Alternating growth rings in panels
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The debate between alternating growth rings and matching grain. September 25, 2002
Q.
What do you do when gluing up panels? Do you alternate the growth rings or just lay out a panel with the best side facing in one direction? This is in regard to custom cabinetmaking in a small shop, whether for solid dining table tops or five piece doors.
Forum Responses
I try to alternate the growth rings whenever possible. I feel the color and grain match is more important so it is not always possible to alternate. I tend not to use wide boards to glue up panels, which helps.
There are advocates of both. I like to match grain, etc. and will sometimes not alternate for this reason, but mostly I do. I think it is safer if there is going to be a delay between making your panels and incorporating them into a piece. During this elapsed time, non-alternated boards can cup significantly.
If you leave final thicknessing late and have cut your pieces thick enough, it does not matter too much, but I hate to waste wood and never leave more than an eighth for thicknessing and I often don't incorporate the panels for a week or two, hence my preference for alternation.
I'm going to go out on a limb here. I don't think alternating the board faces (heart to bark) accomplishes much, if anything. I do think that flipping pieces sawed from the same board end for end can help.
In any case, I believe what you want to do (if you do anything other than keep the most attractive faces exposed) is reduce warpage. Flipping end for end may cancel warp by creating two opposing tendencies.
That said, if I were you, I'd select the best faces to show, glue up my panel, sand it flat in a wide-belt if possible and finish with a good protective coating.
We always try to alternate and keep the strips under 3" wide. Trying to restrain a panel that wants to warp will only increase the likelihood of a cracked panel.
I toured a major high-end solid wood furniture plant. They used to say make all the boards smile at you.
Put the heart up, don't alternate. Imagine - if the growth rings straighten out, a board becomes convex on the heart side. If all the boards do this together, then the top rises in the centre and/or drops at the edges. Isn't the best place to hold a top to the base in the center of the width, so seasonal movement is working against fastenings that are close together? And the edge of the table is forced down against the apron by drying? Also, alternating guarantees a washboard effect you can't control, while heart up usually shows the best face of a board and is predictable and therefore controllable.
I tend to agree - 99 percent of boards will cup away from the heart. So in gluing up a panel, then making furniture, I can accommodate for that, but how do I accommodate for a washboard effect?
If the moisture is controlled, then the washboarding will be, too. Dry the wood correctly, store it correctly, keep the RH in manufacturing controlled, and use a good VAPOR resistant finish. (Broken record?)
Gene Wengert, forum technical advisor
