Vacuum bagging for veneer on the cheap

I'd like to improve my veneering technique. Right now I apply glue (usually alephatic yellow glue) and either clamp or apply weights. This works OK with backed veneer. A lot of stuff is just "plain" wood however, and doesn't lay flat. I'm not able to develop enough force to flaten the veneer to the substrate. I'm looking at vacuum bagging as a remedy. The problem is that U have exactly $0 to dedicate towards this. Has anyone used common kitchen freezer-type bags for vacuum bagging veneer? I've got a couple of the hand-type vacuum pumps, and the volume is rather small so I think they would easily pump down the bag.
Anyone out there doing vacuum bagging and willing to give me some pointers? And yes, I've looked at several web sites and done google sesarches, but haven't found anything on freezer bags yet.
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Why not do the opposite? (As a matter of fact, I did just get off the ice. No, I didn't take any shots to the head. ;-)) If you're doing a small board, why not try filling up an innertube you've mounted in a frame, like:
_______ <- Top of Frame + *** + +** **+ <- innertube + *** + + --- + <- board and veneer &&&&&&&& <- benchtop
+'s are the frame sides.
As you fill up the innertube, it should put uniform pressure on the board, holding your veneer down evenly.
Puckdropper
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Wise is the man who attempts to answer his question before asking it.

To email me directly, send a message to puckdropper (at) fastmail.fm
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I appreciate your advice, and will think about it. Right now, though, I have freezer bags and no inner tubes.
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"Smaug Ichorfang" wrote...

As you've found, aliphatic resin glue works fine on backed veneers, as the veneer is already pressed to the substrate using an appropriate adhesive, and is fairly stable.
IME, however, yellow glue is a poor choice for gluing veneer to either a substrate or crossbanding - it's too "plasticy" and will creep, it will seep through the pores of the veneer and cause glue spots, and is hard to press really flat. Even with a really good vacuum veneering setup, IMO yellow glue would still be a poor choice of adhesive.
Better choices would be urea formaldehyde glue, cold press glue, or hide glue. Constantine's sells a two-part liquid urea resin glue called Press Bond that also works well.
Hammer veneering with hide glue is actually quite simple and with a little practice on some test pieces, pretty easy to get the hang of.
I realize changing adhesives requires spending $$, contrary to your intent, but IMO using yellow glue on good veneers is throwing $$ away.
-- Timothy Juvenal www.tjwoodworking.com
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Smaug Ichorfang wrote:

Flatten it.
1. Spritz lightly with water 2. Place absorbent paper on top (butcher paper works) 3. Ply on top 4. Weight.
Change the paper every day or so. If you have a stack of veneer, separate veneer+ paper with screen wire.
If you want it *really* flat, add a bit of glycerin to water spritz.
--

dadiOH
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On Sun, 09 Dec 2007 05:34:09 GMT, Smaug Ichorfang wrote:

Are you doing flat work (applying the veneer to a flat substrate)? Maybe using a platen will help flatten the veneer. Cut a piece of plywood a little larger than your workpiece, and cover it with plastic sheeting (the stuff sold for use as a tarp works well). Put that plywood plastic side down on top of your workpiece, and clamp or apply pressure with weights on top.
I have not tried using freezer bags for vacuum veneering.
I doubt that the bag seal will hold a vacuum well. It just wasn't engineered for that. You'll have to go back periodically and pump the bag down to overcome that problem. That's OK for fast drying glues, but not for the slower drying ones, such as plastic resin glue. (Yellow glue will creep with time, you should consider using a more appropriate glue for bonding veneers to a substrate.) Or maybe you could rig a closure similar to the kind used with "real" vacuum bags. But that will take away from the available working volume.
Aside from the seal itself, there are issues with those bags leaking elsewhere. I use freezer bags to defrost frozen stuff using warm water (the stuff I'm defrosting goes in the bag, and the bag goes into the warm water, open top out of the water). About half of the bags I've used leak. Brand does not seem to matter. Even a good portion of the "heavy duty" type have this defect. I suppose you could pressurize the bags beforehand to locate leaks, and attempt to seal them off. You could cut up another bag to make patches. I don't know what kind of glue you'd need.
Next problem is attaching a hose to the bag. I have no ideas there.
I also wonder if the glue you're using to bond the veneer to the substrate will stick to the freezer bag. You will have some squeeze-out if you use enough glue and apply sufficient pressure, and it would be very bad to have that stick to the inside of the bag.
You will also need to assure that you don't end up with trapped pockets of air in the bag. Depending upon where your vacuum connection is, this can be an issue. I bought a plastic mesh, sold for the purpose, that sits between the platens and bag. Maybe you can use a couple of layers of fiberglass screening for that. Again, though, I'd worry about squeeze-out sticking.
Me, I bit the bullet and I'm very glad I did. Having a real pump and real vacuum bags makes working with veneers almost pleasurable. But I'll admit, it was more costly than $0 to get that stuff.
--
Art Greenberg
artg at eclipse dot net
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