I hadn't thought of that (yeow!). But then, like the IKEA original I patterned my bookcase after, I didn't really expect it to last beyond 10 yearsOriginally Posted by Mel Fulks
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I hadn't thought of that (yeow!). But then, like the IKEA original I patterned my bookcase after, I didn't really expect it to last beyond 10 years
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Amen to that. Do not use contact cement on raw wood veneer. Contact cement is intended for millwork applications. And as Mel said, it often starts to come apart too soon.
Almost any furniture glue can be used with veneer. I've used PVA, epoxy, cold press, and urea formaldehyde. They all work well in the proper setting. Epoxy is good because it doesn't contain water, and water makes veneer expand. When doing a radial match, water based glues can be a real problem.
Mike
Go into the world and do well. But more importantly, go into the world and do good.
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I agree that the vacuum system is ultimately the best solution to use for this kind of thing because of its ability to provide even pressure over the entire workpiece. For flat pieces, using platens to surround the workpiece essentially creates a "clamp" over the whole thing. I use MDF for that.
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The most expensive tool is the one you buy "cheaply" and often...
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Vacuum bagging is a no-brainer, If you have a vacuum pump you already have the most expensive part. I've made bags from heavy plastic drop cloth taped closed with clear packing tape. A bit leaky but worked well. I bought one of Joe Woodworkers vacuum bags for my most recent veneer project and it is a very nice bag, worth the money.
Also be careful how thick you go on the veneer. I've been told by people with much more experience with veneer than me that anything over 1/16" starts to behave more like solid wood than veneer. This is particularly a problem if you are joining multiple pieces of veneer since the joints can open up or the glue line can telegraph proud of the surface as the thicker veneer moves with moisture changes.
I also prefer the urea formaldehyde glues mentioned already. I've used the Weldwood and the Cat-5 with equal success. They are the same product from what I can tell.
Good luck!
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You have to be careful using solid cauls over shop sawn veneer, actually any veneer, if it has thickness variations. If the thickness is not dead constant the solid cauls will bridge over the low spots and those low spots will not get pressed and end up poorly or completely unbonded. Breather mesh between the cauls and veneer will prevent this. But at that point you only need a bottom caul with breather mesh on both sides of the veneered substrate and the bag directly on top. That gives you a flat panel with the most uniform pressure possible on every square mm.
John
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With epoxy glue I simply use weights.
"Anything seems possible when you don't know what you're doing."
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I use carpet padding under a caul - the "rubber" type of carpet padding that looks like it was made from small pieces of different color foam. Of course, I put a layer of plastic under the padding so if any glue comes through, it won't glue the padding to the veneer. I find that gives me good even pressure.
Paul Schurch uses a heavy cloth, like sailcloth, and that works also.
Mike
I never tried it, but I have some fairly thick cork in roll, about 3 feet wide. I could glue that to the underside of a caul and that would probably work, also.
Go into the world and do well. But more importantly, go into the world and do good.
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I'm really surprised no one has brought up Unibond one, we've been using it since its inception, we've had excellent results both with veneering (thick and thin veneers) as well as bent and straight laminations, the unibond has a very hard glueline and is thick enough to prevent bleed through (to a point), with a one hour press time,
We always go for the bag or press, if your only a few parts away from using a pump I would recommend it, big time saver along with solid results.
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I took a similar approach, Mike; I used a 1/8" thick closed cell foam silicone mat that has about 25% compression at 10 psi. That worked great, but then I realized that the better approach is to use breather mesh. The reason the breather mesh is superior is because it lets the vacuum come between the caul and veneer so you get absolutely equal pressure on every square mm. Your carpet padding may in fact do the same thing if it's open cell, as would sailcloth. I'm actually using heavy duty plastic window screen material which is really cheap and lasts a very long time. In any case, two cauls is unnecessary. I'm not sure even one caul is needed for flat work if your bench is flat. It does no harm, but I'm not sure it actually does any good.
John
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I'm going to look for that heavy duty plastic screen material, John. That sounds like a good idea. Where did you find it?
I've been using screen for breather mesh but the regular screen material. It works as breather mesh but is too thin for anything else.
Mike
Go into the world and do well. But more importantly, go into the world and do good.
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I got my mesh from Joe Woodworker
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The most expensive tool is the one you buy "cheaply" and often...
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I get it at Home Depot, Mike. It's available in several different widths and lengths, too. Look for the stuff labelled Pet Screen. You'll see how much thicker it is.
John
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I got some from Joe, also. But it's fairly expensive from him. What John is saying is that the heavy duty plastic screen is really inexpensive.
Mike
Go into the world and do well. But more importantly, go into the world and do good.
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Interesting idea on the screening. Trying to think of a situation where that would be a good solution for my process. Does someone have a diagram?
For me, if doing something flat I use a kerfed platen inside the bag to provide vacuum equalization underneath the object being glued. I suspect that is the function for which you are using the screening? If I add breather fabric between platen and object it serves to absorb glue squeeze out. It doesn't seem like a good practice since it could reduce flatness.
Trying to think of pros and cons of having the equalization inside or outside the platen. Joe Woodworked shows it outside, but I typically put it inside. I guess I worried the bag would close off the kerfs.
If I'm doing a wet layup – bagging on a "skin" of resin impregnated cloth – and want that to conform to the shape without inducing flatness, I would wrap entirely first with the release (peel ply typically) film, then with flexible polyester breather. The release film provides a secondary adhesive surface and minimizes excess resin. That's my standard approach for making say, a foil. I'm pretty liberal with the breather because it is quite inexpensive. Sometimes in a jam I use clothes for breather.
Last edited by Bill Adamsen; 12-15-2017 at 3:22 PM.
"the mechanic that would perfect his work must first sharpen his tools.” Confucius
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The problem with his product is it's really coarse and stiff, and if you get a wrinkle in it it's impossible to get rid of. The window screen mesh is much more compliant, available locally, and cheaper.
John
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