Wood Drying Techniques

Mike Martinez

Well-Known Member
After seeing quite a few posts asking for advice on processing burls and raw wood, I’ve decided to weigh in with my experience.
At the height of my custom brush and pen turning I was going through about a hundred pounds of wood per month, which isn't much in comparison to bowl turners or even some of the more prolific knife makers but it did impart some lessons upon me.
The first thing one must do when considering processing raw wood into scales and blocks is realize that there is much waste involved as there are no guarantees to how much of your raw material will survive. We have to take special care to avoid careless waste which can be prevented with minimum effort.

1. Purchase a moisture meter to determine MC% (moisture content). Not the best, but this one will fill our needs: http://www.woodcraft.com/PRODUCT/208...FSdp7AodtD0A8g

2. Understand the species with which you are working. Madrone burl will react differently than Mesquite, or Amboyna. From what I have noticed, the higher the initial moisture content, the greater the chance for checks, cracks, splits and honeycombing. Species that are prone to quick moisture changes benefit from boiling (will be discussed shortly).

3. Be patient. Though there are techniques that can be employed to lessen drying time, few of them, if any, will give you the same positive results that proper seasoning will.

There are many techniques to hasten the drying process and some are necessary for processing certain species that are prone to movement. Below is a quick list of the more effective:

1. Boiling some species, such as the aforementioned Madrone burl, can shorten its drying time as well as increase its yield by helping prevent honeycombing.
I. Cut blocks of wood down to a manageable size ( If I’m aiming for 1 ½ x 1 ½ x 5 blocks, I prefer to cut a larger block at about 2 x 6 x 6 which will later be cut down to working size)
II. Place blocks inside a stock pot with cold water and bring to a boil
III. Allow blocks to boil for at least 2 hours
IV. If the wood is prone to movement, after boiling for two hours, allow to cool in pot over night. If the wood is not prone to movement, you can remove the block after two hours.
V. Once the blocks are removed from the water, wrap completely in newspaper or place inside paper grocery bag and store in a cool dry place (use sticker if staking them).

Boiling should cut your dry time down to about 2 months depending on the size of the block. Boiling can be done with any species of wood but it isn’t necessary unless dealing with the likes of Manzanita Burl or Madrone Burl.

2. Kitty litter

I. Place kitty litter in bag or box
II. Place blocks of wood into kitty litter and cover
III. Check MC% every week or so until you’re down to sub 10%
IV. Remove blocks from kitty litter once the proper MC% has been reached.

The kitty litter method will work quickly, about 4 weeks for large blocks 1 ¾ x 1 ¾ x 6 so use it only on woods that are naturally stable such as Mesquite, Osage Orange, Persimmons, etc. Kitty
litter can be reused after dehydrating in an oven.

3. Hot Box

I. Find or make a box (rectangular or square)
II. Place 60-100w light bulb(s) (one for every 12” of length)
III. Cut an opening at one end of the box (you will be inserting a fan so cut it accordingly)
IV. Place fan at the opening that you created
V. Place a thermometer to gauge temperature

The hot box isn't as easy as the others but if you have even the slightest knowledge and ability to work with electricity, you will be able to approximate a kiln.

If you choose to stick to traditional seasoning methods. Remember to seal the end grain of your blocks. For this you can use latex paint, paraffin or Anchorseal (optimal). You can also wrap them in newspaper or bag them to slow down their loss of moisture. Hopefully this keeps you guys from having to wait months or years for a whole burl to dry enough to process. Most woods can be processed green (always cut oversized) if handled correctly afterwards. Remember that depending on species, your safe rate while drying should be from 1 to 4.5%. Denser/ oilier woods will dry at a slower rate whereas everything else will dry a bit faster.

With any luck this isn't too garbled to decipher. I hope it helps.

Regards,
Mike
 
Great tips Mike,If I may also add ,the slower the wood dries the better off when stabilizing you are .I have wood sent to me from all over the world and as a professional woodworker and stabilizer , it's easy for me to spot the wood somebody has over heated , trying to ( speed ) up the process. when doing so you collapse the cells making it impossible to saturate properly. another way to speed up the process , one that I use , is to soak tour blocks in denatured alcohol for a couple weeks ,and let them slow dry until all the smell if gone.
 
Some excellent information. Some people work with wood for many years before learning all that.

A common misconception I hear often is "I know it's dry because it was kiln dried"

Wood is hydroscopic, it's like a sponge. It takes on and releases water according to the relative humidity of the air.

It doesn't matter if it was kiln dried or cut 50 years ago. The moisture content still fluctuates. Unless its stabilized.

How much it moves depends in the species of wood and the grain direction.
 
Great information Mike, appreciate you sharing it.
I have used a "hot box" for years now. I converted an old military foot locker. 2 - 100watt bulbs on a Christmas light timer. It cycles 6 hours on 6 hours off. I keep ALL my natural handle material in there. Stag as well as wood. I have some holes cut into the top on the sides to allow air movement. My question would be how important is it to have a fan? Is natural convection not enough? If a fan is needed what size? How much air is needed to be moved?

Thanks and God Bless
Mike
 
Mike, I've used large computer fans on each end. I find that you get better drying with improved air movement but you have to be careful to not overdo it. And to answer your question on convection, yes its enough so long as you don't have them stacked atop of one another (using stickers). If they are stacked, you will get slower natural movement in between the boards.
 
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