by Professor Gene Wengert
Q.
Is there an easy way to flatten flitch stock veneer before hot pressing to minimize cracking? If so please explain.
A.
I believe that what you are referring to is called buckle. To remove the buckle without cracking the veneer is difficult, as the reason the buckle is often due to a veneer peeling problem, can be caused because the wood shrank unevenly during drying, can be a result of uneven final MC. I would guess that most often, uneven MC is the culprit. In any case, the cure for buckle is in the drying process, not at the point you are ready to glue it. (So, putting pressure on your supplier is the ultimate cure--buckle is not inevitable.)
You can make veneer more flexible by increasing its MC. (Which means that over-dried pieces have a high likelihood of cracking, which are also the pieces that will have the most buckle.) If you increase the MC slightly (but not above acceptable limits for the product that you are making) and then press the veneer flat, using a little heat even, you can flatten it a little--but this is a lot of effort to correct a manufacturing flaw.
Professor Gene Wengert is Extension Specialist in Wood Processing at the Department of Forestry, University of Wisconsin-Madison.
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