Expert: Jamie Yocono - 1/23/2009

Question
Hi Jamie,  We have cut down many trees to build our home.  We used the oak to make our floors. We went through all the processed to dry the floor and it came out great, but was very costly.

We have a couple of cherry logs that we lost in a storm a year ago.  They have been just sitting outside while we decide what to do with them.  We are now doing a fireplace and would like to cut one for a mantel.  We would like to go about 4-6in. thick. We are having our stone done in about 3 weeks, can we just cut the log and use it or do we have to do some drying of it?? We probably wouldn't have to worry about warping.

thank you,
Bobbie

Answer
Bobbie,

I don't do a lot of work with air dried lumber, but I can give you a few tips. If that log is just sitting out in the elements, there's a good chance that the outside bark feels relatively dry, but the inside wood has a much higher moisture content. When you mill it into a rough mantle shape, you will be exposing the moist wood to air. That will cause it to dry out and eventually crack. That's why the ends of your log probably have some cracking and checking on them.

There are a couple of things you can do to minimize the cracking and checking. But first, you'll need to cut that log down. You don't want to cut it to the exact size and shape of your mantle, because you'll probably lose some of the wood on the ends to cracks. So I would cut the mantle oversize if you can, say 6 or 8" longer than you need, and maybe an inch or two thicker. To slow down the moisture loss, many woodworkers coat the wood with a cheap polyurethane, that seals the pores and stops moisture loss. Back when I was taking sculpture classes and carving fresh logs, I coated my log everytime I cut into a new section, exposing fresh wood. The coats of poly don't have to be pretty, just slap it on to seal it up. You're going to plane or cut all those sealed edges off anyway, but you need to slow down the loss of moisture, so the log doesn't go berserk.

There is another product called Polyethylene glycol-1000 (PEG), it is a substance that keeps wet wood from cracking and checking. Here's a link to read about it:

http://209.85.173.132/search?q=cache:xVk5cM1lN_sJ:www.fpl.fs.fed.us/documnts/pdf...

Back when I used to turn rolling pins on the lathe, I would strip all the bark and sap wood off a log, and then soak it in PEG for a week or two. After I pulled it out, I could turn a rolling pin and then wood was perfect - never a split or crack to be found. Peg looks like wax, you dissolve it in water, and then soak the wood in it. It never goes bad, so if you have a bucket of it, you can use it over and over, adding more water to it.

If I were making that mantle, I would rough cut the log like I said, keep polyurethane on it, and let it acclimate in an unheated area, like a garage for a while. Maybe a month. Then bring it into a heated area for a month, to acclimate more. Then machine it down to it's final size and recoat it with poly again. It should be dimensionally stable by then.

I know this schedule will probably take longer than you had hoped for, but simply cutting and milling that log up into your mantle is a recipe for splitting and warping. Try to do this very slow, to acclimate the log slowly every step you take, and you will probably have much more success than rushing it.

Good luck, write back if you need more advice or have a question about anything I've written.

Jamie Yocono
Wood It Is! Custom Cabinetry
Las Vegas, NV
www.wooditis.com