Chile Forum

o.k., so I finally bought a moisture meter on Amazon. In Chile, there are just endless uses for it, especially considering we do a lot of evaluating homes for our clients to purchase. Also firewood is often so wet, you don't need a meter to test it. Your hand will be wet, if you touch the inside of newly split log.

So, thought I would share my first adventure at Sodimac Constructors in Puerto Montt the other day. The guys working their were really curious too as to just how dry everything was they were selling (I like the guys at sodimac).

First, almost everything that was marked "seco" or dry came in at the percent they claimed or below. For example all the standard 2x4 I tested came in at 12% to 15%. Many even came in at around 8% to 10 %, but then also the probes did not go very deep.

All the stuff marked for bulk, discount, or verde for sale came in at over 18%, most at around 20-25%, and some went off the charts which for my meter was 50% (mostly inside the middle of the pile).

What did catch me by surprise was the wood that was impregnated. I tested a bunch of treated 2x4's and they came in at 20% or more. A few were so wet, I could just tell by the way the probes sunk in to them that they would hit the top end of the meter. You think they would use drier wood, since the moisture was going to be trapped inside.

I think the impregnated wood is treated with copper sulphate, isn't it? Isn't copper sulphate hygroscopic?

Cheers,

James.

I think I might have made that up, actually (in particular, I remember now that copper sulphate is blue), but the question still applies as to whether whatever copper compound the wood is impregnated with attracts moisture.

Update: A quick Web search suggests it is actually chromated copper arsenate (hence an old post I remember you making, suggesting it is toxic for domestic construction). Whether or not it's hygroscopic seems to be the subject of some research I found citations for, but it appears not to be obviously so...

jehturner wrote:I think I might have made that up, actually (in particular, I remember now that copper sulphate is blue), but the question still applies as to whether whatever copper compound the wood is impregnated with attracts moisture.

Update: A quick Web search suggests it is actually chromated copper arsenate ...

That's right -- mostly Wolman CCA which is the chromated copper arsenate as you indicated, widely used in Chile and subject to an EPA ban in the US and apparently a number of other countries, largely due to the arsenic component.

The replacements include ACQ treatment which involve reactive and corrosive components, and the waterborne inorganic salts used in the ACQ treatment are believed to be significantly hygroscopic.

I also use a hygrometer, a Delmhorst that I got from Amazon dot com. Essential when preparing lenga flooring since lenga can take so long to dry.

setting aside if it is toxic or not (likely is), I have seen a lot of the treated lumber is not treated all the way through. Thus, you would expect it to rot from the inside out, especially if you should need to cut it.

My general inclination and way I was raised is to only use treated lumber in places that will not come in contact with humans or animals on a daily basis. So, like I would avoid it for things like pick-nick table or kids playhouse (use to see those in the states as a kid all the time), but have no problem using it for fence posts.