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Home » Installation » Wind shake - hear it when sanding?

Unfinished, prefinished, subfloor prep, etc.
3/29/2012 10:04:32 AM

Kim Wahlgren
Kim Wahlgren
Administrator
Posts: 110
Someone submitted this question to our website:

Wind shake is a new experience for us. We installed about 2500 SF of # 2 , 3-1/3 white oak. We applied stain from Minwax, a sealer and three coats of Bona Mega. One or two days after we finished the floor started to erupt and splinter. The Bona rep. indicated that moisture crept into in the "wind shake" (hollow) spots and caused the boards to splinter. We ended up replacing over 100 boards and completely refinished a majority of the project. A NOFMA certified inspector indicated that we were supposed to hear the “wind shake" (hollow) spots during the sanding process. Are we being fed some bull or is he correct?
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3/29/2012 11:33:21 AM

Dan Schultz
Dan Schultz
Posts: 68
I have never heard shake wile sanding a floor. It's possible that's because I've never sanded a floor with boards containing shake.

Over 100 boards in a 2,500 sf floor sounds like quite a few more than I would expect to find, but not that I haven't. A #2 common floor is likely to contain more mineral streaks than the higher grades. Mineral streaks that follow the annual growth rings are a common place to find shake.

For other ways to help locate shake in boards see an article in the June/July 2010 issue of Hardwood Floors Magazine.

http://hardwoodfloorsmag.com/articles/article.aspx?articleid=1208&zoneid=2
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3/29/2012 2:46:13 PM

TDMAC
TDMAC
Posts: 1196
Hearing the hollow sound of wind-shake while running a sander would be difficult. We don't drag a stethoscope around: During the screening process, I would think that hollow sound might be heard.
Dan's tapping etc in his article sounds interesting though I usually see wind-shake in finger block.. Rarely in #1 or #2, but I don't do a lot of #2. I am curious about the trees that produce more wind-shake. Are they from areas with Hurricanes? Maybe Dan knows this answer.
Also is wind-shake more prevalent with Quartered 'flakes " I see on quartered finger block pieces?

I have never smelled any poop smelly wood in a long time, so that wood be stinky!! smile
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3/29/2012 2:55:06 PM

Plepine
Plepine
Posts: 123
What is wind shake exactly? i cant imagine what it is :S
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3/29/2012 3:43:30 PM

kevind
kevind
Posts: 39
It's normally where the tree has been stressed by wind to the point where the piece separates along the growth rings. also know as ring shake,ring failure,shell shake.
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3/29/2012 6:12:33 PM

Jeff
Jeff
Posts: 258
I usually get a few boards with #2 but a hundred seems a bit much. I try to buff without hearing protection so I can "hear" the shake...it makes a "ssss" sound. When I hear them I find out big it is...if its small I cut out the bad spot with a utility knife and fill it, of it's big the board has to come out.
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3/29/2012 6:45:11 PM

johannes
johannes
Posts: 394
I have been told by a mill guy in Northern MI that he could smell windshake. Thought he was pulling my leg until I learned that what we call “wind-shake” is actually caused by bacterial causes. It has typically nothing to do with wind. The bacteria are part of the “clostridium genus” and often in the mill it may be noticed by the bad odor it emits when the wood is sawn. The bacteria will have weakened the wood in the area it is present and will extend beyond the actual separation between the grow rings. Often that area will also exhibit a higher MC while unaffected areas are reading a lower MC. Scientist believe that affected wood may have grown in a very wet (swampy) area.
This higher MC in the affected areas may also be helpful in detecting a potential problem when milling the wood after it has been kiln dried. But you need a skilled operator who keys into that. Not every individual has that skill. Besides that in the mill the light source has to be good to visually help detect windshake and cull it during milling. Windshake is often difficult to visually detect.
So, it is easy to understand that some affected boards may get unnoticed and make it out to jobsites.
Windshake occurs parallel to the grow rings, you can typically hear it by tapping on the wood if you suspect it and also during sanding it may become noticeable. Separation may not be present extensively (which then you may not hear the “hollow sound” when being tapped on) but may worsen when excessive amounts of moisture get introduced to wood by means of applying a waterborne finish. When the moisture from the finish evaporates it may cause enough stress that the windshake actually “springs” further loose and stick up above the wood substrate. Very often screens/conditioning pads will catch on such areas or you may notice “burning thru” little spots that stick up (particularly when stained) along edges of boards.
I do not know what tolerances are actually allowed by the mill and/or NWFA/NOFMA but I would at least discuss it with somebody of authority at the distributor or the mill.
To say you should have noticed it during sanding may be partially correct but is not fair as it may later occur with finishing with an H20 product. I think that 100 boards is also quite a few too many to my liking/acceptance.

Johannes
edited by johannes on 3/29/2012
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3/29/2012 7:46:36 PM

Avi Hadad
Avi Hadad
Posts: 232
My entire reply assumes you know what you are doing;
To answer your questions: Yes, you are being fed and you can quote me on this.
And, if you have about a hundred boards which you had to replace, a hundred boards you did not notice had shake while sanding and coating then something else might be going on. Water base will reveal the shake after one coat so maybe you should call a good NWFACP inspector since NOFMA does not exist anymore.

Avi's Hardwood Floors
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3/30/2012 12:34:49 AM

Roy Reichow
Roy Reichow
Moderator
Posts: 342
Wind shake is not part of the grade but also the hardest to prove. If msnufacture or installer can't see it then it would be classified as a latent defect meaning no blame. If you work with lower grades then you
should bid higher labor costs for that reason. I have found #2
common white oak and birch has
more. One way to check for
shake before final sanding is mist the floor using an garden sprayer. One will see the shake, complete board replacement before drum is hauled. If you have more than 6 boards per 1,000 SF, find yourself a better mill.

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Roy Reichow
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3/30/2012 11:00:50 AM

TDMAC
TDMAC
Posts: 1196
Roy, so simple and logical. Water misting pops the grain
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3/30/2012 12:03:07 PM

kevind
kevind
Posts: 39
Id say finding a new supplier is the best advice, especially if they are saying that amount is normal in #2 common
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3/30/2012 7:08:24 PM

Stephen Perrera
Stephen Perrera
Posts: 955
You'd a thunk a guy could hear it when throwin down the wood to rack it out. Should sound like a broken bat.
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3/30/2012 9:12:18 PM

hbrickman
hbrickman
Posts: 136
grooving wrote:
You'd a thunk a guy could hear it when throwin down the wood to rack it out. Should sound like a broken bat.


It is my experience that the individual shakey boards actually rattle. Perhaps if the installers would take out the ear plugs for the iPod they might be able to hear it. There is also a very distinctive pfffffft sound when you are sccreening

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Brickman Consulting
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3/30/2012 9:27:54 PM

TDMAC
TDMAC
Posts: 1196
PFFFFTTTT? Howard? That happened when My Sander hit a Cat!!!
OK just in Jest, I thought it made a sound like SPPPPTTFF, but I am loosing my hearing. Naw, you know the IPOD will win!!
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3/31/2012 6:20:00 AM

Roy Reichow
Roy Reichow
Moderator
Posts: 342
TDMAC

It is simple and it works. One thing we must keep in mind lower grades take more time to lay,sand and finish than a clear grade. For client satisfaction one must figure board replacement for these grades. That's why taking a few minutes to water pop before final sanding will guarantee the outcome. Where the thread we read he has to redo the work for free. We charge more per SF for lower grades due to the extra time.

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Roy Reichow
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3/31/2012 4:25:57 PM

TDMAC
TDMAC
Posts: 1196
ROY That is total common sense and $$ also. Great to know that trick. I rarely do any #2common, but I will program that into my head if i do.
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3/31/2012 7:13:23 PM

Roy Reichow
Roy Reichow
Moderator
Posts: 342
TDMAC remember the fire I spoke of on another thread due to spontaneous combustion. Well windshake was the cause of the board replacement and resand. Thats why we use the water pop presand system in our policy for stain or waterbase jobs. We also use light water pop on resand of prefinished. After 5 minutes one can clearly see any waterbase finish residue before applying new finish or stain.

Roy Reichow

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Roy Reichow
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3/31/2012 8:13:43 PM

Plepine
Plepine
Posts: 123
on a stain job i did last week i notice one while i was staining ... was too late to fixe it :S
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3/31/2012 8:25:37 PM

Roy Reichow
Roy Reichow
Moderator
Posts: 342
Plepine one trick we use is CA glue (superglue) to fix small ones on the fly, it's part of our tool kit

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Roy Reichow
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3/31/2012 8:28:21 PM

TDMAC
TDMAC
Posts: 1196
Roy, OK be more specific on that . email me direct!
Thx
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