How quickly do super dry logs take up moisture?

[Woodworks]

We often discus the merits of kiln dried logs and how dry they are when it comes to using them. Wood is hygroscopic so will end up in equilibrium with the environment they get stored in. Kiln dried logs can be very dry but how quickly will they take up moisture again when they are put in a damp environment like an outside log shed?

 

I have oven dried a beech log until it loses no more weight so should now be at 0% moisture. I took a moisture meter reading before drying to partly test the accuracy of my meter. It read 20% on one end and 17% on the other. This log is left over from last season so has had two years drying.

 

Starting weight 655 grams

 

Dry weight 543 grams

 

So the meter was close with the log being 20.6% before oven drying.

 

It's now going into a covered log shed to see how quickly it takes on water again.

[Alycidon]

Like the meter, any details ?,

 

A

[se7enthdevil]

it'll be an interesting experiment beau but you must remember that it will depend entirely on the species and also how humid the air is in the first place.

 

stick a hygrometer in the area you are going to test it and check periodically what the humidity is.

 

try this using a range of species and get an average between the lot.

 

oak (varying common species)

beech (spalted and unspalted)

ash

elm

sycamore

hornbeam

birch

maple

hawthorn

horse chestnut

sweet chestnut

cherry

apple

 

 

if you can test all these perhaps with the common softwood species as well you will get an accurate result.

[openspaceman]

 

Starting weight 655 grams

 

Dry weight 543 grams

 

So the meter was close with the log being 20.6% before oven drying.

 

It's now going into a covered log shed to see how quickly it takes on water again.

 

Will you weigh it every week or so?

 

My guess is it will reabsorb moisture slower than it lost it as temperatures are lower for the moisture to migrate but will be interested to see.

[Justme]

Going on the recommendation of letting wood you are going to use in a house be left in the room for a week or two I would expect it to show signs quite quickly.

[Woodworks]

it'll be an interesting experiment beau but you must remember that it will depend entirely on the species and also how humid the air is in the first place.

 

stick a hygrometer in the area you are going to test it and check periodically what the humidity is.

 

try this using a range of species and get an average between the lot.

 

oak (varying common species)

beech (spalted and unspalted)

ash

elm

sycamore

hornbeam

birch

maple

hawthorn

horse chestnut

sweet chestnut

cherry

apple

 

 

if you can test all these perhaps with the common softwood species as well you will get an accurate result.

 

Yes for perfection you are right Steve but this is just a bit of fun really. I might do some ash and oak as well as this would cover the majority of what I see going for firewood.

[Woodworks]

Like the meter, any details ?,

 

A

 

20 year old Protimeter. It came with a calibration test and adjustment tables for the various species. Never had cause to doubt it.

[Woodworks]

Will you weigh it every week or so?

 

My guess is it will reabsorb moisture slower than it lost it as temperatures are lower for the moisture to migrate but will be interested to see.

 

Sure it will take longer than the drying. Amazed how quick you can oven dry a log. Just a few hours and it was done.

[openspaceman]

Sure it will take longer than the drying. Amazed how quick you can oven dry a log. Just a few hours and it was done.

 

Yes because the relative humidity of the air in the oven is very low, so it has lots of capacity for absorbing more moisture from the log plus the heat delivered into the log vaporises the water so it comes out as steam.

 

In the winter the RH is high but that's because the air hasn't much water capacity and being cold water shouldn't migrate into the wood as fast, but we'll see.

[rowan lee]

Amazed how quick you can oven dry a log. Just a few hours and it was done.

 

Oven dried logs Beau. Now there's a little cottage industry waiting to happen. How much could you charge for a net of that?