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Still thinking about how to preserve natural posts  RSS feed

 
pollinator
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Location: Boston, Massachusetts
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Jp Wagner wrote:
I've got the boric acid and the slaked lime. I'll make up a few test pieces and see how the wood reacts. I'll have to figure out if I actually have formed Colemanite inside of the wood somehow. Maybe a microscope and diffraction patterns? It's been way to long since I had a class in geology.  


Is the wood necessary for a test? Meaning, if you combine the two ingredients in a jar, do you get actually even get Colemanite? How quickly does that occur?

How much longer would it take for this to happen in wood when you have separated the two components and they have to "meet in the middle" to react?
Assuming that's what happens, does that "middle area" where the reaction happens retard/stop further migration in either direction? making complete "colemanitization" of the log slower/difficult/impossible? I'm reminded of a concrete waterproofer called Xypex, which forms crystals in the voids of a concrete matrix, sealing it up.

Would a treatment be "quick" as in days or weeks, or longer, like a year or more for a large log? However long it takes, the log will need to be wet... is this a race between rot and preservation?

You say a 36" deep bore in the log, is this just considering the fully buried portion to be at risk? What about the earth-facing side of the wall?
 
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Is the wood necessary for a test? Meaning, if you combine the two ingredients in a jar, do you get actually even get Colemanite? How quickly does that occur?

How much longer would it take for this to happen in wood when you have separated the two components and they have to "meet in the middle" to react?
Assuming that's what happens, does that "middle area" where the reaction happens retard/stop further migration in either direction? making complete "colemanitization" of the log slower/difficult/impossible? I'm reminded of a concrete waterproofer called Xypex, which forms crystals in the voids of a concrete matrix, sealing it up.

Would a treatment be "quick" as in days or weeks, or longer, like a year or more for a large log? However long it takes, the log will need to be wet... is this a race between rot and preservation?

You say a 36" deep bore in the log, is this just considering the fully buried portion to be at risk? What about the earth-facing side of the wall?



The reaction between boric acid and calcium hydroxide is very quick. The Colemanite will precipitate out as a solid almost immediately. As far as everything else...who knows? My intuition tells me the Colemanite wouldn't be a continual solid but more like a matrix with a lot of holes. The holes should allow passage of water which will contain calcium hydroxide. As far as rate of reaction, it would depend on the species of wood and its initial water content. Diffusion outwards would probably be more rapid since the polypropylene glycol would seek out moisture in the wood and aid in the diffusion. The surface of the log would have to be surface treated with borates to stop the preservation/rot battle. For total reaction I would guess at least a year, depending on wood type, initial moisture content, and external moisture intrusion. There are a lot of guesses in all of this.

Another idea would be to add some boric acid to the lime concrete mix. That way you would have a constant supply of slowly dissolving Colemanite to eliminate any chance of rot until the process of "Colemanization" is complete. If enough boric acid was added to the lime concrete you would essentially have Colemanite concrete. You could make the binding agent in the concrete Portland cement and use the slaked lime and boric acid as additives. 20 pounds or so of Colemanite in a 400 pound concrete mix would make that pole pretty much last forever. You could add an excess of slaked lime so the diffusion reaction and "Colemanization" of the post could continue. I'm pretty sure the American Borate Company sells Colemanite directly for use as a fertilizer. Heck, just mix it in directly with the concrete and maybe be done with it. Maybe you could even get a nice deep bucket and put it in the excavation and backfill it with gravel or sand leaving the bucket empty. Then put in the post and Colemanite concrete. At that point who cares if it gets wet and soaks the post. The Colemanite will leach into the post and by capillary action protect the post for probably a foot or so out of the ground. There are a lot of things to try.

 
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Hello Jp,

Love your idea about preserving wood below soil level. Appreciate your wanting to test it before you execute your building plan. I don't have degrees in chemistry. Would it be possible to soak wood posts in boric acid/polypropylene glycol solution until saturated, then in the lime to mineralize it, then use it in the soil?

Doing it this way, wouldn't it be easier to test it in a few weeks time under extreme conditions?
 
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"Hi John,

You are mostly correct about the fence posts and rot but not for the reason you think. The posts are fine underground since they are not exposed to a large amount of oxygen. They will eventually rot as there are anaerobic decomposers but they are not nearly as efficient as aerobic ones. The post from 6" underground to the bottom of the post can have a lot of moisture and that's not really a problem. What you can't have is moisture and oxygen together. ..."

I think you made my point without realizing it. If you had two variables to control, oxygen or water, which is easier to accomplish? Water denial would be the obvious choice.

Do posts fail as I have described? Sure do, after about 20yrs or so which is acceptable pattern for me. For a housing structure probably not however which is generally why other techniques are used for ground contact -- the most common being 'Don't even try'. In my area there are several historical settlers homes that still exist. All of them are using either a stone foundation or brick as pads for joist and frame construction.

 
Jp Wagner
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john mcginnis wrote:

"Hi John,

You are mostly correct about the fence posts and rot but not for the reason you think. The posts are fine underground since they are not exposed to a large amount of oxygen. They will eventually rot as there are anaerobic decomposers but they are not nearly as efficient as aerobic ones. The post from 6" underground to the bottom of the post can have a lot of moisture and that's not really a problem. What you can't have is moisture and oxygen together. ..."

I think you made my point without realizing it. If you had two variables to control, oxygen or water, which is easier to accomplish? Water denial would be the obvious choice.

Do posts fail as I have described? Sure do, after about 20yrs or so which is acceptable pattern for me. For a housing structure probably not however which is generally why other techniques are used for ground contact -- the most common being 'Don't even try'. In my area there are several historical settlers homes that still exist. All of them are using either a stone foundation or brick as pads for joist and frame construction.



Water control depends on your location more than design. It's real easy in Arizona and almost impossible in Oregon. Eventually things are going to get wet. The only thing we can control completely is the food aspect. We have to remove the food source from the equation then we don't have to spin our wheels trying to control moisture. Granted, it can be done but I've never seen it done successfully with untreated wood in ground contact.

To your point, plinth blocks and other methods to get the wood out of harms way is the way to go. I'm trying to figure out the simplest, cheapest, and longest lasting way to get'r done. I'm leaning towards concrete piers with stainless steel rebar welded to brackets to hold the timbers above ground. On the inside of the brackets I'll weld some truss nail plates then bolt everything together. The truss plates will transfer lateral load to the metal plates, rebar, and the concrete piers. I need to use about 30 12X12X12 timbers. These are about $30 a linear foot if I buy them. They are almost free with a chainsaw and a buck in gas. I can't afford 10K+ just for the timber supports. I'll try the treatment I mentioned to start this post (pun intended) for the internal non-load bearing walls. That way if I need to go back and switch something out it won't be a structural issue. I'll still bore holes in the 12X12's and fill them up with borate though. That way I'm protected at least up to 4'.
 
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Jp Wagner wrote: It's not the wet that hurts the wood but the wet/dry cycling. Only at certain points on the moisture content curve can things grow. Too much or too little moisture kills them or makes them go dormant.



That is a fact. The posts that are supporting a 120 year old church in Boston's Back Bay (drained marshland) have no rot, they are kept wet-- submerged. That isn't a solution for set-and-forget fence posts.

As more than one reply has said, using wood that doesn't rot: black locust and osage orange, is the simplest answer. They will last 50 years or more, and no extra work/treatments needed. With the usual rate of uptake for a new idea, there is plenty of time to grow more, enough to supply all the building supply stores in the country. Black locust grow quickly, osage orange probably does also. They biggest challenge is getting them off the list of banned weed trees.

I love the living fenceposts idea. They won't give too much shade, they will help you grow things that need shade, or they will give you a second crop. Yes, those living fence posts. Bees love locust blossoms, so rather than a problem you have a sweet solution. Keep it simple and you can skip most technological or chemical fixes.
 
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I've got an ongoing experiment with muh fence posts...due to a previous experiment a few years back.

I had a few gallons of copper acetate sitting on a shelf, which was made with equal parts hydrogen peroxide and distilled vinegar, + a small piece of copper.  All you do is combine the liquids, then let the copper sit in the liquid and bubble slowly until the liquid takes on a vibrant blue color a few days later (or sooner based on surface area of copper scrap used)

So copper.  It's not cheap, but it only takes small amount (like a nail or 2?) to make a gallon of this stuff.  My reading had only said something like "warning, dissolved copper is toxic.  Wear gloves and and don't get it on your skin."   Apparently this dissolved copper is a somewhat powerful poison, fucking up any biological system it encounters.  Like a dozen drops from a dropper on a hypochaeris root in high and dry summer caused it to shrivel up and die in a few days.  Because of this clearly observed toxicity, I figured I better not dump my few gallons of leftover chemicals on the edge of the property (because it's just vinegar, peroxide and a small piece of copper, like how bad can it be? - haha) So I held on to the pretty blue poison, just until I could make a run to hazardous waste disposal at the dump, to pay money to dispose of it properly.

Last summer, I am re-assembling a small deck I packed about a quarter mile off the road up and out to cliff side on NFS land.  It's a summer vacation spot, perched over a waterfall on some fantastically treacherous terrain with one end on the 45 degree slope, the other end held up level with the help of some trees. I disassemble it and stash it under a tarp like late September through June.  The problem was that my structure made of stainless steel screws and untreated Lowe's dimensional lumber had accumulated a significant amount of mold while it spent 9 months under a tarp during the rainy season, in Oregon's humid coast range air.   I decide to try the copper acetate, because I knew orchards use fungicides which have copper as the most active ingredient, so why not with wood treatment as well?  I applied it with a brush on each surface of each piece of wood, left it to dry, and then did it 2 more times. 3 coats and I might have used quart of liquid on the 8x12' structure. I sanded off the ugly spots of fungus on the visible surface.  Another 5 months under the tarp, and the mold has not reappeared.   Success I think.  Though it might have only needed 1 coat...

Then I started treating a few cedar fence posts with it.  Last high and dry summer, I apply maybe 2 or 3 tablespoons of the stuff to the fence posts near the ground, brush it on heavily so it runs down the post into the ground. Currently my round wood cedar fence posts are only 3 years old and all of them (copper treated and untreated) are still very solid, so I wouldn't yet know if this treatment extends their life.

This stuff is water soluble and probably washes out very quickly under rain.  However, if you have wood you wish to keep mold free, which is not exposed to liquid water flow, I think I would recommend it?  Definitely for protection from humid air, but more experimentation needed for effectiveness in buried earth.  It seems like it would work, if this earth is sheltered from rain and experiences like no ground water flow.  Or maybe it would leech out in a few short years...

This stuff contains copper, which will remain as some form of copper, and thus will increase copper levels in the ground wherever you use it.  On the other hand, plants that grow around the base of the treated posts look just as happy as those as the untreated posts.  Using small amounts of the stuff doesn't appear to have any detrimental effect a cm away from application zone.  I would bet it does not take long (assuming you are not dumping cups of the stuff on the same spot year after year) for the stuff to turn into a less toxic mineral form.

Good luck keeping that gosh darn mold off your wood



 
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I read about a method that is more time consuming, but uses all natural materials. If you pour a few inches of gravel below the post, and then slowly pack layers of clay using a tamper. I guess the clay should be packed so tight that it sounds like concrete when you hit it. Once you get up to ground level with the clay, form a "cone" of clay above the ground so that water will naturally flow away from the post.

It sounds to me like it requires a lot of work, but makes sense that the dense clay will repel water and prevent rot.

I've thought about a method like this for building a fence, where I can take my time and do one post at a time.
 
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