Air Drying big slabs

[flht01]

Finally getting around to using the csm again and have a question. I'm slabbing a big water oak (about 12/4 thick slabs) with hopes of getting a couple dried worth using for table tops. These will be about 30" wide x 8 ft long. I had plans on sticker stacking like any other air dry stack with the ends coated. These thick slabs seem to split and crack a lot more than "normal" sizes, just wondering if anyone is doing anything special to help with the odds of getting better results.

 

[Husky137]

I would start with a lot of weight on top. Concrete blocks work nice for me.

 

[woodshop]

...you would need an AWFUL lot of concrete block to keep 3 inch thick 30 inch wide slab from moving.

I would do just what you are doing, coat the ends and sticker like other boards. Keep in mind that if it's anything like my 12/4 oak and sweetgum slabs I dried, it will take a long time to dry.

 

[flht01]

I'm planning on using it to make a couple of outdoor (porch) tables and benches. I'll let it airdry until this time next year and then try using it. I'd hate to guess at the drying time needed to reach 15 percent.

 

[WadePatton]

I'd hate to guess at the drying time needed to reach 15 percent.

I've been told one year per inch of board thickness...I may have to build a solar kiln.:jester:

 

[flht01]

I've been told one year per inch of board thickness...I may have to build a solar kiln.:jester:

Solar kiln is on my list, right after a bigger place to stack and store more wood. Running out of room fast.

 

[scottr]

Solar kiln is on my list, right after a bigger place to stack and store more wood. Running out of room fast.

Kevin , I would think the value of the thick oak slabs would justify building a dehydration kiln like the one in the 'wood and how to dry it book' .

 

[flht01]

Kevin , I would think the value of the thick oak slabs would justify building a dehydration kiln like the one in the 'wood and how to dry it book' .

Found the book buried in the bookshelf, looking now ...

 

[aggiewoodbutchr]

...you would need an AWFUL lot of concrete block to keep 3 inch thick 30 inch wide slab from moving.

I would do just what you are doing, coat the ends and sticker like other boards. Keep in mind that if it's anything like my 12/4 oak and sweetgum slabs I dried, it will take a long time to dry.

Hey Woodshop. Got any pics of those sweetgum slabs?

 

[aggiewoodbutchr]

Finally getting around to using the csm again and have a question. I'm slabbing a big water oak (about 12/4 thick slabs) with hopes of getting a couple dried worth using for table tops. These will be about 30" wide x 8 ft long. I had plans on sticker stacking like any other air dry stack with the ends coated. These thick slabs seem to split and crack a lot more than "normal" sizes, just wondering if anyone is doing anything special to help with the odds of getting better results.

I've had the best results keeping slabs flat this way...

The rods must be tightened periodically to compensate for shrinkage.

Otherwise, stack and sticker them like you and others said and add tons of weight. Yes they will check (particularly water oak) and all you can do is keep it to a minimum.

I urge you to resist the temptation to kiln dry thick slabs. Have patience and let them air dry as slow as possible as your results will be better. In my stock, there is a noticable difference in quality between the stuff I milled in cool vs. hot months.

 

[aggiewoodbutchr]

I've been told one year per inch of board thickness...I may have to build a solar kiln.:jester:

That is a very general, ballpark, rough, rule of thumb that attempts to average many, many, many variables.

I checked some of my stock last week with a meter. 10/4 pecan slabs I milled March '06 gave me readings of 16% +-1% which is close enough to EMC for my area for them to be used. If I followed the 1" rule of thumb I would be waiting for another year and a half. Even if I dried them in a kiln they will eventually equalize back to whatever the current weather conditions dictate.

I stole this from an undisclosed source. It may be useful to someone.

Q.
Can you post the equation or table that gives the equilibrium moisture content (EMC) for differing relative humidities (RH)? i.e., 10 percent RH = x EMC, 20 percent RH= y EMC, etc.

A.
0% RH = 0% EMC
19 to 25% RH = 5% EMC
25 to 32% RH = 6% EMC
32 to 39% RH = 7% EMC
39 to 46% RH = 8% EMC
46 to 52% RH = 9% EMC
57% RH = 10% EMC
65% RH = 12% EMC
74% RH = 14% EMC
80% RH = 16% EMC
91% RH = 21% EMC

The short form is:
0 = 0
30 = 6
50 = 9
65 = 12
80 = 16

Also, an approximate equation good out to about 80 percent RH is: EMC = 0.2 x RH

 

[flht01]

Thanks for the info, Aggie. Finally getting around to slicing that water oak, really suprised at some of the grain patterns. That 084 is a lot of saw but I'm starting to see why there's so much discussion on converting to 3/8 chain. That 404 makes a lot of sawdust.

 

[aggiewoodbutchr]

Thanks for the info, Aggie. Finally getting around to slicing that water oak, really suprised at some of the grain patterns. That 084 is a lot of saw but I'm starting to see why there's so much discussion on converting to 3/8 chain. That 404 makes a lot of sawdust.

Yep! Piles of it.

 

[woodshop]

That is a very general, ballpark, rough, rule of thumb that attempts to average many, many, many variables.

I checked some of my stock last week with a meter. 10/4 pecan slabs I milled March '06 gave me readings of 16% +-1% which is close enough to EMC for my area for them to be used. If I followed the 1" rule of thumb I would be waiting for another year and a half. Even if I dried them in a kiln they will eventually equalize back to whatever the current weather conditions dictate.

I stole this from an undisclosed source. It may be useful to someone.

Well said aggie... example... I have had some 4/4 cherry dry to 20% in 6 weeks, and then another cherry, same thickness but took almost 6 months. I have too much else going on, and mill too many different kinds of trees at different times to keep track of enough variables to nail it down what factors effect what exactly. If this is all I did, I might eventually get somewhere with that. Botton line is, the wood is dry when the meter says it is In general, 4/4 or 5/4 anything rarely takes more than 6-8 months to dry. Often only 3-4 months. But just too many variables.

You asked if I had any sweetgum slab pics. No, but if I did they wouldn't impress you much. I have milled sweetgum in the past... talking about this stuff...
http://www.cnr.vt.edu/dendro/dendrology/syllabus/factsheet.cfm?ID=53 and gotten beautiful reddish brown heartwood. Unfortunately, this particular tree that I milled last spring was almost pure white sapwood the whole 24 inches dia. Bummer. So got lots of hard solid homogeneous white hardwood boards out of it, but no beautiful colorful grain as I had hoped when I agreed to take the tree (before it was actually cut down). I might try and stain some of it and see what that does for me. Right now all of it, mostly 5/4, but several huge 12/4 slabs, are buried under a bunch of white oak I stickered on top of it. I'll pull the whole pile apart in the spring. By that time it should all be down to at least 20% at which time I un-sticker and store the wood away. As you can tell by your little fact sheet on MC and humidity, in the humid summer (here on east coast) it won't dry to much less than that no matter how long it sits there.

I felled a fairly large chestnut for a friend of mine late last fall but didn't get it milled before winter and other things got in the way. Plan on doing that soon, and will post pics of that when I do. For those of you who have never seen it, Chestnut is kindof a unique wood. It is often a beautiful light brown and has lots of squirrelly grain in the crotches etc. Should make for some nice milling pics.

 

[aggiewoodbutchr]

That's the sweetgum I was refering to. Bummer your's is plain as it is. I'll be picking up a few this Friday with some oak and pine. Pics will be provided, of course.

Chestnut, you say? What variey?

 

[WadePatton]

Yes, I'll be getting a meter. Good to hear that I might get to use some wood before the year is out.

Chestnut? I just posted about some pre-blight, lost-in-the-river, chestnut on my "Tennessee" thread. They're estimating that log to be from 150 years ago--with mineral staining from the water and all.

END/thread Hijack/END :greenchainsaw:

 

[woodshop]

That's the sweetgum I was refering to. Bummer your's is plain as it is. I'll be picking up a few this Friday with some oak and pine. Pics will be provided, of course.

Chestnut, you say? What variey?

As it was a huge tree, and looked pretty healthy, so I assumed it was a Chinese chestnut. I will attempt to ID it when I get up there and start slicing it into boards.