iDRY Vacuum Kilns

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may be interesting

Started by Den Socling, June 20, 2006, 05:32:50 PM

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Den Socling

I sometimes get samples from far off corners of the earth and I needed a head start on deciding how difficult they will be to dry. So I set up a microscope. Thought some of you would like to see why one tree 'acts' so much differently than another.

These are all at 20X.


That's easy-to-dry red oak.


That's fairly-easy Shagbark hickory.


That is the little-more-difficult white oak.


That is the surprisingly difficult Eucalyptus grandis. This piece from Uraguay.


And the mother of difficult-to dry species, red beech from New Zealand.

Tom


Den Socling

Why? Why what?  :D Why do they act differently. DanG but I thought it was obvious. Some look like sponge cake and some ...... is your hand up, Tommy?  :D

Deadwood

I've tried to air dry Beech before, American Beech and I tell you it is far easier to herd a hundred Basset Hounds in a straight line than it would be to get straight, flat lumber from Beech. Great wood to work with mind you, just very, very difficult to dry.

LeeB

Never dried beech wood before, but the picture in my mind of 100 Basset Hounds makes me not want to. :D LeeB
'98 LT40HDD/Lombardini, Case 580L, Cat D4C, JD 3032 tractor, JD 5410 tractor, Husky 346, 372 and 562XP's. Stihl MS180 and MS361, 1998 and 2006 3/4 Ton 5.9 Cummins 4x4's, 1989 Dodge D100 w/ 318, and a 1966 Chevy C60 w/ dump bed.

getoverit

It seems that the larger the "water pockets" are in the wood, the easier it is to dry??  Noticing that the red beech doesnt even have any visible water poclets at 20x magnification but the oak looks like a sponge with such large pockets.

Thanks Den! Gives me something to cogitate on ;D
I'm a lumberjack and I'm ok, I work all night and sleep all day

Den Socling

Well I don't have time for this stuff  :D but I had to find some American beech this morning. Sure enough, it looks tough.



And I took a look at American Holly which will dry just like potato chips.



Kinda looks like a potato, too.

And finally some easy-to-dry cherry.



There's the piping system, again.

brdmkr

Den

Could you define what you mean by 'easy to dry'?  Do you mean that it is easy to get the water out, or do you mean that the wood dries realively straight with little degrade, etc?

Interesting pics BTW
Lucas 618  Mahindra 4110, FEL and pallet forks, some cant hooks, and a dose of want-to

Don P

I guess I'm dense, what is giving the visual clue as to ease of drying?
The size of vessels doesn't seem to be it, based on your comments. I know those vessels are plugged in the white oak vs "leaky" in red, but if it was the vessel size then cherry would be difficult and eucalyptus easy ???.

Can you put a radial arrow pointing from heart to bark on your slides that I can orient myself on?

I would love to see and hear about the microscope/ photography setup  8).

Den Socling

brdmkr,

I run a vac kiln so, if it is easy to get water out, it is easy to avoid degrade. The reason is that a vacuum kiln can evaporate water that is inside the wood and not just water from the surface. It's the MC gradient which develops between shell and core which causes unequal shrinkage rates that cause degrade in conventional drying.

Don,

All of the pictures to this point have been transverse or of the end grain. The cross section of the stem shows whether the wood is ring porous (red oak) or diffuse porous (E. grandis). The ring porous are easy to crack. After seeing the type and size of the pores, which have lost their end wall to make vessels, I look for tyloses which can block the vessels.

If you turn the wood 'upright' you can see the vessel that is the pore.



My pictures lose a lot but, you may be able to see an open vessel in this red oak.



And I hope you can see the tyloses in the vessels of this white oak.

The next pictures are really hard to display here. Someday I'll make a gallery at our website.

If you turn these samples on edge to look at both the transverse and tangential surfaces, things get real interesting.



In the E. grandis, I now see that those little vessels are all over the place but they are clogged with tyloses.



I had to do the one above - Osage orange.

For the pictures, I just put my digital camera to the eyepiece of my stereo microscope.

Den Socling

Tom worked a couple of my pictures. We'll see how they look.


That's the end view of cherry.


The tyloses in E. grandis


E. grandis edge

Den Socling

Good work Tom. Definitely better than the job I did.

Tom

 ;D ;D smiley_big-grin2

Don P

WOW!  8) 8)

Cool pics!

OK, on Tom's rendition of the tyloses in E grandis. From left to right, look at the second vertical tylose filled vessel. From top to bottom look down the vessel a little less than 1/4 way at the brighter area. Am I seeing the donut shaped pits that connect the vessel to the horizontal ray cells?  And are the horizontal lines I'm seeing medullary rays? That is cool if it is, the vertical and horizontal plumbing.

Where I'm having trouble visualizing orientation, in the ring porous woods the growth rings are obviously along the rows of vessels and the rays are crossing them roughly perpendicular. In the holly I'm not sure where the heart and bark are, I'm assuming the darker bands are latewood and the lighter crossways stripes are the rays?

I could be wrong about all I'm imagining I'm seeing, are you using a steak knife and my rays are just the serrations?  ;D

I had read somewhere that vessels are (born, hatched, er whatever) and then continue to swell in diameter where hardwood cells destined for other functions don't. It mushes the cells around it out of a strict rank and file like softwoods have. The picture of the rays meandering around the vessels on the shagbark is what caught my eye.

That osage would be tough to dry and from the fiber I'm guessing has some tension?

Thanks Den and Tom, I hope you keep posting neat stuff you see, this is cool.

Den Socling

My steak kife is home made. It is in the upper right.


oakiemac

Neat pics Den, thanks for sharing.

Are ring porous woods generally easier to dry? Also I am surprised that you called red oak easy to dry. It seems rather difficult to me, especially in thick lumber like 8/4.
I guess it is actually all relative though.
Mobile Demension sawmill, Bobcat 873 loader, 3 dry kilns and a long "to do" list.

DanG

I have nothing to add but my thanks.  This is an excellent tutorial on wood structure, and has cleared up some questions I didn't know enough to ask.  Y'all keep it coming! 8) 8)
"I don't feel like an old man.  I feel like a young man who has something wrong with him."  Dick Cavett
"Beat not thy sword into a plowshare, rather beat the sword of thine enemy into a plowshare."

Den Socling

oakiemac,

Ring porous can be difficult. Red oak likes to tear at the rays. I wonder if water traveling through the vessels contributes to that? Vacuum drying can use those vessels as pipelines and boil water inside the wood but I still get a board here or there that has surface checks. I recently dried some wide, flat sawn 4/4 red oak that had fallen in a friends back yard. I don't normally use end sealer but I should have on that load. Some ends had some serous checks. But then, he sliced up everything - sawed right through the pith.  :D

jimF

Den,How long was the oak cut before drying?  In a matter of minutes oak can develop surface and end checks if it is warm and breezy

Den Socling

I know how quickly those checks can start. Even if you can't see them they may be started.

My friend brought the first load in the back of a pickup with no cover on a hot day. I gave him my trailer and a tarp for the rest.

A couple weeks ago, a company sent me 12/4 white oak for a test run. I usually spell out end sealer and stretch wrap for such wood coming by truck but I thought these guys would know. You can imagine my shock when a common carrier rolled up the door of his baking hot trailer and there sat the bare WO strapped to a pallet. Never assume anything, right?

jkj

Anyone interested in this topic might want to acquire two books, "Understand Wood" and "Identifying Wood" by R. Bruce Hoadley.  These are the best I've seen to learn about the growth, structure, and properties of wood including much information on shrinkage and drying.  "Understanding Wood" has excellent information valuable to anyone who saws or uses wood.

"Identifying Wood" guides you through the process of identifying wood from a small sample.   Hoadley describes how to properly prepare samples for examination with a hand lens or low power microscope.  It is important to use a razor blade to get to a surface undisturbed by sawing.  He includes many outstanding photos of common domestic and imported tropical wood cross-sections for easy identification of mystery wood.

I use a 15/30 power binocular microscope to examine wood samples, but you can use a 10x hand lens.  Among the interesting woods is Cocobolo, whose pores are plugged, not with tyloses as are the white oaks, black locust, and osage orange, but with a hard amber-like resin.  It is also fascinating to cut a small cube with the sides on the radial, transverse, and tangential axes and prepare clean edges around one corner.  You can then hold the corner under the microscope and turn it to see in stereo how the pores, longitudinal cells and ray cells interleave, to easily visualize the structure of the wood.  It is interesting how some species look like sponges and some like concrete.

My copy of "Identifying Wood" books is so well worn, it is beginning to fall apart!

JKJ
LT-15 for farm and fun

Den Socling

I have Understanding Wood. I wished the microscopic photos were in color. That's why I started the pictures. I'll order Identifying Wood tonight. It sounds even better.

jkj

Quote from: Den Socling on June 23, 2006, 06:01:31 PM
I wished the microscopic photos were in color.

The primary macro reference photos (those at 10x or so) in "Identifying Wood" are all in color.  The high power photomicrographs (250x, etc) showing the cells and intervessel pits are in black and white.

I've read through "Understanding Wood" several times, but I use "Identifying Wood" as a constant reference.

JKJ
LT-15 for farm and fun

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