damage in air drying

[Den Socling]

I visited a customer today. They say their inventory stays around 6 million boardfeet of Red and White Oak. I was looking at 1000's of bf of stickered, 4/4 RO sitting in the sun so I strolled over for a look. The end checks were terrible. I wandered on over to one of the many drying sheds that are stuffed with 8/4. The outside packs had bad end and surface checks. These guys do beaucoup business. They have the place paved and ride from the office to the various buildings in a golf cart. They sure look very successful.

Later, I asked one of the middle level managers how they can stand all the end checks. He says they are no problem as they are gone before the lumber is shipped. I asked how much do they trim off. His reply, often none. The end checks close in the kilns.  :

[WoodChucker]

Wow, that sure goes against everything I've heard about drying lumber. I sure wouldn't think the end checking would close back up, but who knows, maybe it does. But it would still be there when you used the boards for woodworking and would need to be cut off. Shame a place that big wouldn't take the extra steps to do it right.They must be doing something right to be that big.  

R.T.

[Den Socling]

You can close checks and, if you do it right, they won't be 'bottle necked'.

I was kinda shocked. Like I said to my son, we have been working with squares and dimensions too long. Every crack, open or closed, comes back to haunt you if the square is heading to a lathe.

[WoodChucker]

Den, if you started this new thread because you feel I high-jacked your other one, I'm so sorry, I didn't mean to do that. I guess I got carried away with my own questions and forgot it was your thread. I'll start a new one of my own.  :-[

R.T.

[Den Socling]

I don't believe there is such a thing as hijacked threads. When the topic changes, as it will, start a new thread. They're cheap!  :D

[WoodChucker]

OK thanks, but still, I should have used better judgment and not turned into a motor mouth, I tell my wife she's one all the time and then I do it. lol.

R.T.

[Jeff]

Did someone call for a topic trasher? ;) Dont never need to apologize on this forum for altering the topic. It'll come back around jest like a rabbit. If it don't, stomp anudder brush pile. Ya'll know I'm the worst one for screwing up a thread. Now lets get this one back on track at least.

I prefer a beagle. They can get in and out and are huntin fools.

[Norm]

Problem with beagles is once they are on a scent they will pay attention to nothing else. Our late beagle KB (killer beagle) loved to chase rabbits so much he'd get a raw spot on his nose. He followed a trail across the highway and got hit but died doing what he loved.

Air drying gets a bad rap, an open shed or outside with not much else but a cover is not going to work. We try to cut our oak in the fall or spring before temps get too hot. It's stickered and stacked inside of our morton style building that is kept closed up year around. I don't put a fan on it until the moisture has come down, a little white mold doesn't hurt it. Drying too fast does, especially at first. White oak seems to be the worst to air dry of any we cut, red oak is next. 8/4 white oak right into the kiln would be a challenge, those first weeks would have to be monitored pretty closely.  

As with kiln drying careful air drying in the first weeks is important but to say most problems come from it is not always the case, I've seen plenty of wood ruined in a kiln. As a woodworker I still prefer air dried wood that has been done properly.

[Jeff]

I think 9 out of 10 beagles are named "Tippy"

Will surface checks caused by air drying close back up in a Kiln also?

[Den Socling]

Yes. Surface checks should close. But, if they are too deep and not closed properly, they will look like honeycomb.

[beenthere]

And the fact that they (surface checks) can close (they won't heal however), means that the buyer cannot see them and may only discover they are there when in a finished piece of furniture, or other product. There can be an argument made that the surface checks (if not progressed to honeycomb) will plane out.
No doubt about it, oak needs to be cared for from the minute after sawing, until its dry. Sometimes wonder if spraying with water after sawing will help surface checking problems. It would help limit the immediate surface drying when on top of a pile of wood, possibly.

[Den Socling]

Beenthere,

One of our customers covers all freshly cut oak that isn't making it into a kiln with shipping quilts every night. They claim it works. For longer periods, they dip it and wrap it.

The 8/4 oak that I was looking at on Friday looked OK if it wasn't in the outside packs. The drying sheds were simple, metal roof, open sides and closed ends. On some they dropped shade cloth from the eaves. These sheds combined with waxed ends were working fairly well.

Den

[jimF]

I can not give you a percentage number but a great deal of surface checks in oak are initiated on the green chain and it's stacks.  With the breezes and sun on oak for a few minutes, surface checks get started.  Spraying it with water after any drying of the surface will make it worse.  The surface will quickly swell and be compressed by nonelastic strain.  Then when it is redied (seemingly continued drying) the surface will shrink more than normal and the surface checks will get bigger and deeper.  This is the same that occurs in the air-dry yard on damp mornings because air-drying is uncontrolled.  Some think  by putting steam in the kiln initially you can increase the rate at which heat enters into the wood; drying the  wood faster.  This does the same thing and increases the surface checks.
Shipping blankets would be a good idea because it does not add water to the wood just slow it down.
Someone did a study of preplanning before drying.  The theory was that the surface checks were initiated by the sawtooth markers and removing them avoided the surface checks.  Theoretically this is reasonable within the field of study called fracture mechanics.  I think they did not consider the surface checks that occured on the green chain which they removed during the preplanning.  It only takes minutes in the sun and breeze for them to start.

[beenthere]

Jim F said  ""Spraying it with water after any drying of the surface will make it worse""

My thought was spraying BEFORE any drying of the surface, and then the wet blankets to maintain the moisture, and limit the sun and breeze affect on starting the tiny surface checks. I didn't make that very clear, and don't even know how practical that would be, but stopping the checking is money in the pocket (I would think). Surface checking may just be a fact of life too.

[etat]

This is strictly an unproven opinion.  I mentioned it once before.  I think spraying the wood with antifreeze will slow down surface drying.  I needed some 6inch by 6 inch pressure treated lumber to dry without cracks.  Obviously my first attempt was a failure.  The second time I coated with antifreeze..  This slowed the drying of these timbers tremendously, and greatly, greatly diminished subsequent checking and splitting.  As I stated this was on soaking wet pressure treated pine.  Cracks and checks in this wood is very minimal compared to my first attempts.

[jimF]

Most 6X6 treated timbers are heart-boxed, meaning the pith is included .  And treated timbers have nbeen dried before treatment - producing checks already.  Such timbered are impossible to avoid all checks.  So if you reduced the amount, you succeeded.  Antifreeze is ethalene glycol (EG).  PEG is poly ethalene glycol, a bunch of antifreeze molecules strung together.  It is sold to reduce checking.  It replaces water in the cell walls where shrinkage occurs.The longer the chain of EG the less it will evaporate.  So the long PEG replaces the water and will not let the wood shrink.  With anitfreeze, it also replaces the water but what does evaporate allows less shrinkage because the chemical bonds between the wood and EG are weaker than water and wood.  So when the EG evapoates it pulls the wood together less.  A disadvantage of EG is that it is poisonous.
Someone also has studied useing a diluted solution of Elmers glue.  It showed two things: that it does help.  And accidently a second goup of samples were coated the next day, the surface dried.  This group was worse because it rewetted the dry surface.
While it is difficult to avoid all checking it is not a fact of life, Maybe just a fact of business.  I think adding water before any drying before putting on blankets is unnesseccary.  You do want some drying, slow and controlled.

[beenthere]

Jim
How do you treat wood with PEG (poly ethylene glycol)?  

[Den Socling]

you have to mix a solution of PEG and water. Then you soak the wood in the solution.

[etat]

jim, thanks for the explanation.  I did know that antifreeze was poisonous so I took precautions.  I THINK that after it dries it presents no problems.  Also I knew that the wood had been dried, and rewet.  I felt that if I could make it dry slower it would be less prone to get those big cracks in it.  I also knew that to completely replace the water with peg would be practically useless in my case, as I understand it takes months.  What I was trying to do was to slow down the surface evaporation.  Pieces alongside the ones I treated dried, at least on the surface very quickly.  The antifreeze would keep the would damp for 3 to 4 days.  I didn't soak it in a solution, I just brushed it on. Also I cut the pieces to length and waxed the ends. I was basically just trying an experiment and perhaps got lucky.  

[MemphisLogger]

Goin back to Den's hijacked topic . . .

The 2 big commercial kilns I use here in Memphis sound like the one that Den described.

I was horrified the first time I took them a load of White Oak that I had carefully shade dried down to 20% and they threw it into an automatic stickering machine and put the resulting stack in the middle of their shadeless yard to wait for the next WO charge--with NO cover. Then I noticed that none of the oak in their yard had sealer or covers on it.

Since then I recommend to all my customers that intend to use these kilns that they air dry their oak at home before taking it to the kiln.