The Forestry Forum

General Forestry => Drying and Processing => Topic started by: Jrhkc0812 on January 01, 2019, 08:42:51 PM

Title: Drying black walnut slab
Post by: Jrhkc0812 on January 01, 2019, 08:42:51 PM

I currently have a black walnut slab air drying in the loft of my I heated garage in upstate NY. The slab is 2” thick, 20” wide and 12 feet long. It has been in the garage for two and half months and is at 35% moisture according to pinless meter.  I intend to use the slab as a bar top in the basement of my house. I am wondering if it is okay to move the slab to the heated basement of the house to finish drying or if it would be too aggressive and cause problems. Or is it okay to install the slab as bar top now as long as I don’t finish and fasten it down? 
Title: Re: Drying black walnut slab
Post by: WLC on January 01, 2019, 09:11:02 PM
Firstly, welcome!!

Just from what I've gleaned here I would wait until it got down to 20% or lower before moving it inside.  I'm sure you will get someone with actual experience that will answer your question in a little while.
Title: Re: Drying black walnut slab
Post by: YellowHammer on January 01, 2019, 10:10:44 PM
I would leave the slab where it is, assuming it seems to be drying fine, until it reached the Fiber Saturation Point at about 25%, give or take.  Typically, I will air dry slabs until under 20% before I will even put them in a kiln.  
I personally use the rule of thumb that “When the board reaches 20% moisture content, then 80% of the potential drying problems are in the past.”
Title: Re: Drying black walnut slab
Post by: Ianab on January 02, 2019, 03:11:53 AM
Moisture meters aren't accurate over about 30%, so it's likely 35% is the maximum your meter will read. It might actually be wetter. Also wood doesn't really start to shrink and move until it gets to the ~25% FSP that Yellowhammer mentioned.  Drying problems tend to occur if you dry too fast, so the outside of the wood gets too much below 25%, and the core is still green. Now the skin starts to shrink, and the core doesn't. So you have to dry slow enough for the moisture to move through the wood and escape. 

So I agree, wait until at least 20%, and I'd prefer more like 15% for a bit more safety. Even then, the board is till likely to move as it completes it's drying. But it should at least stay intact, even if it's not completely flat. 

In a perfect world you would want to get it down to 8-12%, depending on where you live. Then machine it flat, and it should stay that way.