# Drying thick trunk slabs



## bues0022

This weekend a buddy and I cut down a big burr oak on his land, ~40 inches diameter. The bottom of the trunk had some really nice grain to it, so we sliced a few "disks" from it. They are between 4-6 inches thick. I'm planning on making a few coffee tables from these big slabs once they dry.

That leads to my big question. How do I dry these? The tree was very green and alive, so they are just soaking wet. Do I wax them at all? stack and sticker them and put a fan on them? How long do I dry them for? I might have access to a friend's large furnace, but it'd bake them at about 140F, and I'm afraid if I do that then I would end up with cracked wood. I plan on doing a flattening cut on both sides just to flatten out some of the chainsaw irregularities (chain was getting dull on one cut, so it's awefully crooked), then final facing once it's dry.

Any advice on the best method of drying would be appreciated.


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## Doss

Well, let's just get this out of the way, you're going to end up with cracked wood regardless. If you understand the structure of wood, you'll understand what's going to happen and why it'll crack.

Also, that oven will dry them way too fast.

Your best bet is to save several disks that are in order and piece them together (woodglue) from the uncracked pieces. You may get lucky and have one that doesn't crack… but I doubt it. There are products on the market that can possibly stop this from happening, but not on a disk this large.

Some woods don't crack as much as other. Oak is not one of these. I had an oak disk go 4 months without cracking (24" diameter). One day I came home from work and it had opened up about 1" on the edge.

What is this flattening cut you're talking about?


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## WDHLT15

Put about 3 or 4 coats of anchorseal on each face. However, like Doss said, cookies crack, especially oak.


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## jap

but the crack can add character…in the right projects


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## grizzman

there going to crack, nothing you can really do to stop it, the anchor seal might help some, but…still gonna happen, you should coat them with some cheap oil base paint, sticker them, keep them in the shade and forget about them, check on them after a year to see how there doing, if there still looking ok, then forget about them for another year and then check the moisture and see where there at…


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## Dusty56

Basic rule of thumb is one year per inch of thickness on lumber. This will depend on species and drying environment. 
I don't know how much longer it will take to dry a cookie with Anchorseal coating it on both sides. 
Best wishes on the "not cracking". : )


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## Doss

Rick, I have mentioned Pentacryl before but didn't bother mentioning it here b/c I really can't vouch for the success on something this large and possibly unruly.


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## Doss

Rick, are you in bot mode?

I know what they state, but they also state "oak". The characteristics of all species of "oak" are not the same.


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## bues0022

I maybe should have been more clear with my cracking point. I had dried some pieces in my friend's oven previously, and when they cracked, the board essentially split in two. Some radial cracks will not make me loose any sleep, as long as the piece doesn't fall in half. As some mentioned, the cracks can give character. Depending on the size, I could epoxy them, or put in a bowtie, inlay some turquoise, etc. Lots of options.

I was looking for the most effective way to dry these pieces. It looks like I'll have to clear out a spot in my garage, stack and sticker them. I'll look into coating the surface to help keep cracks to a minimum, but it will happen, such is life.

How would these kiln dry? Kilns don't take an inch per year, right? Is there any safe way to rig something up to help them dry faster? I know I won't be working these any time soon, but if I can do something to these so I can work them in a year instead of two it might be worth it.

My "flattening" cut = I have a router sled made so I can flatten out large pieces of rough-cut lumber. (poor-mans giant planer) For example, one cookie is 6" thick on one side, and 4" on the other. I can hog off a bunch of material, bring total thickness down to 4" to help it dry. It won't stay completely flat during drying, so after dry I'll face it again to make it flat.


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## Dusty56

6" thick on one side, and 4" on the other. 
I would attack that with a sharp chainsaw before trying to route that much material off : )

safe way to rig something up to help them dry faster?
I just used an old 20" box fan to keep the air circulating around the last wood that I air dried. 
It was in my garage ,not outside : )


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## bues0022

It's a "lip", and I figured it wouldn't be that but, but your suggestion is noted. I'll be back out there this weekend and might try that first. Good idea.


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## Doss

Yeah, I didn't know what you were talking about with a flattening cut. I thought you were about to try to chainsaw a piece flat. LOL

I use a router sled for my slabs by the way. It's effective enough. I have 6.75" power planer to help knock it down quickly though.


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## WDHLT15

Wood dries fast from the end grain. A fan on oak will probably make the cookie dry too fast, and it will split worse. Slow is good with oak. Most kilns will not dry those cookies. Takes too much time.


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## RussellAP

How did you cut these slabs? Are they vertical rings or horizontal? How thick are they? No matter what, it sounds like you're going to be letting these sit for at least a year before they go to the kiln. Some will crack, but that's life, just saw it off and use what's left. Most of us who buy rough cut are used to the waste, but we get a great price on wood that way. 
If they are still wet there is some stuff you can put on the end grain that will help, but my sawyer doesn't mess with it.


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## bues0022

How much surface area does a quart of Anchorseal cover? I can't seem to find it online. I have just over 6000 square inches to cover (42 square feet). Will one quart be enough to soak in and coat all surfaces? Will a parafin/minera spirits mix do the same thing? (cheaper)

I am also wondering about location to dry them. The most convenient is my friend's garage/shed that is only heated from time-to-time over the winter when he's out there working. Otherwise it's pretty frozen (MN winters). Should I talk him into keeping them inside his house in his basement? Keep them frozen all winter out in his barn? What's the best condition to dry them under?


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## Doss

Does it really go down to freezing in the garage? If so, that's probably not a great place for them.

I found some info that said a quart of Anchorseal covers 25 sq ft.


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## bues0022

It's a detached garage, so it definitely freezes hard when he doesn't have the heater on.


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## bues0022

I found that site earlier, but it looks rather expensive.

I read somewhere about a 50/50 paraffin wax/mineral spirits mix - thoughts on effectiveness? Or by the time I buy everything and mess around with heating etc. will I just be better off with the anchorseal?

(anyone in the Minneapolis area know where the best deal is on this?)


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## WDHLT15

Anchorseal is the best stuff. It is designed to do just what you want to do. Get the original formula, not the green formula. You have to call them to order it. UC Coatings. There is no instant pudding.

Drying green oak in a heated space is asking for trouble.


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## chopsticks1

Can you use both Anchorseal and Pentacryl on same piece? Which would go first? Anchorseal? Also, if drying outside, does a hard freeze in the winter crack the wood? I read you can seal and then cover with plastic to keep it like it's soaking in sealant…any thoughts. thanks


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## bues0022

What we ended up doing was coating cut edges with anchorseal, and now it has sat in an attached tuck-under garage for two years. In another couple it might be ready.


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## rick1955

http://www.preservation-solutions.com/wood-preservation-treatment-products/wood-treatment-product-guides/stabilizing-a-cross-cut-section-of-wood-with-pentacryl/
Here's the instructions…


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## chopsticks1

I have seen that page, thx


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## Ocelot

The only thing I've heard of that might keep such a thing from cracking is to soak it in PEG (polyethelene glycol). The PEG will replace the water in the matrix of the wood so that the wood does not shrink and crack. Archeologists use it on old ship timbers they find in the sea. Woodturners use it to stabilize green wood. You can buy it at Rockler and other places - including Amazon.

http://www.rockler.com/polyethylene-glycol-peg-green-wood-stabilizer

Instructions here
http://go.rockler.com/tech/RTD10000%20812.pdf

A quote from the instructions :
"Even large treated disks, 4 inches thick by 40 inches in diameter, will dry in six to eight weeks in a heated room." (after soaking in PEG for the recommended time).

I've never used it, so I can't say that it would work for you. It sounds like you would need a *lot* of it, so it may not be economic.


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## splatman

To limit the amount of PEG (or whatever) you'll use:
Build your soak tank 2" larger and 2" or 3" deeper than their thickness. A flexible plywood ring attached to a plywood 1/2-sheet on a table will do. Line it with a few layers of plastic sheeting. Place some small wood blocks on the bottom, to raise the disk a 1/2" or so.


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## OldWrangler

Something I had good luck with several years ago. I had a big round slab of Walnut, 22" in diameter and it was green. Even being only 2" thick it weighed a "ton". I got a strap hold down with the rachet crank (the kind like you use to anchor a motorcycle in the bed of a pick up). Put that around the outside and crank tight until it won't tighten any more. Then coat both open sections with a good soak of Minwax Wood Hardener. Just pour it on and spread it before it is absorbed. My Walnut never cracked and I was able to use it for a lazy susan a year later. I just put it in a dry spot out of the sun and covered with saw dust or shavings. Mine I set in a box like a pizza comes in covered with shavings and put it in a corner of my garage. But this was Walnut and not Oak but really worked. An old carpenter suggested it. He passed before I could learn his whole big bag of tricks.

One of his favorite educational tidbit was "table legs don't have to be the same, they just have to look the same. Since you never see them all close to each other, they can all be a little different.


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## rick1955

Pentacryl has replaced PEG and it does work. Some friends wanted dry some "cookies". They dried them with no cracks or splits. PEG is waxey and you can't put a finish over it. With Pentacryl you can.


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## Ocelot

I like the ratchet strap idea! I would think you could go tighten it every week or so for awhile.

I didn't know about pentacryl. PEG, I have read, does limit your choice of finishes, but there are some that will work.

Also, to limit the amount of PEG (or whatever) you need, you can add smooth rocks etc. which will raise the liquid level but not absorb the stuff.


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## chopsticks1

Good to hear everyone's opinion/experience. Thanks.


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## chopsticks1

Is there something you can spray on bark to preserve it on a cookie?


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## SolracChiselJunkie

I've only done this a few times. One way, paint the end grain and let it sit. Like everyone else has said, let it sit somewhere with shade and good air movement, if your shop doesn't get to cold or hot keep it inside, and keep it off the ground or floor, by a few inches, so air passes under. Now let it sit there for two years. Yup, takes a while. The ones I've done ended up at around 6-8 inches thick once I planed them down with my router. After sanding them in my shop I sealed top, bottom, and all around, with waterlox. I seal it with two coats of the waterlox, then start the poly. I poly many coats all around it and the top. I also epoxy any little cracks or holes, ANY LITTLE CRACKS, this is important since it goes in and seals them. It's time consuming, and you might have to do I few times. So far I've done this with maple, and all the pieces are just fine. I've inspected them and there a few tiny new cracks, but only I notice, and I'm mkt even sure they are new or maybe I just missed them.

My second method I'm now experimenting with to cut down on the dry time is to cut your discs from the log and SOAK them in denatured alchohol. I used probabaly a gallon worth of it per 20 inch wide disc, 5 inches thick. In two days the outside went from reading 30% moister to 17%, and really only minor checking. I've already planed them even, to 4.5 inches. I experimented and took a piece out of my workshop and put it in a air conditioned room, only two days after using the alchohol, and they still had a lot of moister in the middle, so it is cracking out, but not splitting apart. The rest in my shop are still just fine, no cracks or splits. I think I need to keep them drying there for a year and then do my waterlox and poly, and that will cut my dry time in half essentially.

My final solution, which I haven't done yet, but a friend who welds will help me, is to make a metal band that goes around the piece, so if it cracks or splits it will stay together with the metal bands.

Hope some of this helped.


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