Hi Dan, I hope I can help.
I buy “slabs” of burl, including quite a bit of maple. The slabs come in averaging 2 to 2 ½” thick by various diameters with some up to three feet across. I cut them into 2.5” X 2” X 5.5” blocks on my table saw. By doing it this way, I can choose how to get the best figure out of them. You have to expect quite a bit of waste since you are cutting rectangles out of a circle so to speak. Also, you need to be oversized because as someone already said, you will get some warping, checking and cracks by drying the wood faster than normal. Once it comes back from being stabilized you can then recut it to size and remove the problem areas.
BTW - the reason I started buying my burl this way was because I noticed that many of the suppliers were either offering substandard quality or charging quite a bit for "the good stuff". However, and here is the caveat - there are a few great companies out there that still offer superior quality burl at reasonable prices (Burl Source and Ankrom are two that come to mind). However, on domestic burls, after doing the math, I was able to save approximately 40% by drying the wood myself and sending it out to be stabilized. More important to me than the money was to be in control of the figure within the blocks. You will be amazed at all the options you have when you cut it yourself.
To dry them I built a simple, yet very effective “hot box”. You should be able to build one for less than $60 which is cheap considering that you may have several hundred dollars worth of quality burl there.
Here is a list of equipment you will need.
(1) Coleman type cooler – metal, plastic, but definitely not Styrofoam by itself. Check Craig’s List which is where I found one of the oldies but goodies in stainless steel for next to nothing.
(2) An old fashion work light – the type with the cage around the bulb and a hook on top.
(3) A thermometer used with a Turkey fryer – the type with the dial on top of a 12” probe. You can find these at Home Depot in the BBQ section.
(4) A small piece of chicken wire or rigid steel screen
(5) Several wattages of conventional light bulbs – more on that later.
First, remove the drain plug from the cooler and if necessary increase the hole to approximately 1” in diameter. Then on the opposite end, drill a dozen or so 3/8” holes along the top edge about 1.5” down from where the lid seals. Then on the same end, drill a 3/16” hole about midway down from the top along the front or back wall. This is for the thermometer probe to go into. Try to do it so the probe fits right along the inside wall so it doesn’t interfere with the wood blocks you’re going to stack inside. Install the thermometer.
Next, pull the cord of the work light through the drain hole from the inside to the outside leaving just the work light in the bottom of the cooler. Install a 40W bulb in the work light. Do not seal around the cord running through the hole. You want a bit of room there. Fashion a rough “box” from the screen to go around the work light – you want to keep the burl a minimum of 2" away from the cage on the light especially if a piece were to fall over.
Load the burl blocks into the cooler on end – do not lay them down as you want as much surface area exposed as possible. You may stack them one on top of the other to make a second layer just make sure that you can close and latch the lid. Good square ends will help a lot with the stacking. And of course, do not stack the blocks on top of the wire cage and/or work light. You need to be able to get to the light to change bulbs if necessary and you don’t want to risk them getting too hot for obvious reasons.
With my hot box I found that a 40W bulb will bring the inside temp up to about 120F which is optimum to dry the wood fairly slow. A 60W will bring it up to about 160F which is too hot for my liking. It will dry the wood too fast and possibly warp the plastic on the inside of the cooler. The reason I say to try different bulbs is that not all coolers have the same insulation capabilities and you may need a higher wattage bulb to get to the 120F point.
And don’t worry; 120F is well below the ignition point of the wood and the cooler. FYI – decayed wood ignites at 150C or 302F; Polystyrene (which is what most modern coolers “innards” are built from) melts at 120-150C or 248-302F and it ignites at 488-496C or 900F+.
The reason you don’t seal around the drain hole/cord is that you want cool air to be pulled in from the bottom to create a convection effect as it exits the 3/8” holes on the opposite side towards the top. Remember - hot air rises. Once the blocks have come up to temp, you will be able to feel warm air being forced out the small holes on the end.
Now, buy yourself a moisture meter. They can be found on the net for under $40 for a decent one. I taped a piece of paper to the top of my box and recorded the date the wood was first put in, the moisture content and the temperature. Let it “cook” 24/7 and check the moisture content and record it as frequently as you like but at least once a week. For good measure you should check various blocks from multiple locations inside the box. You should also restack or rotate the blocks at least once a week as well so that you get uniform drying throughout the load.
Once your wood reads 8% or below for two weeks in a row they should be good and dry and ready to send off for stabilizing. There are several good companies out there that offer stabilizing at a fair price. Actually, they are all very competitive.
I hope this helps you and others. Email me at
info@jarrettknives.com if you have any questions.
__________________
Best regards,
Wayne
Full Time Maker
Member of the Professional Knifemakers Association
www.jarrettknives.com
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