How much does a 6x6 x 8foot cedar post cost?

[Kent A Bathurst]

....... He uses Home Depot PT lumber exclusively and said that it can be painted after drying for about a month. I was deferring to his experience in my "month or two" advice....

Cody - didn't mean to appear to argue that point - was just saying what I would do, and offerring the info provided by a large producer. Locale and climate certainly affect this.

Also, the "tremendous pressure" used to force the chemical into the lumber is usually atmospheric pressure...14.7 psi at sea level. That's because a vacuum is pulled on the cylinder that contains the lumber and then the chemical is introduced. The vacuum is what forces it into the wood.

HOWEVER - heh-heh - I will argue this point. The 50 or so PT plants I have seen don't work the way you describe. 2 reasons are (1) to accelerate the process to decrease cycle time and increase production capacity of a very expensive piece of machinery, and (2) provide more finely calibrated control of the process. They were all built in the past 20 years +/-, so I can't speak to older technology.
> Lumber is loaded on a tram. Tram moves into the cylinder, and door is closed.
> Vacuum is pulled - the purpose is to strip as much moisture out of the cells as possible, leaving them "thirsty" and receptive to the solution, and to provide more control over the process.
> Cylinder is flooded - full - of chemical solution, and put under a hard hydraulic (not atmospheric) pressure, to accelerate the absorption of the solution into the wood. The solution is literally forced into the wood. I realize "tremendous" is a subjective term, but this is way beyond the concept of atmospheric pressure.
> Pressure is released, cylinder pumped empty (not just drained - that's too slow), and another vacuum is pulled to retrieve as much residual solution as possible for reuse ($$$), and to provide control over the solution penetration.

There is more than one reason you would see only 1/2"+ penetration in some lumber. First, heartwood can't be forced to absorb the solution, regardless of how much pressure or how much time. You will usually see this untreated heartwood circle in timbers - 4x4, 6x6, etc. Second, the industry standards for treating require penetration only to a specifiec depth (1/2" last I knew). Understand, though, that if you treat "only" the outer 1/2" of a 2 x 6, you are treating over 70% of the total volume of that stick. Still a lot of water.