Veneer Question

[Lee Schierer]

I've never used thin veneer for anything. A friend at work wants to use a piece of paper backed mahogany veneer to make a work surface for his fly tying. What is the best glue and method to attach this veneer to a plywood substrate. We will also be banding the edges. The work surface is to be 24 X 36.

I don't think we have access to a vacuum pump! But if I did what vacuum level would I need to get down to?

[Alan Turner]

Lee,
My vacuum pump takes my bag down to about 25, I think. I also have never used any thin veneers, so can't hrelp with glue issue.
Alan

[Don Abele]

Lee, the press I use can go to down to 35 inches, much more than I would ever need. I personally like to use Unibond 800 for veneers, regardless of thickness. This is a 2-part urea resin glue. It creates a very rigid bond to prevent "creep" - movement of the veneers during changes in temp/humidity. Veneering without a press can be tricky. If the veneer doesn't completely bond, it'll bubble and when used the veneer will crack/split. You could try setting the substrate on your bench, sandwiching the veneer between it (with glue in between) and another piece of plywood over it. Then place heavy cinder blocks along the entire surface. If you use solid blocks it'll exert a fair amount of force and may work. Can't testify to this, just a thought I had that might work.

EDIT: Oooppss...I didn't answer your question. You need a vacuum that can pull down to about 20 inches - that exerts somewhere around 1280 pounds per square inch. A heck of a lot more than those cinder blocks could, but I can't think of anything else you could put on top. Oh, and just in case the thought crosses your mind - you can't use your car. Each tire only exerts 1/4 the weight of the car and puts it all in the area of contact (about 4x6)- it's not spread out enough for your project.

Be well,

Doc

[Steve Jenkins]

Just to nit pic a bit. 20 inches of vacumn equals just under 10 pounds per sq inch. It comes out to 1415 pounds per square foot. A standard atmosphere is 29.921 inches of mercury or 14.7 psi which is the most pressure you can get by pulling a vacumn.
20" is enough pressure if you are doing a flat panel and you use a piece of mdf or particle board for a caul. Steve

[Don Abele]

Ooopppsss...Steve, that was a typo on my part - it should have read:

"You need a vacuum that can pull down to about 20 inches - that exerts somewhere around 1280 pounds per square foot."

The 1280 is wrong because I didn't check it - I cut and pasted it from a veneering web site - go figure. You're right, it should be 1415.

I understand the most you can draw is a single atmosphere of vacuum at sea level, but if I dead head my pump, the gauge quickly maxes out at 35 inches. Not sure why/how. My system uses a venturi based vacuum.

Sorry for any confusion.

Be well,

Doc

[Roger Barga]

I agree with using unibond 800 - it's the best glue for the job. however, if you are only going to do one project and it's a small panel - then either hide glue or yellow PVA glue will suffice. Now, I'm reading between the lines here but if your friend is building a fly tying table (typically 18" x 24") then you should be able to glue up a project (panel) of this size using clamps (albiet a rather large number of clamps, but easier to get your hands on than a vacpress). The key is to get pressure into the center of the panel. Let us (me) know if this is something you wish to persue and I'll provide more details.

Roger