Flattening Burl Veneer

Veneer pros describe the formulas and methods they use to make burl veneer flat and pliable before pressing. June 28, 2013

Question
I am restoring a desk and the drawer pulls were all made of wood, all but about two are gone and they are badly damaged. They have veneer on them and they are only about 1.25 wide by 7 long. I have a vacuum press and have done veneer work but not with burls or crotch. I cut some pieces off the burl and sprayed them with softener, and then I placed them in tissue paper and then clamped them between two boards. I waited 12 hours, replaced the paper, and repeated. I really don't know much about working with burls or crotch. How can I tell when I get them dry enough? Also do I need to cross-band this? I would think not considering it is so small of a piece.

Forum Responses
(Veneer Forum)
From contributor D:
We may be overkilling it, but when we flatten burl veneer we change the paper twice a day for five days. Our results have been good. The cross-banding shouldn't be necessary unless the veneer is so fragile that you need to stabilize it prior to pressing to the substrate.


From contributor H:
Depending on the recipe for the softener, the damp flattened veneer can still be reliably adhered to the substrate. When the veneer is flattened then dried, the unruly characteristics of the veneer will return. I apply the softener to both side of the veneer, let soak in a few minutes, and then press carefully and slowly between two sheets of coated paper. At this point I am looking for flat, not dry, with the least amount of damage to the veneer.

Only when the veneer is flat can accurate matching happen. Once the veneer is taped in to the larger pattern, it will dry on its own. This may or may not cause further problems depending on the amount of curl in the dry veneer. Sometimes this larger sheet will need flattening prior to pressing. Veneer with the softening solution still damp can be adhered to the substrate in your normal way. Why wait five days or even 12 hours? Moisture content in veneer is not nearly the problem it is in solid lumber.

How fragile the burl veneer is should be a factor in whether to cross band or not. I would press the cross band and hand apply the cross banded veneer to the pulls using hide glue and a hammer.


From contributor D:

The reason we came up with five days is that even after that length of time the veneer still had an almost plastic feel to it and was still flat and easy to work with. We did some testing and found that pressing the veneer earlier caused some shrinkage along the joint lines that would transfer through the finish. I will certainly acknowledge that that may be caused by a flaw in the veneering process we use after the flattening stage. We just kept trying different solutions until we came up with something that worked.

From the original questioner:
I was going to use high glue and Spanish cedar for cross banding.

From contributor H:
Where I live glycerin comes in 4oz. bottles, so these proportions are keyed to that. It makes about a quart. Unfortunately, the viscosity is too thick for a spray bottle. I use a brush to apply the solution to both sides of the veneer. If the veneer is especially curly or dry, allow the solution of soak in before pressing. Protect the veneer from the cauls by (always) pressing between two sheets of coated paper.

Ingredients:
8 oz. water
5.5 oz. of white glue
4 oz. of glycerin
3 oz. of denatured alcohol

Stir before using.


From contributor D:
I’m new to veneer. What are "coated papers"?

From contributor I:
Welcome to veneering. My first advice is to take every step of your veneering process seriously. You don't want all of the creative work you and the tree have done to be lost to sloppy technique.

I use white butcher paper that is coated on one side with some film that does not stick and does not transfer to the veneer surface. I buy it in rolls from a local paper wholesaler equal to the width of my typical bottom caul. For me that is 30". The width is not important; you may have a 36" or whatever. I don't like seams in the paper, so I might have sized my caul to accommodate standard paper width. It is usually a one time use, any wrinkles in the paper will telegraph into the veneer. That is why I flatten one sheet only at a time, no stacking.

Early on I had been veneering directly on white melamine cauls until I nearly lost a chestnut burl top when a quarter of it, in random places, stuck to the melamine. Although I still use melamine cauls, I have never veneered without protection since.

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