Moisture Meter

[geoff]

In message , robgraham writes

You seemed to be moaning about the fact that it had to be done at all

No, someone else said that, I pointed out that they had

I didn't I just said that's how it should be done

Well, I've given my opinion and the reasons behind them

If you're too precious to take it on board without sulking like a kid, that's your problem, not mine

[mail]

Dear AJH Impressive... general chemist or specialist wood chemistry? re

******* RE the op's question; I think these moisture meters with probes are simple resistance meters, they depend on the electrical path through hydrated salts in the wood?? *******

Twin probe ones are, indeed, resistance meters. (There are also capacitance and radio wave ones.) I suspect that you will be measuring the resistance of the wood structure mainly cellulose Beta

1:4 linked glucose 2000 units long - with the not disimilar hemicellulose which when there is no water in the wood (105 C for 48 hrs) would be high and when there is lots of water both in the wall and the lumen then you will get conductivity. I imagine that the meter is thus inverted so that it gives a "high" reading when resistance is low. What actually causes a reduction in resistance would I suspect be salts in the water rather than the wood but you may be right. Chris

[Tim Lamb]

In message , AJH writes

Ah! Thank you.

Defects? This is meadow land timber with who knows how many generations of farmers fencing staples buried. The intention is to provide enough material to build the framing for a 20'x 40' single storey barn. At present, I have 4 lengths of Oak trunk 10' long by 3' dia. I can get another 20' without bothering the forestry commission.

You will have to translate *Hft*. Forestry acronyms are less understandable than most. What is a board foot for example?

regards

[Stuart Noble]

As has been said, the moisture level on the surface is no guide at all, and the prongs on the cheap meters won't penetrate without breaking. The ones they use in sawmills are hammered into the logs, and are built accordingly. The only way to get accuracy with a cheap model is to crosscut a 6" or so length of log, then split it down the middle, then immediately test the faces. This doesn't take the resin content into account, which I would guess is what's causing the original problem, and drying doesn't remove that. In kiln dried timber you can often see it bleeding from the end grain.

[geoff]

In message , Stuart Noble writes

[AJH]

Hoppus foot, the traditional way of measuring hardwoods, 27.736 per m^3 IIRC. It's a round measure that aims to indicate how much sawn wood the log will yield.

merkinism

12" x 12" x 1"

Defects include knots, inclusions, shakes ( laminar separation I suppose), cross and spiral grain.

AJH

[Tim Lamb]

In message , AJH writes

Ah. So if I divide your 150Hft guess by 27 I get an answer in cubic m of round wood? OK.

All of those but this is eye candy construction with the roof load carried elsewhere.

regards