Say NO to cracks.

[cgarman]

I've been milling some large (32" x 8') red oak slabs (8/4") with my mill, and now that they're starting to dry, they're cracking more than I'd like. I treated the ends with Arborseal before opening the log, and I stacked them outside to dry slowly, before taking them in. It didn't work. I have a little checking on the ends (6") but the worst is the cracks in the middle of the slabs. Everything is stickered and weighted down, so there's no cupping, but I'm getting lots of tension cracks in the middle.

Have you guys figured out a way to avoid this? I'd like to figure it out before I get into the next 5 trees.

 

[Can8ianTimber]

First of all I love you tag line.
"Woodworker turned sawyer running a Stihl 076AV with a 56" bar, a driveway full of sawdust, and pissed off neighbors"
I have been there before only I was running an 066 6 hrs strait on a saturday. Quickly reallized that was not going to work

A couple things to add. Keep out of sunlight exposure. keep your stickers on either end as close to the end as possible, I try to do under 1" from the end. Last thing is some slabs just crack and there is no way around it, oak is very tough to dry.

 

[cgarman]

The stack IS exposed to sunlight, but I was afraid to cover it with a tarp. I had a stack inside, but it gathered a lot of mold between the boards. I figured a little sun (on the shady side of the house) would keep the mold at bay.

Do you toss a tarp over top to block the sun, or does that keep the air from circulating freely?

 

[TraditionalTool]

It's not the sun, IMO, it's the water. When wood gets wet, it will check/crack as it dries out. Letting the sun dry wet wood will cause it to check/crack as the sap/heart dries at a different rate. You need to keep the boards stickered properly also, to keep the mold at bay.

 

[gemniii]

I figured the wood will either crack as I air dry it outside, or crack later if I build something with it.
So I stack it, sticker it, then cut it up along the cracks with a circular saw.

I've got a coffee table built by an artist, Kennedy, in Underhill, VT back in the late 1950's or early '60's.
It's mainly a maple slab about 3" thick. It was flat. It didn't have cracks when my dad bought it. It developed a few about 20 years ago. It also "twisted" a little in the LATE 1970's. Different ambient humidity.

The wood knows where it wants to split. The wood will split if it wants to. The wood is older than I am and I respect it's judgement.

If I get a BSM I'll worry about cracks more. I can press it tight to "bend" it to my will, but it knows what it wants to do.

 

[BobL]

I'm not familiar with your timber but here its a lottery as to which ones survive and which ones don't. I keep the sunlight off and as much rain as I can but the ones I have stacked outside seem to crack as much as those inside. Cracks in the middle of full width of log boards are very likely as TT says the heartwood will shrink more than the rest.

 

[mikeb1079]

interesting that you're having this problem with red oak. i too have cut some red oak that i dried on the full shade side of our garage and it cracked/split pretty badly. now some splitting i know is inevitable but the oak split much worse than the cherry and maple that were right next to it. i've since read that oak is an exceptionally slow drying species so it makes sense that it's prone to crack. what i'm going to try next time is full shade and a loose fitting tarp over the open air side to see if i can slow the drying even more. don't know if it'll work but i'll let you guys know if i find out anything.
good luck.

 

[TraditionalTool]

Checking is really only caused by one thing, the process of the moisture content of the wood going down, and the sap/heart contesting each other during that process. If you let the rain have at your wood, you will get more checking. And the more it gets wet and dries the worse the problem.

Also consider that the proper way to cut hardwoods is to split the slabs to relieve the tension in the pith, that is where the majority of tension is. This narrows the boards substantially to less than 1/2 width if you want to remove the pith entirely.

The way you slice up a tree is really an art form, and it makes a huge difference in how the wood checks after the fact. The whole idea behind quarter sawn wood is to get the more stable section of the tree. True quarter sawing leaves you with less than 1/2 the width of the tree. My $0.02