Shake, ring shake, wind shake in timber

[pine]

I thought I knew and at least partially understood what shake is/was. 

After a conversation yesterday I decided that maybe I had a misunderstanding of the term.  As a result I have spent a fair amount of time this morning looking up examples of, and definitions of, shake, ring shake and wind shake.  Some say that shake is shake and others say that there is a difference between the names.  Some say it is all caused by bacteria and that the wind has nothing to do with what is called wind shake.

I am referring to a fresh cut trees not kiln dried lumber.

It appears that there are some folks, very well educated, that say that shake runs parallel to the growth rings and only parallel, and that the wind shake that many describe that radiates perpendicular to the growth ring is not shake at all. 

Many examples that I found showed wind shake perpendicular to the growth rings as radial cracks extending, in most cases, only partially through the log but in some cases completely from pith to the outer growth ring.  These were from folks that worked in the industry for decades but may not have the technical education that others have.  The pictures all showed cracks that were of a size that they could be seen and had separation of material.

There also appears to be a difference between what people refer to as "shake" between the western US and the central and eastern US regions.

The conversation I had that started this inquiry was when an individual showed me a cookie that he had cut from some red alder (Alnus rubra) that had a very tight grain but multiple visual lines radiating/running from pith to the outer growth ring and even into the bark. Lines were clearly seen but there was no cracking/separation of material (yet) in the wood.  He described it as something that would make it more valuable as a desired "figure" in the grain.

Having always thought of shake as a bad thing I became intrigued and started trying to become more knowledgeable. Now I turn the experts here.
Thanks

[beenthere]

You ciphered out the "wind shake" misnomer very well.
Growth stresses likely cause the radial checks, and not wind.

Good summary of the topic

[mad murdock]

A term with which I am not too familiar I came across out here in the PNW is "spangle".  There seems to be different interpretations for that as well. What does spangle refer to?  My limited research on the term leads me to believe it is associated with heavy pitch pockets? Is it something that occurs mainly in old growth trees?

[beenthere]

When more than two heart checks occur in the end of a log, the defect is called spangle.

Found in USFS pub on cu.ft. log scaling.

But think it is a catch-all when scaling a log and several things, such as pitch and checks, show up on the log end.

[mad murdock]

Thanks Beenthere!!

[GeneWengert-WoodDoc]

Shake, wind shake and ring shake (and also ring failure, ring separation, and ring check) are the same thing...a separation of the wood parallel to the growth rings.  The separation can occur within a growth ring or at the junction between adjacent rings.  In 99.99% of the cases of shake, the basic cause is a weakening of the wood caused by anaerobic bacteria that come into the tree stem through the roots.  These bacteria create an enzyme that dissolves part of the wood structure, making the attachment between the cells much weaker than normal.  So, normal stresses in the life of the tree create the failures called shake.  These bacteria also create very high MCs in the stem while the tree is growing.  They also create basic fatty acids that turn rancid and give the wood a very foul odor.  In dry lumber, these bacteria, although dead in dry lumber, are responsible for wet pockets--small high MC areas in a piece of lumber that is quite dry everywhere except in these few spots.  The bacteria thrive in the soil when the soil is wet and warm.  They enter the roots through injuries, often caused by cattle grazing or a previous logging operation.  Usually, due to the slow spread of the bacteria, trees are 75 years old before the effects are seen in the main stem.

Because of the weakening of the the wood caused by the bacteria, it is common to see splits or checks running across the rings as well in the infected area.  In bacterially weakened wood, end checks and splits and also surface checks and honeycomb are commonly seen.   But radial cracks running across the rings (when viewed from the end grain) should not be called shake.  For hardwoods, the definition of shake is correctly given in the Rules; likewise, when grading softwoods, shake is correctly defined.  In texts that are over 50 years old, the failure parallel to the rings was called ring failure or shake.  The Textbook of Wood Technology also correctly defines shake.  The latest version of the US Forest Products Lab's WOOD HANDBOOK (2010) has shake defined as going parallel to the rings and synonymous with ring failure.  A similar definition is in the DRY KILN OPERATOR'S MANUAL (1956).  In 1926, they called shake "honeycombing along the rings."  The term shake seems to have entered our wood vocabulary in the late 40s or early 50s.

It was only about 35 years ago that the cause of shake (bacterial) was firmly established, with most of the the early work being done with western hemlock by a microbiologist, James Ward.  However, shake and its quality loss was well known at least 100 years ago in both softwoods and hardwoods.  In fact, if you see some old logging pictures, once in a while you will see that they cut high stumps.  Evidence points to the reason for such practice...the loggers knew that the lower portion of the stem had shake and was of poor quality, so a high stump left the defect in the woods and not at the mill.

Some species, such as hemlock (east and west), cottonwood, willow and aspen seem to be quite susceptible to this bacterial infection and shake.

With the high increase in MC when the bacteria are present, it is common to find that the log will not float in water very well.  In fact, many of the logs on the bottom of rivers, lakes and ponds are actually bacterially infected and that is why they sunk.  Although the bacteria are gone, the weak wood effect is still there.  For this reason, sunken wood must be dried much more slowly than "normal" wood.

[mesquite buckeye]

My red oaks get it. Shingle oak usually gets it.

[GeneWengert-WoodDoc]

Here is my GUESS about spangle in logs or wood.  When dealing with amber, the term refers to color variations due to inclusions in the amber (sun spangles, for example).  Amber comes from tree resin.  So, it would make sense (but not every term in our industry does make sense) when we have several or more sap pockets in a tree or lumber, we would call it spangled, especially if it has inclusions in the amber, which is often true.  I wonder where the town of Spangle, WA got its name?

[Peter Drouin]

And when you buy hemlock you better have a good eye for shake. Or you can lose a lot of $ if you miss it and try to make lumber out of it. The lumber will fall apart on you. I have seen times when the logs set for 2 or 3 weeks and it shows up later.

[mad murdock]

Thanks for the expanded definitions wooddoc!!

[beenthere]

And more in reference to pitch from:
http://www.ibsp.idaho.gov/2409.11_30.htm

 

 

And in:
http://www.timbermeasure.com/Bellingham_2013/Carrier.pdf

Spangle is defined as more than two pitch seams

[petefrom bearswamp]

Peter It seems to me that sometimes the shake in Hemlock doesn't show up right away.
I have made my share of kindling wood sawing Hemlock.
My biggest mistake was buying a whack of logs that were snow covered and had lots.
My laziness in not doing a lot of shoveling.
Current inventory of Hemlock logs is nice and large dia  and not much shake.
Doc In the dark ages (1958) we were told that the cause was wind, thanks for the clarification especially about the MC.

[ST Ranch]

Gene - many thanks for your post on this matter - as a scaler, forester, past logger and sawmiller, I had always been of the understanding that shake was from the wind and not from a biotic source. The disease explanation really makes sense.  It clears up the confusion I had about individual trees I cut from the lower portion of the forest canopy that had extreme shake and always found it hard to undertand the "wind " factor.
Learn something new every day.
Tom

[Peter Drouin]

If the ends are white on hemlock, No dark heart is the best , If dark heart and ½ moon black thing on the rings is bad,bad. And that is not a sure thing.

[47sawdust]

I am thinking of buying a load of hemlock that was cut this winter.The logs are on the landing and I will scale them and have them delivered to my mill.
Is there a conclusive way to identify shake in these logs?
Maybe this has been answered already and I haven't found the thread.
Thanks for help,Mick

[beenthere]

Would think shake would be visible on the ends of the logs.

[drobertson]

Me too, seen it on the butt ends, lobbed off sections until it cleared up, sometimes it goes to far up to save the log. Always figured it was disease, which then in compounded by high winds,

[LaneC]

I was wondering if shake is more common in the Northerly cooler climates than in the South where it is usually hotter?

[Ron Wenrich]

I think it depends on your area and the species of trees.  I don't find all that much shake in hemlock in this area.  Its usually something I can saw around.  Pin oak is usually stinky and shakey.  I've also seen it in sycamore.  I've also seen it in black oak, but its usually seen with "mineral".  What's called mineral is usually the bacteria stain.  That grows in some areas, and not in others within the region.  I don't think you can pin it on a temperature thing, if that's what you're driving at.

[GeneWengert-WoodDoc]

Shake results because a bacteria has gotten into the tree through the roots.  These bacteria create an enzyme that weakens the connection between the growth rings.  It is an anaerobic bacteria, so it like "no air" conditions.  That is why the moisture content is also high around shake.

So, shake is more common where the growth of the bacteria is favored--in wet sites (many are in the South), in warm sites where the bacteria can grow rapidly, and in sites that have had previous logging or other soil disturbance which injures the roots providing an entry way for the bacteria.  For some reason, perhaps related to pH, some species seem more prone to infection.  Those more prone seem to be western hemlock, eastern hemlock, aspen, cottonwood, elm and some oaks with wide ring spacing.  But we believe that shake exists in all species.

Because they enter through the roots and then moves an inch or two a year, the bacteria will be found in the butt log and usually just the lower portion of the butt log.  That is also, when the bacterial infection is severe, where we see shake.  So, looking at the end grain on the lower end of the butt log will tell you if shake is present, but not how far up the stem it goes.  I was involved with a Wisconsin mill that started sawing eastern hemlock that was about 125 years old.  After a half-day of sawing, they quit due to the high amount of defect.  In drying, even more defect showed up.  After some study, it seemed that logs under 75 years old still had sawlog potential, but older logs were pulpwood.