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How can I keep already dried wood from checking?

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Forum topic by thedudeabides posted 03-19-2010 03:27 AM 996 views 1 time favorited 9 replies Add to Favorites Watch
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thedudeabides

75 posts in 1792 days


03-19-2010 03:27 AM

Okay, so I’ve got a bunch of 4×4 beams of mahogany that I bought kiln dried. I am making a butcher block island top so I cut them into cubes three inches thick and the cubes immediately checked to hell. So I left the uncut beams further air dry all winter in a controlled, low humidity environment. Now, six months later I tried again and the damn things are still checking like Bobby Fischer.

I know checking is the result of uneven moisture loss in the wood, but I can’t seem to stop it from checking, even after the moisture meter says it’s 5%. Any ideas?


9 replies so far

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Michael Murphy

448 posts in 1657 days


#1 posted 03-19-2010 03:39 AM

4×4 is pretty big. What was the original MC. It may be that when you cut them to the 3 inch length the shrinkage is catching up to it, if that makes sense.

5% seems pretty dry.

Try getting the MC up to 8 in one beam before chopping it up and see if it doesn’t end check to a lesser extent.

-- Michael Murphy, Woodland, CA.

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thedudeabides

75 posts in 1792 days


#2 posted 03-19-2010 03:42 AM

I bought the beams at 8%, kiln dried. You think introducing additional moisture to the uncut beams would alleviate the checking?

View Gofor's profile

Gofor

470 posts in 2439 days


#3 posted 03-19-2010 04:18 AM

Checking is usually caused by high moisture wood drying too fast. Normally, the damage is caused by drying too rapidly when the wood is above 20% moisture content, although the damage may not be seen until it dries further. I think you either have wood that was dried too quickly, or wood that is severely stressed (i.e. grown in an area subject to high winds, or grown on a hill side). The severely stressed cracking is usually called wind shakes, not checking, and there is no cure for it. Likewise, wood that was originally dropped from original content to below 20% too rapidly can rarely be salvaged.

If your moisture meter is accurate, the problem is stressed wood. Does it read 5% when stuck into the newly cut face? Try it on a piece of green wood. Check the outside and then a fresh cut inside face. I hope your meter is inaccurate or has a low battery, and that the wood is not yet cured.

Normally, stressed wood will crack from the ends of the grain when it is cross cut instead if from the outside to inside. Where is your wood cracking?

Either way, I would definitely complain to the supplier.

Go

-- Go http://ncwoodworker.net/pp/showgallery.php?cat=500&ppuser=730

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Todd A. Clippinger

8775 posts in 2751 days


#4 posted 03-19-2010 04:33 AM

The wood checks because it is 5% mc on the outside and probably as much as 10% on the inside.

I have been working with doug fir beams left over from the construction of a timber frame home to build rustic office cabinetry. The moisture content on the exterior can be far different than the interior. I have been dealing with this as I literally am drying the material in my shop to use it.

Here is a moisture content reading taken on the outside of the beam 5×5 beam that I ripped open-

SV103004

Here is the moisture content reading taken from the inside of the freshly ripped beam just on the other side of board from the other reading-

SV103002

To see more about this situation that I have been dealing with in an ongoing basis see my blog the American Craftsman Workshop. I talk about monitoring moisture content and dealing with taking the material down in stages to stabilize it.

The job time line is being dictated by how well the material dries and stabilizes. All I can do is nurse it along.

-- Todd A. Clippinger, Montana, http://americancraftsmanworkshop.com

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thedudeabides

75 posts in 1792 days


#5 posted 03-19-2010 04:48 AM

Todd, I just ran the meter and you’re right. It’s a nice healthy 5% on the outside, but if I slice open a beam and plug the meter right into the heart of the beast it’s coming out at 14%. There’s the problem. It starts to check almost immediately and I’ve now got some really nice mahogany firewood for those special nights. So the answer is to just let the uncut beams continue to equalize?

View Todd A. Clippinger's profile

Todd A. Clippinger

8775 posts in 2751 days


#6 posted 03-19-2010 05:45 AM

You can seal the ends to slow the drying rate. But do not seal them perfectly, I usually spray a couple coats of rattle can lacquer or paint on the ends of stock to slow the rate. The end grain will soak up a lot of it and so you are not trying to get a perfect coat, just slow down the rate of water wicking out the end.

I have had good success with this because when I am in Ohio I can pick up material cheap compared to what I pay for it in Montana. The problem is that the ambient humidity in Ohio can be anywhere from 85% to 100% in the summer.

When I get the material back to Billings, it starts checking right away because ambient humidity levels of 15% to 20% are common in my area. I have a couple of hygrometers in the shop and watch them so I know what is normal.

The extreme drop in humidity causes the boards to start losing moisture fast so they check. I control it by shooting the ends of the boards with anything that is available. I almost always have a rattle can of lacquer available and it dries super fast. I have also used Krylon paint, brushed on latex paint, and acrylic clear coat with success. But that has been my personal experience

I also take the material down in stages. That means I don’t cut it down to the target dimension all at once. I always leave the material oversized. Cut open and let rest. Cut open and let rest. Then the final oversized pieces dry for the last time and you can mill to the final dimension.

The blog I did really documents the journey of cut and rest, cut and rest. But I have not sealed the ends of anything that I am working with now.

-- Todd A. Clippinger, Montana, http://americancraftsmanworkshop.com

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Todd A. Clippinger

8775 posts in 2751 days


#7 posted 03-19-2010 05:51 AM

You may be wondering if the material I pick up in Ohio is kiln dried and the answer is yes. It can test at 8% but when I bring it to Montana it starts to move and dry out even more.

When I buy material locally I let it acclimate a few days and then peel it open lightly and pre-cut a lot of the stock to oversized lengths. Then I let it rest. Anything that is going to move usually reveals itself in a couple of days.

I always have overlapping projects with my business so I am not really waiting on the wood to dry, it is in the shop acclimating and waiting for me to get to it. That is how it works out with my schedule.

-- Todd A. Clippinger, Montana, http://americancraftsmanworkshop.com

View John Ormsby's profile

John Ormsby

1279 posts in 2389 days


#8 posted 03-19-2010 06:56 AM

I have used Nelsonite for many years to stabilize wood. There is a recent product that I recommend one use if they are trying to keep fresh wood from checking. Nelsonite is toxic and must be handled carefully. This latest product does not have the high toxicity associated with other stabilizers. It is called Resolute.
I have used these stabilizers for many years on exotics, domestic hardwoods, and softwoods. I have never had a single board or block of wood check. One other note. I always store my green woods vertically. This is an old method that works well and keeps wood from checking during the air drying process. Your wood will reach your desired M.C. much quicker with this approach to drying.

Here is the link to the only supplier: http://cuecomponents.com/nelsonite.html

I am not affiliated with them. Just like their products and wood.

-- Oldworld, Fair Oaks, Ca

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DryingProtection

9 posts in 497 days


#9 posted 08-22-2014 08:02 PM

Has anyone tried Bates DPS—- a dried parts stabilizer? water-based non hazardous

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