless your veneer is thick enough that you can sand it off). It can show up under your finish.

Mike

[vincent wawrzynski]

Thanks all for the feedback