Still thinking about how to preserve natural posts

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?

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.

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.

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.