Drying lumber, FAQ type questions

[slowzuki]

Ok, I've done a few searches and haven't found anything yet!  I have some basic Q's:

Why do people paint the ends of logs before storing them?  Is this to keep them from drying faster than the middle?

What is wrong with slowly drying a log over time vs kiln drying?

If slowly drying, is ok, how slow is slow? Ie shaded, no wind or sunny and windy or room temp?

How long can a tree sit outside before milling if kept off the ground and sheltered from rain? (I guess specifically I mean spruce)

Is white/eastern cedar usable in timber framing? Other than the larger timber sizes required, is there other problems?

Thank, I'm sure some valuable answers are out there!
Ken

[IndyIan]

Ken,
Here's a link you will like, being an engineer, if you haven't found it yet.

http://www.fpl.fs.fed.us/documnts/FPLGTR/fplgtr113/fplgtr113.htm

It gives all lab tested properties for many types of wood, green and dry.

I have a white spruce tree that's been down for just over a year that I hope to mill soon.  Its off the ground but not sheltered at the edge of the woods so it gets a bit more airflow to dry it.  I find most softwoods have the sap wood go punky first and then the heart wood.  If you just need a beam and can cut it without getting into sap wood you could use some pretty ugly logs.  

I own a couple slowzuki's too.  We have a 2001 Kingquad(my skidder ) not much horsepower but gears and a dif lock to make up for it.  Also we just bought a 2003 tracker, 4cyl, 4x4, 4dr, 5spd.  Not much hp either but still fun in 4 low.  

Ian

[jeepman]

Slozuki,
I'm no expert, but it's raining and I'm sitting here so here's my $0.02 worth.
1. We end coat to keep the bugs out and let the log dry more evenly.
2. Slow drying is preferred (fewer checks and more stable wood) besides the other problems associated with trying to get logs kiln dried. Remember, they will dry slowly anyway (1 year/1 inch). Most people frame with green lumber.
3. I prefer shady/windy for air drying timbers. The sun will dry the surface to fast.
4. The time outside depends a lot on the weather. You'll probably want them to sit around for a couple weeks anyway to let the resin dry up a little. If they are going to lay for a month or more, I'd peel um to keep the grubs off. The longer they lay around, the harder the wood gets and the harder they are to mill.
5. I don't have any cedar so I can't offer any help there.
These may not be valuable answers, but they're a start.

[Den Socling]

My experience is with hardwood, only.

You end coat logs to reduce drying. A log dries fastest at it's ends. If you dry too much, it cracks. Even if it doesn't crack, lumber from the end will have lower moisture content at that end. This leads to cracking in the kiln.

One problem with very slow drying is discoloration from mold and fungus. Insect damage is another problem. If you try to dry a log until the center is down to, perhaps 15%, you are looking at years of drying.

[Jim_Rogers]

If a log is to be milled into a timber or boards what is the point of trying to dry it first?
Why spend all that time/money drying the waste? What is the purpose of drying the slab or sawdust?
If the log is to be a timber, mill it into a timber and if you want that timber dry, then dry it.
The bark on a log attracts bugs, the bug lays an egg, the egg hatches into a worm and the worm eats the wood. Why take the risk, remove the bark, by milling the log into a timber, even if it's an over-sized timber, you can alway re-mill it later to the correct smaller size. But this will only remove the outer drier wood and now you've got a green timber again.

As mentioned most timber frames are assembled with 'green' wood, whether that green wood is surfaced four sides or not.

The "paint" put on the ends is usually a wax product that seals the ends of the log, which is then converted to a timber, and that forces the water to evaporate threw the faces of the timber not the ends. If it evaporates out threw the ends the ends shrink and therefore cracks.

Softwoods such as spruce attract bugs during warm weather. If the log is cut after bug season it can sit for quite a while, like until spring, but once the bugs are out then they are looking for the bark/log to start the whole cycle over again.
Around my area any log that has sat threw a summer is considered junk, or a least very low grade, as it could have bugs in it.

And as mentioned most beams are made up of heart wood, but some sap wood around the edges are sometimes acceptable if they aren't discolored, which is what can happen to the wood if the fungus gets to it.

As to your question about white/eastern cedar being used for timber framing, I'm sure it can be if it's used within it strength properties. What I mean by that is that you'll have to figure out what load will be placed on the timber in it's intended use location and see if this type of wood can support that load. If it can't then I wouldn't use it. In designing a timber frame each timber has to be sized based on it's use. This sizing also includes the type of wood to be used.

When lite colored woods age they darken and dark colored wood lighten with age. If this cedar is very light colored you should consider using a UV protecting stain on it, if it's in a house, and you want to base that on it's location in the frame. Will it be in the sun? or in the roof and never in the sun.

Many timber frames have been made up of different types of woods. What I mean to say is that you can mix types in the same frame if you plan on the shrinkage differences.
Understanding the shrinkage differences and planning your joinery to compensate for these shrinkages is a challenge to say the least.

The only other thing about white/eastern cedar would be the appearance when dry. It depends on the frame's intended use, are you just building a barn or out building or a house?
Appearance in a barn isn't consider that important, but in a house it is. What does white/eastern cedar look like dry? I'm not that familiar with it so I don't know if it would be a nice looking beam or not. I do know that light colored woods darken and you might have to use something to maintain that nice white look.

Good luck with your project and keep asking questions.
Jim Rogers

[slowzuki]

Thanks for all the tips.  Roger, I should give some background.  We have 40 acres we just purchased, the surveyor made a few mistakes running lines and ended up cutting down 3 really big spruce trees.  We plan on building a shop and a house soon.  The shop will be in the the new year or next.

I have no mill so we will be borrowing a friends.  I guess I will haul those trees out this winter for milling in the spring.

[Don P]

 One reason for drying boards rapidly is to reduce cupping. Dry wood is twice as strong as green, if you can hold wood flat and put a hard dry shell on it pretty quickly it is more likely to stay flat through the shrinkage stresses during the rest of drying. Fast drying reduces the likelyhood of fungal or insect attack.
Too fast and the shell shrinks too fast around the still bulked up core and the wood checks, like a fat boy busting his buttons when the jacket shrinks .
 Its best done when you can keep the drying rate between the ditches of too fast or too slow, things go south as you approach either ditch. You will see too slow as mold, you will hear too fast as popping and checking.

[etat]

I have a question.  Please don't anybody take this the wrong way, because I don't know, one way or another.  I have heard a very famous, or infamous, I'm not sure, Dr. make the statement that one inch per year is a myth.  Does anybody know why he would say this?

[Jim_Rogers]

I don't know why he would say this but I would ask him if he has said this to back up the statement with evidence or research that proves his statement to be correct.
I've had dealing with a certain Dr. on "another forum" and when I made such statements he called me on them and asked me for evidence to support my statements.
Now, I don't have any concrete evidence to say he's wrong but in the book: "Wood and How to Dry It", put out by Fine Woodworking on page 82, in a story by Paul Bertorelli an editor for Fine Woodworking magazine, he stated in his first paragraph of the article, "Conventional wisdom recommends air-drying green stock for one year per inch of thickness."
Having heard this same thing from the old timers who taught me about lumber seemed to support his statement and article.
If the Dr. has new research or new evidence to the contrary, I'd ask him to provide us with the information and set this myth straight.
Next, I haven't taken this the wrong way and I encourage your question, it's a good one.
But, I feel it would be better to ask the "Dr" to back it up with proof.
I've told you where and who I based my statement on. And hopefully he will also.
If he does let us know so we can all be enlighten.

Here is a shot of the cover of the book I'm using as a reference:




Jim Rogers

[etat]

Jim, thank you for your very informative response!  That's one big thing I like about this forum.  It is inhabited by true professionals who give honest answers and try to help rather than just biased opinions from someone who thinks he is above everyone else.. If someone doesn't know something they can ask it here without getting hammered or belittled for not knowing. If one has a unique idea that they are wondering about, folks will kick it back and forth searching for a answer or a way to make it work.  Beneath the humor, fun, and stories here there is a invaluable wealth of knowledge. I have no need to go anywhere else.  I'm glad I found and am a part of this forum.  Thanks!

[woodmills1]

I think I have heard the response to the one year having to do with the majority of drying occuring during the warmest part of the year.  I do notice that with much of the pine I cut, a few weeks in spring or summer will cause the boards to loose a lot of their weight.  With hardwood, especially oak you must be carefull during very sunny days to not let them get too hot or else you will see surface checking.

[OneWithWood]

I think the 'one year one inch' is a good general rule of thumb.  Drying time will vary by species as some species cell structures lock water tighter than others.  

[Don P]

I'm making the Christmas visiting loop and at my mother in laws playing on our old computer...my favorites are still on here...

The publication "Air Drying of Lumber" is at the link below, the whole thing is worth reading well.
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr117.pdf
Chapter 3 starting on pdf pg 25 explains factors that affect drying rate. I think pages 27-30 are what you all are looking for.
The old copy of this pub is at:
http://www.fpl.fs.fed.us/documnts/fplmisc/rpt1657.pdf
There are some changes, page 59 shows a sticker jig

One more document, " Estimates of Air Drying Times for Several Hardwoods and Softwoods"
http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr121.pdf
Although not named in the title some guy named Wengert is a contributor  ;) ;D

[Jim_Rogers]

Don_P:
Thanks for the link to the publications. I save two of the three to my computer, now I have to find time to read them.
Happy Holidays.
Jim Rogers