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Preventing checks in timbers

Started by Thehardway, December 31, 2007, 11:00:46 PM

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Thehardway

I know this is impossible and to some even undesirable.  I know there is no silver bullet but here is the question.

Just about everything I read says paint the ends of timbers to prevent splitting.   I also read that the majority of drying takes place out of the ends and sealing the ends slows the dring process.  then I read that the primary cause of checking is the surface drying faster than the inner core.
That seems to make everything all backwards. Wouldn't one would be better able to prevent checking by sealing the surface faces and leave the ends un-sealed to dissapate moisture from the core faster or equal to the drying rate of the surfaces and thereby minimizing the checks?

I have also read however that sealing the surfaces prior to seasoning and drying may cause the checking to be worsened later on or even cause rot.  Despite this most TF companies state that timbers are delivered to sight planed, chamfered and oiled.

Where is the common sense in all of this?  I have seen timbers with ends split after sealing and ones that don't without sealing.  I cut two Black Cherry timbers and coated both with boiled linseed on ends and all four surfaces.  One checked severely in about 2 weeks and one is still perfect 3 months later. 

I am currently cutting joinery on 7X10 White Oak timbers that are fairly green and wet.  When I surface plane them you can see that they have dried about 1/8 inch deep on the surface.  When making end cuts the wood is still wet 1/16th from the end. After two weeks there are no new visible signs of ends splitting or checking on the suface.  I have kept them stacked/stickered under roof but open to air circulation and out of direct sunlight.  It has been extremely damp and the temps have been mid 30's at night to mid 50's in the day.  (Slow drying weather)

I am planning to coat all joinery on ends as I cut it with linseed oil. I will repeat this 2 or three times a day or so apart until it no longer is absorbed.  Will then coat with Beeswax.  Is this a good plan?  I anticipate that the drying process in these timbers will probably take 5-10 years and I expect some checking to occur over time.  I just don't understand the logic of what I have read.

Frame joinery will be test fitted in a week or two at which time I plan to sand and suface coat with a light rubbing of 50/50 Linseed and Tung oil to prevent staining until final assembly around the end of Jan, or sometime in Feb.

What methods do you use or not use and what has yielded favorable results when working with some harder/slower to dry species like White Oak?
Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

WDH

I am no timber framer, let me say right off. 

The end of the cant checks because the end grain shows the open end of the wood pores (the pores are cut open in cross-section, like cutting the end off a bundle of straws), allowing water to evaporate rapidly since all the pores are open to evaporation. 

Now if you imagine the long sides of the cant, think about the same bundle of straws laid flat lengthwise.  Now slice through them lengthwise.  A few straws will be sliced open , but all the straws below and above the cut will be whole, so evaporation is very very much slower (except on the ends where they are open.

I have had very good results coating the ends of logs/cants with aluminum roofing paint (Cool-Seal at Lowes), but the aluminum paint is terrible to clean up.  I have also have very good luck with anchorseal that you can order from Baileys's, one of our sponsors.  It cleans up with water and is wonderful stuff.  Anchorseal would be a whole lot easier to apply than  Linseed Oil, and you have to only do it once. 
Woodmizer LT40HDD35, John Deere 2155, Kubota M5-111, Kubota L2501, Nyle L53 Dehumidification Kiln, and a passion for all things with leafs, twigs, and bark.  hamsleyhardwood.com

Furby

I don't believe oil is considered a sealer, I believe it breaths.

logwalker

I sealed up mine with Cetol SRD early in the process and it seemed to work well. But it is like asking whether concrete is going to crack. It is not a matter of if but of when. Comes with the territory, good luck in the new year. Joe
Let's all be careful out there tomorrow. Lt40hd, 22' Kenworth Flatbed rollback dump, MM45B Mitsubishi trackhoe, Clark5000lb Forklift, Kubota L2850 tractor

ljmathias

Interesting comment about concrete cracking- and not to hijack this thread- but there are cracks and then there are CRACKS.  My last three slab pours I overkilled big time: rebar in the footings and stretched across the slab and tied into the footings with remesh on top and tied to the rebar and then concrete with 'fiber' in it.  My theory is that the fiber stops or slows down the tiny cracks which want to become the big cracks which are held in check by the remesh and rebar.  Seems to be working so far- either no cracks or just tiny ones that don't seem to be all that damaging.

So what if we could do the same with wood?  Use a sealer that prevented end loss of moisture but also helped hold the ends together while the wood dried and stabilized?  Probably way too expensive to try but I'm thinking a thin coat of epoxy or urethane?  This would only be on unexposed parts or ones to be cut off later....

Probably a really bad idea but couldn't sleep out the night- too much to do today and not enough time and energy this time of year (how do they survive in Alaska with 4 hours of daylight or less in the winter?)

Lj
LT40, Long tractor with FEL and backhoe, lots of TF tools, beautiful wife of 50 years plus 4 kids, 5 grandsons AND TWO GRANDDAUGHTERS all healthy plus too many ideas and plans and not enough time and energy

Thehardway

Lj,

I have thought about the exact same thing you mention.  What if we put fiberglass matte over the end and did a wet down with resin? 

WDH, 

I understand the bundle of straws concept and how the wood fibers are arranged.  This applies to most open grain woods. However, true White Oak  I have been told is one wood that this does not apply to as it is has blocking tyloses which in essence plug the straws. This is the very thing that allows it to have such superior weather and anti-rot properties.   It also maked it slow and difficult to dry.

Let's carry this theory to other woods that follow the straw example.  If the log was perfectly straight and had no knots, branches or grain variation, then only a few straws would be split lengthwise and the theory would be true.  Most logs do not fit this profile.  The grain may leave the edge of the log several times along the length of a timber or cant, therefore if all drying out the end of the straws is to be stopped the surfaces of the cant must be sealed as well or at least any place where the grain leaves the edge of the timber.  Does this make sense?  Also considering the relative percentage of surface area of a sawn member in relationship to area of its end grain it would seem that evaporation through the surface would be at least equivalent.

Experiment: Take an 8'  8/4 sawn board that contains either all sapwood or all heartwood so that it is homogenus in density and moisture content.  Air dry it for a month without sealing any surfaces. Then saw 6" off of each end. Check moiture content at center and work towards the edges.  Is moisture content greater in the middle or at the edges?

Furby,

Linseed oil forms an air/ wator proof barrier although this effect is lessened as it is soaked up by the wood therefore multiple coats are neccessary to completely "waterproof" wood. It does this by basically the same means as the tyloses in White Oak.  It plugs the straws.  As an interesting note linseed was used to make canvas cloths waterproof for tents and also to make wooden fishing items float by preventing them from soaking up water.  Tung oil is similar.  Other oils may not so I cannot speak for them

My theory right now is that it may be best only to Slow the drying process and try to equalize it rather than completely Stop it by sealing with stuff like anchorseal which could cause other problems.  What do you think?   

Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

Ironwood

FYI,

Early in this century (1900's) they center bored timbers to prevent checking. Don't ask me how they did it, but I have literally tons of these timbers from a brick yard in Washington Pa. that was next to Allegheny Ludlum Steel. I will be selling them soon.

          Reid
There is no scarcity of opportunity to make a living at what you love to do, there is only scarcity of resolve to make it happen.- Wayne Dyer

logwalker

I had that thought about centerboring. I'll bet it works well. How large of a hole did they bore, Reid?
Let's all be careful out there tomorrow. Lt40hd, 22' Kenworth Flatbed rollback dump, MM45B Mitsubishi trackhoe, Clark5000lb Forklift, Kubota L2850 tractor

logman

Use Anchorseal, it definitely works.  I end coat all my logs as soon as I get them.  I had some (oak) sit for quite a few months before I sawed them and had little checking.  I also end coat my timbers after I cut the joinery to help prevent checking. 
LT40HD, 12' ext, 5105 JD tractor, Genie GTH5519 telehandler
M&K Timber Works

JGroebner

Checking = Character   It is the natural process, however, I have seen several frames with zero checks, from what I can tell they applied and re-applied many many layers of oil. 

I'm SO happy we ONLY use salvaged timber frames and our customers appreciate ZERO shrinkage and BEAUTIFUL checks.  After all it's still a timber frame and it's still stronger than a stick frame with many more benefits.

Jared

Thehardway

Centerboring sounds like a great idea to equalize the drying speed.  I also am curious to know more about this teqhnique.  Species and size of hole would be great a picture even better.  I wonder how these would effect the strength properties.  I would assume it is in the neutral plane so it would be negligable?  Might be usable as a chase for wiring?
Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

Ironwood

I will get a good picture tomorrow. Most of my pics are of the overall pile (about 20-25 tons worth of timbers) I had planned on selliing the "lot" to a flooring manufacturer, but doen't matter to me, most are 12-14' and 10x10's thru 13x13's, with about 24 pcs of 6x12 fir floor joists. The 10x10 are the bored ones, looks to be about 1.5" Found some workable pics on file, here you go. Thing that is nice about recycled factory timbers of this vintage is, no mortise pockets and high quality wood. I will be sorting and invertorying these things soon, I will most likely bundle and stick them on pallets. I also have literally thousands of board feet of recycled Hem/ Fir early framing material that I will be getting rid of, all full dimension and denailed up to 3x12 x 30'er's, for the turn of the century buildings, mostly from a local grade school circa 1910. I was going to use it for a new shop but my plans are evolving.









                Ironwood
There is no scarcity of opportunity to make a living at what you love to do, there is only scarcity of resolve to make it happen.- Wayne Dyer

Don P

I'm stepping in late,
but that's never kept me quiet ::) ;D

The only time I've heard the term "Dry Rot" used where it made any kind of sense to me, was in an old text where they talked about not painting timbers till they had seasoned or they would dry rot. I've seen film forming finishes check, admit water, and turn wood to mush inside of that compost bag in a very few years. I think the principle is the same. Totally trapping moisture at high mc's isn't a good idea. You usually can't totally trap moisture, its varying degrees of permeability depending on finish type, coating thickness, etc. Five coats of a breatheable finish is probably about the same as one coat of poly if you follow my train of thought.

Checking is caused by a couple of actions. Internal drying stresses from the way trees shrink, you can do a very little for. Removing the core helps with that, as would a stress relieving groove, so does FOHC timber. The other thing that causes checking is moisture gradient during drying. When the shell is below fiber saturation point it is shrinking. While the core is above FSP it is not. If your jacket shrinks and you don't go on a diet, its going to pop some buttons. I think all forms of prefinishing moderate the rapid shrinking of the shell keeping that zone narrower in dimension and in moisture gradient. If you're too good at slowing moisture loss, it'll rot. If you're not good enough a moderating drying, it'll check more than it should have. I've had good luck with anything that slowed surface moisture loss. On the jobsite drying conditions aren't pretty to begin with, its all over the road. Repeated cycles of the shell rapidly shrinking and swelling drive surface checks deeper. Anything you can do to moderate those swings is going to help.

With bored timbers I'd check horizontal shear carefully,I think it'll be of greatest concern. It is greatest in the neutral plane, concentrating towards the ends. But then a check is often a horizontal shear plane, usually worse near the end. Adjusting the section in the other calcs for the hole would be the way to check bending and deflection. I think it would be a great idea, just allow for it in your calcs.

Anectdotally, and I do believe it, shell guard, PEG carried borate, supposedly also reduces checking. The PEG bulks the shell while the core dries. Peg has finishing problems. In my mind I think I've seen antifreeze, ethylene glycol, help with checking, I'm guessing the  moisture evaporates but the glycol keeps the shell moist. Again lowering the gradient.


Polly

   8)  we been hauling logs to a local yard and they drive a plastic s  shaped piece in the ends of logs to prevent checking  :-\ 8)

Ironwood

Don P.

The term moisture exclusivity comes to mind. This is the term used by the finish trade/ tech guys (that do the science) for the degree of permiability of a given finish. The PEG sure is interesting, greasy when done and finishing issue for sure, read once where "moisture cured varnish" was the final finish of choice (never was able to locate any). I sure would not want that on my logs.

Polly,

I have played a bit w/ those plastic little jobbies (technical term)  ;D, and I was not really impressed. They are also using bar coded plastic jobbies for individaul log id and tracking. All of these do not stain and can be sawn right thru.


Ironwood
There is no scarcity of opportunity to make a living at what you love to do, there is only scarcity of resolve to make it happen.- Wayne Dyer

Dana

I think TW mentioned in a post how in Europe they used to girdle a live tree and let them stand for several years before felling to prevent checking.
Grass-fed beef farmer, part time sawyer

Larry

Reid, since ya brought it up thought I could add a little to the center bored timber story.  One of our resident lurkers and ace TK sawyers, Ron Collins got a job sawing timbers out of an old warehouse in Kansas City.  I visited him on the job and we speculated that most of the timbers were either chestnut or douglas fir.  All were center bored with a hole.

I've always wondered how the holes were drilled.  Most holes went in on center and came out on center.  The timbers showed little sign of checking.  From memory the holes were in the range of 1 1/2 to 2 inches in diameter.  This was really one time I wished that I had the camera and had taken the time to do a little more investigation.

Sure would like to see a picture of a drill and bit that could go through a 12' long timber.
Larry, making useful and beautiful things out of the most environmental friendly material on the planet.

We need to insure our customers understand the importance of our craft.

pineywoods

Quote from: Larry on January 05, 2008, 07:17:32 PM


Sure would like to see a picture of a drill and bit that could go through a 12' long timber.


I have a 2 inch T-handled auger that is six feet long. Never knew what it was used for, found it in the barn when we moved here. Wife's grandad who lived here most of his life, was a traveling peddler. Did a lot of bartering. Local elderly neighbor  told me it was a "stump-getter" used to drill a hole under a stump, then insert a stick of dynamite. I wondered about that, except for the length it looks just like a conventional wood-boring bit.
1995 Wood Mizer LT 40, Liquid cooled kawasaki,homebuilt hydraulics. Homebuilt solar dry kiln.  Woodmaster 718 planner, Kubota M4700 with homemade forks and winch, stihl  028, 029, Ms390
100k bd ft club.Charter member of The Grumpy old Men

Ironwood

Dana,

Those to are 12 x 12's w/ the hole in them. I am no pine expert so I do not know the species. Ironwood
There is no scarcity of opportunity to make a living at what you love to do, there is only scarcity of resolve to make it happen.- Wayne Dyer

Don P

I've seen a drawing of the auger but can't place where, it was in relation to boring wooden water pipe. There were many miles of that stuff made in the old days. The long auger shaft was mounted on a carriage with pillow blocks to align it and for small diameter holes could be turned by hand. The carriage was advanced by a helper. I think the front block slid back as the auger went in to keep it at the front of the log... its been some years  :-\

A little googling brought this up but no pics, sounds like pineywoods' auger;
QuoteThe borers themselves were colorful characters who usually traveled in pairs from town to town bringing news and gossip of the area as they went about their job. With a five-foot steel auger between them, a handle at one end, they would fix the log by eye, size it up with a point of the ax, and drill or bore out the center. Ramming one end to make a conical shape, they would jam the logs together in a series, using a bituminous-like pitch or tar to caulk the joists. Sometimes they would split the log and hollow it out, put it together, connect the logs with iron hoops, or get the blacksmith to caulk the logs with lead.

There was a log home company in the early 90's that was producing a center bored log that was supposed to check less, never saw one in person though.
Found' em;
http://www.airlockloghomes.com/history.shtml
http://www.airlockloghomes.com/thelogs.shtml

scgargoyle

Sounds almost like a gun drill, which is used for drilling very long holes in metal. What surprises me, though, is that it wouldn't wander as it hit variations in the log. I've seen very long augers used to drill the shaft holes in boat keels- don't know how they kept them straight, either. I had a problem once with a customer who was drilling 1/8" diameter holes through solid body electric guitars. The figured maple would make that small bit wander. I made him some half-round bits out of drill blanks, and they went through dead straight every time. But I digress (as usual). Question- would an inspector buy off on timbers with holes drilled through them?
I hope my ship comes in before the dock rots!

Don P

If you can show that they "check out" to his satisfaction. An I beam or an I joist has a large amount of material missing in the zone of the neutral axis. The "extreme fiber" the plane of the outer edges of a beam carry the greatest bending strain. The stuff in the middle is mostly there to keep the 2 faces apart. It must keep the 2 faces rigidly connected to each other to resist them sliding past each other or they would act like 2 shallower beams, that's where my horizontal shear comment came from. Usually... most of the time... but not always... the shear numbers are fairly low, often a 1/2" piece of osb could satisfy the shear requirement, a wood I joist.

JGroebner

I guess I was a little "pre-mature" in stating checks are beautiful.....(I still think they are) I understand to each his own.  After doing a little research I found a product you can buy through www.loghelp.com  it's called Pentacryl.  It's a new product so I'd ask a few people before pulling the trigger.

Jared

Thehardway

 

WOW This thread is getting very educational and exteremly insightful.  This whole centerbore thing has got the old mind gears turning.  When I visited Old Salem, NC they had some relics on display that were supposedly used to bore out logs to make water pipes for the town.  They were basically a type of spoon bit.  I believe these singe sided types of bits could almost be steered.

In modern day underground directional boring, an angled head is placed on the bit. By rotating and ramming the bit can be steered in just about any direction. The location of the bit is determined by following it with a radio transmitter and reciever.   You can even turn corners.  It stands to reason that similar technique would work in wood.

I am just speculating but perhaps this is way early center boring was done.  The bore could be checked for trueness by inserting a straight dowel rod and seeing if it ran through free or tried to bind up.  If it started to bind you worked the bit around the other way until it freed up.

Jared,

I won't dispute the beauty of checks, they certainly do add charachter, I will check out the Pentacryl although things with "penta" in the name make me wonder what kind of malformaties my grandchildren may be afflicted with :D

Norwood LM2000 24HP w/28' bed, Hudson Oscar 18" 32' bed, Woodmaster 718 planer,  Kubota L185D, Stihl 029, Husqvarna 550XP

ARKANSAWYER


   Some wood will check no matter what you do.  You can plunge cut timbers on the back side to make the check where it will not be seen.
  Sealing a timber before it dries will cause it to rot.  White oak will rot if sealed before it dries.  The pores only seal up after the cells have dried.  How else does a live tree live if it is all stopped up?  Water will flow out of a white oak tree.  Or you could never dry the wood down.
  Dry rot is a real danger.  Free of heart timbers do not check as much because the grain is not in a circle around the heart.  The out side shrinks so much as does the inside but the differance is what chauses the check.  Wood like Butternut does not hardly check at all.
  A spoon bit was used to bore up the middle of logs and timbers.  You bore from both ends so a 12 ft long timber only needs a bit 6.5 ft long.  The bit will follow the heart as it is the easist path through the timber or log.  Log water pipes were quite common around springs here.
  Slow steady drying is the best way.  Alot of these timbers that you see out of old buildings were put in pretty green and being inside dried slowly.  They also were of old growth tight ringed trees that also check less.
ARKANSAWYER

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