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

[Rough Hewn]

I think unless you've been able to protect the timber from the elements over winter, that 10% is impossible. The lowest we ever had over winter was mid 17s on beech in the airdrying barns and 12-13 in the scorching summer (2018). That's with meticulous stacking and a £350 moisture meter. 
 
You'll get a grace period going into winter from the dryness acheived over summer, but at this stage in winter, the equilibrium moisture content is fairly consistently 20%. Some years it was 23% for us near Edinburgh.

It is in a barn, tested with magnetic field meter.
And he's OCD about stacking[emoji23]

[emoji106][emoji106][emoji106]

[Rough Hewn]

It must be spectacularly well protected from the elements. That being said, I think I've moved from one very wet part of the country to another and we never saw below 17% in winter on our stacks

Devon is pish wet.
I grew up going camping on Dartmoor.
Every camping trip since, not on the moors is so nice and easy.
50mph wind rain sleet fog and that was in summer.
[emoji106][emoji106][emoji106]

[Woodworks]

10 hours ago, Rough Hewn said:

Devon is pish wet.
I grew up going camping on Dartmoor.
Every camping trip since, not on the moors is so nice and easy.
50mph wind rain sleet fog and that was in summer.

Yes and we get bad weather in winter ?

Edited February 27, 2020 by Woodworks

[openspaceman]

3 hours ago, Big J said:

I think unless you've been able to protect the timber from the elements over winter, that 10% is impossible. The lowest we ever had over winter was mid 17s on beech in the airdrying barns and 12-13 in the scorching summer (2018). That's with meticulous stacking and a £350 moisture meter. 

I know where you're coming from and @Woodworks is saying much the same but here in Sunny Surrey I was pulling softwood from my log shed in the low teens , I've very little left to test but I'll look to do a test.

3 hours ago, Big J said:

 

You'll get a grace period going into winter from the dryness acheived over summer, but at this stage in winter, the equilibrium moisture content is fairly consistently 20%. Some years it was 23% for us near Edinburgh.

Yes but as I mentioned some posts back the equilibrium moisture content verses relative humidity is not a line but an area bounded by two ogives, one is the path  the drying takes as timber dries and the other as it readsorbs moisture, I have found an image from a research paper on mahogany as an illustration, so it is to illustrate the principal only:

 

Equilibrium moisture content of mahogany wood as a function of relative humidity at 25°C. Filled and open symbols correspond to the adsorption and desorption states, respectively. 

 

 

If you interpolate using 90% RH as the average maximum humidity a log will experience in the middle of a stack ( given that it takes time for the whole log to reach equilibrium) you will see it settles at 16% mc but the same log being dried from green settles at 19%. Again there is the problem is that the basis on which the moisture content is being measured is not stated.

 

What it means is that the water from 25% down is weakly bonded to the wood structure and energy is needed to release the water molecules from that bond hence the drying line is higher than the wetting line.

[xdcx]

Lad here on the Facebook selling dry ready to burn hardwood saying it is all "mostly below 25%". I'm pretty good with my stove but I don't relish the challenge of getting that stuff going. Life is too short.

This thread made me go for a little looksy around Facebook and Gumtree for the local and semi local area just as a wee experiment. Vast majority of what you see for sale and what is being sold/re-listed with more stock etc is all hardwoods. Birch/elm mostly. One lad selling some nice looking Ash actually and I have ended up contacting him.... bloody internet!!

 

But yeah I find it incredible that with the abundance of softwood cut sites around me right now, all of which are spruce, pine, larch! That it's almost pretty hard to find any soft in amongst the troves of h/wood. Goes to show the guys selling are appealing to the dumbing off the masses. Which I of course do not blame them for but I just don't get this mentality.  

[openspaceman]

12 hours ago, openspaceman said:

16 hours ago, Big J said:

I think unless you've been able to protect the timber from the elements over winter, that 10% is impossible. The lowest we ever had over winter was mid 17s on beech in the airdrying barns and 12-13 in the scorching summer (2018). That's with meticulous stacking and a £350 moisture meter. 

I know where you're coming from and @Woodworks is saying much the same but here in Sunny Surrey I was pulling softwood from my log shed in the low teens , I've very little left to test but I'll look to do a test.

Okay I've tested a piece of Wellingtonia that went in the shed, on the floor, February 19, it was fresh felled and I reported here at the time the moisture content was 75%, today it came out at 25% but the bit I split off prior to testing burst into flames immediately when I put it in the stove. The piece of hardwood, beech, went in sometime in winter 19, green and today was 21%. I guess left to another summer they would continue to lose moisture but because of space considerations I will not season stuff more than one summer before I burn it. These pieces coming from the floor or near the bottom will not have dried as well as stuff nearer the glass roof.

 

In the meanwhile this morning  my neighbour took delivery of a cut and split load of ash from the local log merchant, I asked her for permission to weigh a bit and it was at 31%.

 

NB because of the small sample size  and accuracy of my kitchen scales I would allow +- 5% variance on these figures.

[Rob_the_Sparky]

They are just selling what there is demand for.  Same effort to go to the woods and get hardwood as softwood, pretty much the same effort to cut and split and you can sell hardwood for more money so if you can get hardwood to sell why wouldn't you if there is more profit in hardwood?  Then as you say there is the demand problem for softwood.  All of this is good news for those of us happy to process our own logs and happy to burn softwood.

[Stere]

This docu has a loads of graphs and infos on wood moisture ans seasoning etc.....

http://www.biomasstradecentre2.eu/data/upload/D5_5_Manual_firewood_production_biohousing.pdf

 

 

 

 

[xdcx]

22 hours ago, Rob_the_Sparky said:

 All of this is good news for those of us happy to process our own logs and happy to burn softwood.

Nail on head!

[openspaceman]

12 hours ago, Big J said:

 

21% is where I'd expect beech to be after 12 months in undercover log storage.

Okay but I would expect to get it lower  I think I need to look at some airflow under my stack, trouble is that will lose me some volume.

12 hours ago, Big J said:

 

No retailer can afford to dry firewood for two years,

Which is why some people kiln dry, it can mean a lot in cashflow terms

12 hours ago, Big J said:

 

and 21% burns perfectly well.

I agree but there is also little doubt drier burns better, again it's BATNEEC and the damage this does to the woodland management could potentially  be counter productive .

 

The reasons behind the legislation is that a target has been set for PM2.5, the powers that be have  set that target without considering the implication that many respiratory problems stem from long previous exposures and also that the alleged contribution of PM2.5 from burning firewood is largely from burning purchased firewood when in fact things like bonfires  are also lumped in with the "domestic fires" portion.

 

The reason "domestic fires" now allegedly account for 30% along with 30% from unknown sources is that industrial stacks and transport have been cleaned up to a fraction of the 1970 levels. Particulate levels have reduced to about 20% of their 1970 levels overall, a lot of it from loss of heavy industry.

12 hours ago, Big J said:

 

I would bet that it was a touch lower than 21% before the start of winter though, as beech dries so quickly.

Now that is illogical, here in SE England the equilibrium moisture content settles about 17% so nothing is likely to rise above that, what has happened is the conditions in the stack mean the log did not become below 20% before winter set in.

 

To illustrate this I picked out 2 pieces of oak and one piece of bay that were left from the previous year but otherwise in the same shed, the oaks were 17% and 19% and the bay 14% ( but it was quite well buried in the pile and high against a side) so as I said my conclusion is that if I can get the logs dry enough in a summer than they will not adsorb moisture to any worrying amount.