How do you air dry your wood down to 20% ??

[difflock]

Well I tested a few conifer logs at random from my open fronted and draughty shed just now,

13.5% to 15% (and it was snowing outside when I tested them) 

Compared to the selection that have been toasting below the stove for a few weeks, most of which are giving a very consistent 8.5%.

Cheers

mth

Edited February 25, 2020 by difflock

[Big J]

6 minutes ago, difflock said:

Well I tested a few conifer logs at random from my open fronted and draughty shed just now,

13.5% to 15% (and it was snowing outside when I tested them) 

Compared to the selection that have been toasting below the stove for a few weeks, most of which are giving a very consistent 8.5%.

Cheers

mth

 

I'd check your moisture metre. There isn't any way the MC could be that low. Looking at the general forcast for central NI, the average relative humidity is just over 90% (and has been all winter). It's very unlikely it's below 20% and I'd guess it'd be 22-23%. The equilibrium moisture content it 22.2%, and whilst it might be carrying a bit of summer gained dryness, I'd hazard a guess that you've had plenty of 100% RH days that will have knocked it right up.

 

I'm not being pedantic, but just had to point out that in the UK that sub 20 in winter is very tough to achieve and sub 15 is impossible.

[difflock]

11 minutes ago, Big J said:

 

I'd check your moisture metre. There isn't any way the MC could be that low. Looking at the general forcast for central NI, the average relative humidity is just over 90% (and has been all winter). It's very unlikely it's below 20% and I'd guess it'd be 22-23%. The equilibrium moisture content it 22.2%, and whilst it might be carrying a bit of summer gained dryness, I'd hazard a guess that you've had plenty of 100% RH days that will have knocked it right up.

 

I'm not being pedantic, but just had to point out that in the UK that sub 20 in winter is very tough to achieve and sub 15 is impossible.

Which I included the 8.5% for the "toasty" sticks below the fire, being aware that my bought-off-ebay  "CEM DT-129" moisture meter could well be mis-reading, a little. 

It also gives 99.8%/99.9% when tested in wet water.

Can you suggest any easy way to calibrate it?

Edited February 25, 2020 by difflock

[Big J]

25 minutes ago, difflock said:

Which I included the 8.5% for the "toasty" sticks below the fire, being aware that my bought-off-ebay  "CEM DT-129" moisture meter could well be mis-reading, a little. 

It also gives 99.8%/99.9% when tested in wet water.

Can you suggest any easy way to calibrate it?

I don't know. I had a fairly pricey Delmhorst meter when I had the sawmill, but I left that with the business.

 

The issue is that even with a windy site, the air can only carry the moisture that it has capacity for. So 90% RH at 30mph (a stiff breeze) and 5c can still only carry 0.56g of water per cubic meter of air until saturation point is reached. Obviously, that metre cube of air moves quickly in a breeze, but even so, it'll still only dry as low as equilibrium moisture content and no further.

[Woodworks]

57 minutes ago, difflock said:

Which I included the 8.5% for the "toasty" sticks below the fire, being aware that my bought-off-ebay  "CEM DT-129" moisture meter could well be mis-reading, a little. 

It also gives 99.8%/99.9% when tested in wet water.

Can you suggest any easy way to calibrate it?

Try an over dry test or if you feel brave a microwave drying test which is very quick but can end in combustion if not closely observed haha

[difflock]

47 minutes ago, Woodworks said:

Try an over dry test or if you feel brave a microwave drying test which is very quick but can end in combustion if not closely observed haha

O.K.

I shall pop a small piece of wood in the oven the next time the wife has it on, and leave it overnight in the decaying heat.

Cheers

mth

Though I suspect the alogrithm may "break down" as one aproaches 0.00% moisture content.

Edited February 25, 2020 by difflock

[Rob_the_Sparky]

I think the point is measure it before going in the oven, then calculate the real percentage from the weight before and after drying.  Then compare the two...

[difflock]

16 minutes ago, Rob_the_Sparky said:

I think the point is measure it before going in the oven, then calculate the real percentage from the weight before and after drying.  Then compare the two...

?

Measure it or weight it  .  .  .

Edited February 26, 2020 by difflock

[Rob_the_Sparky]

Use the meter to take a moisture measurement before putting in the oven.  Then weigh the wood.  Put wood in the oven to dry it out and weigh again at the enf.  This gives you the dry weight and wet weight of the wood so you can calculate the moisture % of the wood before it went in the oven to compare with your meter measured value.

[openspaceman]

1 hour ago, difflock said:

?

Measure it or weight it  .  .  .

weigh it. I cut a piece as near under 30g and weigh it on a postal scale, note the weight and stick it in the microwave for 1 minute. note the weight let it cool a bit if it is steaming and repeat until you observe no further reduction. that stable weight is then the oven dry weight and it should pick up a gram or so over the next few hours. The original moisture content is the original weight  minus oven dry weight divided by the original weight.