Drying discs from a walnut log
Ideas for drying and protecting circular slices taken from a walnut log. November 15, 2000
Yesterday we cut down a good sized black walnut tree in our yard. We were going to use it for firewood, but I fell in love with the beautiful pattern of the trunk and would like to "slice" it into pieces to be used for a floor under the arbor of trees we are replacing it with. Should I dry it before slicing it? Then should it be sealed? It would have to be air dried as I do not have access to a kiln.
There is some information on using salt paste to season disks to prevent v checking in USDA handbook no. 528 "Drying Eastern Hardwood Lumber." They recommend mixing 3 lbs of salt with 1 gallon of water, then making a paste from that using cornstarch and several egg whites for a binder. Put a thick layer on the disks with the bark on and then air dry or kiln dry using a moderate schedule. I have never tried it but have kept it in the back of my head for future reference.
Cut the slabs thick and expect it to crack. I have no clue how decay resistant walnut is in ground contact. Here are some URLs to related articles:
Wow, that would be one very nice looking floor. I'll bet you find some other uses for the wood after you see what the grain patterns look like in the boards. Cut the log into boards as soon as possible and get them into stickered piles to start the drying process. Walnut is pretty easy to air dry. Air drying is all you need for the lumber since the floor is outside. Call Woodmizer for help finding a sawyer in your area to mill the logs.
I have read that you can take a round slice from a tree trunk, put it in the microwave, heat it until it steams and let it cool and then repeat this process a few times and it should dry without splitting. This kind of makes sense as the microwave probably heats the inside and dries the wood from the inside rather than the outside, which causes a round cut to shrink around the outside diameter and open up from the shrinkage.
Microwaving might work for some of the pieces, but rounds don't split due to drying from the outside in. They split because most woods have different amounts of shrinkage in the tangential vs. the radial direction. It is the difference in shrinkage that produces the cracks.
I work at Pleasant Hill, an 18th Century Shaker village museum in the Kentucky Bluegrass, and I have some advice to pass on from our coopers. Recently, the village had to remove a big sycamore and a big maple (died due to last year's severe drought). I asked the guys to save me some "slices" of both trees to be made into old-fashioned butcher's blocks (which of course I probably won't actually use due to scary stories about food poisoning!). Both coopers offered the same suggestions: 1) paint the cut ends of the slices, and expect to later sand or cut the paint off or 2) wrap the slices in plastic sheeting, but uncover periodically on cool overcast days so they don't mold. I'm gonna give the plastic a try--unless someone out there says no way.
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Comment from contributor C:
I tried the wrapping it in plastic trick about 10 years ago on a massive walnut disk that was about 6 inches thick (probably a bit thin) and about 3 feet in diameter. I tried to keep up with the mold, but it was a roiling, sleepless evil that foiled my every effort. It got so moldy that I was afraid to use it as firewood. Painting the ends sounds more attractive to me, and I'm intrigued by the salt and egg white potion.