Seasoning a Large Hardwood Slab

A premium slab is a treasure, but drying it properly requires patience and nothing will stop it from moving as it dries. April 30, 2006

I have a slab of European copper beech 9' long x 38" wide x 4" thick. It's been air drying here in CT for approximately 15 months. MC is 20% with a mini Ligna, temp about 45F. (I did reading after full day inside, temp. at 52F.) I have planed and sanded surface to show a prospective client who'll be looking at it on Monday. It is very figured, with some spalting at edges, some small cracks, etc. She may want it for a dining room table.

Do I need to dry it below 10% for it to be usable? I wouldn't mind it moving a little - I don't want it smooth like a conference table. At 4" thick and secured with angle iron across width, do you think it will cup, warp, etc.? Even if it's finished all sides? What would you recommend for a finish? I did an air dried table with Danish oil, but it was for my conference table and doesn't get a lot of use or abuse. What would you recommend to keep slab from cupping if it's only resting on, say, stone legs (no apron)?

Forum Responses
(Sawing and Drying Forum)
From contributor R:
Using that steel will actually cause it to bow and split. The wood will shrink when put in the house, the steel will only add a little strength to one side. The top will shrink, the bottom will less, the top will become concave. At 15 months it just has a good start at drying. For air drying, that slab should sit at least 4 years, maybe more. The meter you are using is not measuring the moisture in the center of 4 inches. It probably only measures 1" deep. It will move as it wants to - nothing will keep it flat, nothing! I would use a polyurethane for the finish, about 3 years from now.

From contributor J:
Try to find a local vacuum kiln. Should be able to dry it in a matter of days.

From contributor I:
If it's still over 20% MC now, then yes, it's going to move a bit more as it dries. Finishing or bolting it down isn't going to change that. Coating the thing all over with poly will just delay the inevitable. I have to agree that for a piece of hardwood like that, it's better to stash it back in the shed for a couple more years, then plane any warp out of it and build the table. Or get high tech and vacuum dry it. 20% on the outside is just not dry enough. Should be awesome when you do get it finished, though.

From the original questioner:
Thanks for the prompt replies. I did wash it down with some mineral spirits to see the figure and yes, it'll be awesome. It seems the answer is a vacuum kiln.