Drying Heavy Oak Timbers

      Expect a lot of checks and cracks. October 2, 2005

A customer asked if I would dry 9" oak for mantle pieces in my kilns. I told them that it would take forever. I heard other people say that it would work okay to just apply the finish and sealer (to slow it down) and let it dry on its own. They asked if an oil would be a good enough sealer to slow it down? Any thoughts?

Forum Responses
(Sawing and Drying Forum)
Your question is a little vague. I guess that since you said 9" thick, it is safe to assume that it will be thicker, and that you must want a natural edge. Otherwise, why not build a box out of thinner stock?

I am using green wood for more projects lately, and find it rewarding. As was suggested, applying some finish will retard the surface evaporation rate, which will allow moisture to arrive at the surface at a rate close to the evaporation rate into the atmosphere, and reduce checking. If that sounds easy, keep in mind that sapwood is more absorbent and desorbent than heartwood, and might need more finish than heart, and that the ratios between radial and tangential always make a difference in the final equation, thus I like to stay as far away from the heart or juvenile wood as possible, to keep those small curving annual rings out of the equation and keep the ratios down to an X - Y axis.

Having said all that, you should tell your customer to expect some checking, but that it may close up some with time. If the checking happens while it is in your care, rather than hiding it, you can round out the edges a little with sandpaper, which gives a bit of rustic charm.

I prefer some of the modified oil finishes which contain sealer, yet soak into the surface before setting, over straight tung and linseed or the topcoat finishes. Be sure to apply finish liberally to the end grain, and maybe even work in several coats of wax to slow the moisture loss there.

From the original questioner:
Yes, they do want the natural edge. The wood is for fireplace mantles. Your response is a big help. Also, they are going to do some carving on the wood first.

What kind of oak? 9" thick white oak will take years and years to dry, and guess what happens when they build a fire and you have a wet stick of white oak above that? Tell them to expect some cracks as big as 1/2" wide to prepare them for the worst. Keep it as close to quartersawn as possible, dead straight grain if possible. Ask them if they have ever seen a barn beam without cracks. Tell them to expect some real dramatic noise from the beam as it dries out in the house. Might sound like a 22 caliber sometime in the middle of the night. We cut some western red cedar for knee braces one time in our shop, dead of winter. It sounded like Rice Crispies (snap, crackle, pop) when the fresh wood was opened up and the humidity in the shop was under 30%. Don't guarantee anything on a beam that thick.

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