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Moisture issue?

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Forum topic by drewm873 posted 10-20-2017 05:05 PM 583 views 0 times favorited 15 replies Add to Favorites Watch
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drewm873

66 posts in 2343 days


10-20-2017 05:05 PM

Hi All,

So, I have an issue and I’m not sure if I should just burn all this lumber or give it time. Last year I posted this lumber I bought off of someone who had it milled and it sat in a barn for probably 5 years. Now, I’ve been trying to use this stuff but after it’s jointed and planed, days later it warps. Moisture in my garage is around 12%, with NJ weather, and the wood comes out a little under 12%.

Do I need to just not use this stuff and put a fan on it for a year? Or is this stuff just junk from being air dried wrong? I’m dealing with Maple, Oak and Cherry. The Butternut and Cedar are fine.

Frustration has set it, ready for the bonfire. lol

Here’s what happens with a glue-up:

Thanks!


15 replies so far

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Rick_M

10471 posts in 2193 days


#1 posted 10-20-2017 06:36 PM

Your link is broken
http://lumberjocks.com/topics/174322

Mill it as you use it, not days ahead of time, no more than 24 hours. There could be all sorts of reasons it’s moving but even perfectly dried wood will move some over time.

-- http://thewoodknack.blogspot.com/

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WDHLT15

1687 posts in 2289 days


#2 posted 10-20-2017 07:29 PM

Wood only moves if the the moisture content is changing. Stack your boards and put 1” spacers between the layers every 16”. Make sure that the foundation that you are stacking on is level. This allows air to reach all sides of the board. Never take a board that you are planning to glue up into a top or panel and lay it flat on a surface over night. One side get air, the top side, the other side, the bottom side, does not. Leads to uneven moisture distribution, thereby warp, twist, and cup.

-- Danny Located in Perry, GA. Forester. Wood-Mizer LT40HD35 Sawmill. Nyle L53 Dehumidification Kiln. hamsleyhardwood.com

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Andybb

523 posts in 417 days


#3 posted 10-20-2017 09:47 PM

NO! Don’t burn it. That’s a shit-ton worth of $ and good looking stuff. As Rick_M said, ”Mill it as you use it”.

Had the exact same issue. You need to sticker it if you aren’t gonna use it immediately after milling. Got great advise from this post a few weeks ago. All good now. Especially liked Rich’s pallet wrap idea. That piece in your pic is not too warped to be planed flat IMO. Plane/joint it and use it or plane/joint and sticker it.

Just pulled a few 1/2” thick ones from the stack and bookmatched them last night. Here in the PNW we went from 70 deg and dry to 45 and raining in the last week and they were still flat.

-- Andybb

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TheFridge

8137 posts in 1299 days


#4 posted 10-21-2017 01:07 AM

What they said.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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JBrow

1252 posts in 733 days


#5 posted 10-22-2017 02:22 AM

drewm873,

If the glue-up was flat at one time and then developed the cup, then I would say that too much moisture entered or left one face of the glued panel. This moisture imbalance allowed wood fibers on the face with greater moisture to swell to a greater extent than on the face with less moisture; causing the panel to cup.

As already mentioned, stickering glued-up and milled stock is the best insurance against these issues. Also exposing fresh wood on both faces during milling helps to maintain equal moisture exchange with the air.

I have had success returning a cupped glued-up panel to flat by introducing moisture to the concave side of the panel. In the posted photo, this would be the face to the left. I soaked the wood on the concave side with clean water and laid a damp, clean cloth on the concave face (to keep the side damp) with the convex face setting on a solid flat surface. After several hours, when the panel returned to flat, the wet cloth was removed. I kept an eye on the progress because if too much moisture is added the cup would be reversed. Thereafter I stickered the now flat panel.

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Andybb

523 posts in 417 days


#6 posted 10-22-2017 04:04 AM

I soaked the wood on the concave side with clean water and laid a damp, clean cloth on the concave face (to keep the side damp) with the convex face setting on a solid flat surface.
- JBrow
+1
Do you also weight and sticker the top side while it’s soaking? That is an awesome tip and worth the price of admission. Thanks.

-- Andybb

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Rick_M

10471 posts in 2193 days


#7 posted 10-22-2017 05:09 AM

They used to say, early in the morning leave it out on the grass convex side up. You get the double whammy of the morning sun and moisture from the grass. I dried some pine 2×8s and 2×12s by leaning them against my shop and kept rotating them. The sun would hit one side, board would bow, I would spin it around and an hour later it was bowed the other way. After a few days, they stopped bowing.

-- http://thewoodknack.blogspot.com/

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Andybb

523 posts in 417 days


#8 posted 10-22-2017 05:21 AM

Ah! Sage advice from the ubiquitous “THEY”.

-- Andybb

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JBrow

1252 posts in 733 days


#9 posted 10-22-2017 01:59 PM

Andybb,

I flattened the panel by placing the convex side directly on the workbench. It was in full contact with the workbench surface, although the panel did rock a bit. One of three things could happen if the convex side were elevated by sticker sticks.

The first is moisture on the convex face of the panel could exit the panel as moisture is introduced to the opposite face of the panel. If this were to happen, the panel should come back to flat quicker.

The second is no moisture is drawn into or released from the convex side of the panel. If this were to be the case, the panel would return to flat in about the same time as it would if the convex side were placed in direct contact with the workbench

The third would be that the convex side could draw in more moisture from the air. This would increase the cup and require more time to flatten.

Since I had no way of knowing which of the three would occur I elected to leave the convex side in direct contact with the workbench.

Once the panel is flat, it is stickered to allow air to flow freely around both faces. This should help keep the moisture exchange constant on both sides of the panel and thus keep the panel flat.

I only used this method once. Since then I made a number of stickering sticks and am very careful to keep freshly milled lumber as well glue-up panels stickered. As others have said, it does indeed help keep stock flat.

I did not add a weight to the moistened concave side. I wanted the drier side of the panel to absorb moisture into the wood fibers naturally, believing this would be the best method of ensuring the resultant flat panel would be moisture equalized on both sides. I feared the weight would fool me into thinking the panel had flattened out but once the weight was removed, it would retain a slight cup.

If you want to speed up the process, adding heat to the dampened cloth might drive moisture, in the form of steam, into the wood fibers quicker. While I did not use heat to hasten the process, I mention it because if a dent is found in a piece of project wood and the wood fibers are merely crushed, and not broken, steam can be introduced to the crushed fibers and erase the dent (the steam fills the crushed fibers causing them to swell). The source of heat could a clothes iron set no higher than that required to generate steam from the dampened cloth.

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Andybb

523 posts in 417 days


#10 posted 10-22-2017 06:06 PM

I did not add a weight to the moistened concave side. I wanted the drier side of the panel to absorb moisture into the wood fibers naturally, believing this would be the best method of ensuring the resultant flat panel would be moisture equalized on both sides. I feared the weight would fool me into thinking the panel had flattened out but once the weight was removed, it would retain a slight cup.

- JBrow

^ Excellent. Thanks for the detailed reply and the thought process. Makes sense. I’ll have to try that if I need to go on a rescue mission. It’s better than making already thin stock even thinner.

-- Andybb

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drewm873

66 posts in 2343 days


#11 posted 10-23-2017 12:41 PM

Thanks everyone for the sound advise and apologizes for the late response. This whole concept of working with air dried lumber is new to me but I’ll get the hang of it. I’ll save this post for some reminders later on when I need to reference back on stuff.

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TheFridge

8137 posts in 1299 days


#12 posted 10-23-2017 01:50 PM

If I forget a panel on a surface and it cups, I’ll put a fan on it or just flip it over and give it a day or two. Mostly I just stand it up and it’s fine. Depending on the application I may not even care.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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rwe2156

2689 posts in 1294 days


#13 posted 10-23-2017 01:57 PM

Yeah, its going to be a bigger issue with kiln dried lumber, but a lot depends on the sawmill and how it they are storing the wood.

The issues are

1) uneven drying
2) improper drying
3) internal stresses
4) the type of sawcut

Suggestions:

1) Mill evenly and lightly each session
2) Sticker and weigh down the stack
3) Be sure the wood is in a lightly ventilated area (no fans, off the concrete 6”, etc).

In some instances, a board will simply be unruly in these cases you can rip the board, joint and reglue.

-- Everything is a prototype thats why its one of a kind!!

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Carloz

869 posts in 405 days


#14 posted 10-23-2017 02:06 PM

I doubt that NJ ever had 12% humidity. It is rare even here in So California. 70% is more of the norm. I would question hoevewer someone’s claim that the wood was in barn for 5 years if it warps so badly now.

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Andybb

523 posts in 417 days


#15 posted 10-23-2017 08:41 PM

3) Be sure the wood is in a lightly ventilated area (no fans, off the concrete 6”, etc).

- rwe2156


Just out of curiosity, why no fans? Seems like it would aid in circulation between the stickers.

Not that it matters for this discussion cuz it is what it is but even Arizona averages over 50%

-- Andybb

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