The various discussions on ways of drying wood prompted me to post this message.
The following article was published in the March 1998 issue of More Woodturning. I authored the article with technical help from Gilbert Brown of Omak, Washington. Gilbert had done considerable experimenting with his process and was trying to market the system with little success. I wrote the article and submitted it to Fine Woodworking. They kept it for a year and then returned it saying that their experts said it would not work. I leave it to the reader to determine whether this might be useful.
I first met Gilbert Brown at the 1993 ?Art in the Park? craft fair at Omak, Washington. Several of the bowls on my table were turned from wet wood and had warped appropriately. Gilbert said, he was working on a project to dry fresh cut wood fast! With his planned system, he said, we wouldn?t have to turn green wood and guess at what its final shape might be. Being a writer, I told him it might make a good article. Since then, we?ve crossed trails several times. Each time we met, he hadn?t perfected his dryer yet. He was still working on it.
Then ?out of the blue? he called me. His project had finally been worked out. His system can dry a kiln full of wet (newly cut) fruit wood to 6 percent moisture content in three to seven days depending upon the thickness of the timber, about the best I?ve heard of is almost a month. This new system uses a low temperature (100 to 150 degrees) and a vacuum pump. Gilbert says, he isn?t going to mass produce these units but will make one up for someone on special order. If interested, you can contact him at: Gilbert Brown, Route 3, Box 336-B, Omak, WA 98841. You can call him at:
509-826-4058. (Note: Gilbert wasn't in extremely good health at the time I wrote this article and he may no longer be able to produce a unit on order.)The unit that Gilbert has devised uses a two-foot diameter steel tank that is 10 feet long as his vacuum chamber. One end of the tank has a door that can be opened for loading and unloading the chamber. The door is equipped with a small Plexiglass window so that the wood can be viewed during the drying operation. A light bulb is also installed in the tank to assist in this.
The vacuum tank is mounted inside a wooden box with an air chamber between the tank and the sides of the box. The walls of the box are one to two feet thick with sawdust used as a filler and for insulation. A tube type thermometer is used to measure temperature within the vacuum chamber. Finally, a vacuum is pulled; a reading of 15 on the gauge is adequate.
When loaded with wet wood that has been brought up to temperature, beads of water will appear on the ends of the boards about six minutes after the vacuum is established. Apparently, the moisture is removed from the wood along the channels that the moisture moved in when the tree was alive. You don?t get to view what?s going on for very long before the window is fully fogged with moisture.
Gilbert has been making lumber from fruit wood stumps. He says, a cherry wood stump that is three feet long and about 16 inches in diameter weighs about
300 pounds. Such a stump will produce about three gallons of water in three days. This water collects in the bottom of the tank. He has installed a drain valve in the bottom of the vacuum tank so that the water can be removed and saved in another smaller tank without losing the vacuum.This dryer was developed to quickly dry fruit wood from the orchards around Omak, Washington to produce cabinet grade lumber at the lowest possible cost. Gilbert uses the stumps that regular mills leave behind. Here, much of the figure in the tree exists so that really fine wood can be obtained from a part of the tree that would otherwise be burned. Of course, this process doesn?t yield long pieces of timber, but most cabinets don?t need very long pieces. Gilbert also makes up fancy flooring from this wood by laminating the pieces to form larger boards with an appropriate pattern.
Fruit woods will twist a good deal during this fast drying process, unless they are clamped down while drying. Other woods seem to be alright, he says. Gilbert described a typical load of fruit wood to be boards that are about one inch thick, either trimmed up or with the bark left on. The boards are stacked on a 1/4 inch metal plate. They are then clamped down to the plate to hold them in position while they dry. Once dry, Gilbert says, the boards are OK. Wax sealer on the ends of the boards will help to keep them from cracking.
Currently, I have quite a bit of wood on the shelf that was cut six months to two years ago that still isn?t ready to turn. I?m waiting for it to air dry at about one inch per year. I can see how a small kiln of this type that would hold a few green wood bowl blanks or several small pieces for other turning projects would be very useful. I turn small pieces such as wine bottle stoppers and spinner tops. These must be dry before you turn them. A small kiln with a vacuum tank about the size of a five gallon bucket, which wouldn?t take up too much space in my shop, would work well for me. I could dry more wood with such a small unit than I have time to turn.
Editor?s Note: This article was written for Fine Woodworking in cooperation with Gilbert. After almost a year, Fine Woodworking returned the article, saying that the ?experts? they had contacted said the system wouldn?t work. I don?t make any claims about Gilberts system, but I believe he is honest and that he has worked out a system that will dry wood quickly. I have held off publishing this in More Woodturning in hopes that I could find a publication with larger circulation to spread the word about this system. Anyone wishing to investigate this further should contact Gilbert Brown directly at the address given above. The way he talked, he would be willing to make up systems of virtually any size.
Fred Holder