Buy green wood now or in winter?

[Togalosh]

Hello Gents,

I am in need of your help & advice again.

I need to get on with a few projects & so I need to get in a good stock of Larch (& possibly Oak too but this is not so urgent) ... I get my wood from a local saw mill as I do not like dealing with the kiln dried wood suppliers in my neck of the woods due to their impatient/intolerent attitude & the much higher prices...plus the saw mill are a pleasure to deal with & are cheap.

Of course this means I have to season the wood myself - I have read up on this (2 books & countless websites) & think I am ready to build my own dehumidifying kiln (no steam & quite slow). These books assume you have lots of space & time with which to air dry first & then kiln dry. Unforunately my other half has reign over what happens in the garden & wood piles do not feature in her plans.

My main stumbling block is that felling a tree in summer means it's full of sap as opposed to winter felling when the sap has fallen/dropped (?) .. so my questions are:

1) Should I get the timber now & get on with drying it or wait 'til December when it will be dryer?
2) How much more moisture is in the summer wood compared to the winter wood - 50%, 70% ?
3) Would I loose any advantage gained in getting the wood a lot sooner because it would take so much longer to dry?
4) They talk about drying from +_ 20% MC but I'll be starting at a much higher point - is there an issue with this?
5) Must you always dry from 20% MC or is just best practice?.
4) Is there going to be any difference is quality between the 2 ?
5) Is there something I have not even considered/realised that I should know?

As ever I'd apprecaite your input.

Thanks
Togalosh

 

[Richard T]

Hi Tog,

Deciduous trees (Larch included) start to put on a terrific rising of sap as early as February in some cases, Birch for eg. to get their leaves up and running in the spring. Then they continue to run a LOT of water up to the leaves pulled up by transpiration through the sap wood (clue's in the title) but the heart wood is also drawing up water by capillary action as well as absorbing some from the sapwood.

When the leaves are discarded in the autumn (sometimes as late as Christmas if it has been a wet summer) the sap falls as there is no longer the pull from the leaves. In the period when all the leaves have fallen and before the spring push, such trees are dormant and sap has fallen and is not travelling either way. This is the best time to fell to have the least moisture to start with.

So when you buy it doesn't really matter as much as when it was felled and how wet the summer had been beforehand. Deciduous trees have become so to deal with the dryness of cold winters when water is frozen - it is something to deal with lack of water in winter rather than coldness directly. So in a warmer, wetter summer, they will hang on a bit longer and work overtime making the dormant period shorter and the window of felling narrower.

How it is milled is also crucial. As green wood dries it shrinks around its circumference. So a round log is likely to crack in radii pulled apart by shrinkage. The first thing that can be done to counter this is to mill it down the middle along the pith line. Now as the half shrinks it is going to compress the half radius and bow the flat cut side. It may split at the pith but not as much.
The next thing is to quarter it. Quartered, straight trunks are not likely to split at all and boards cut from them will finish much better than if the whole trunk were merely planked.

As well as knowing these basic tricks with wood behaviour, the art of drying well in my experience is to let it happen slowly. Ways of speeding it up are to my mind counter productive and damaging.
Could SWMBO be appeased by a wood store that was more aesthetically pleasing .. a folly facade for eg.?

 

[twothumbs]

Hi. Regarding the 20% thing, I was told many years ago by my then local sawmill, when I askied about MC that all their timber they sold was at 20% (or possibly it was 22%). They couldn't sell it as dried above that. I knew nothing (and know little more now) but there is probably a bit of truth or a mixed-up story here. It may also be linked to dry rot values etc. The wood I got at 1 1/2" was very stable. I bought more than 10 years ago some 2 1/2" and 3" Beech which was wind blown and air dried. It was about 20% but left it for a few months perhaps a year in my garage and it came down to about 16 if I remember rightly, Anyway it has been very stable and has been my bench evet since in the same garage Best wishes.

 

[Bradshaw Joinery]

the best time for felling is between december and february, Sappy wood is harder to dry and requires more conditioning/is more likely to case harden. i think oak is quite good for being kilned straight away, but if it was left to air dry first i think it means avoiding alot of the conditioning process invloved with kiln drying. as the slow drying and absorbtion of moisture during evening hours helps to avoid case hardening.

thats as far as understand it anyway.

 

[Togalosh]

Hiya Richard,

Ways of speeding it up are to my mind counter productive and damaging.

Can you explain how exactly please? David Savage says kiln dried wood has the life sucked from it but I've never seen, felt or worked any wood where I thought that had happened. Most furniture must surely be made from kiln dried wood & the quality of the actual wood is never questioned (in my experience). How is it damaged?

I understand about case hardening & so I plan to 'mist' inside the kiln every few days or so but my plan is also to mimic a warm, breezy day ..the best summers day that has no sunset - so no steam, no temperatures above 35C...just a dehumidifyer & it's own heat or light bulb with thermostat plus some fans.

Waiting 'til Christmas would be a real trial of patience..

SWMBO only has a fairly long but thin garden which packed full of lovely flowers that she is very fond of..besides she's just said "no f*&^&*in way"

PS. I'm still keep to pop round for some Ash (for the mallet handle) when is a good time this week?

Togs

 

[Togalosh]

Hi. Regarding the 20% thing, I was told many years ago by my then local sawmill, when I askied about MC that all their timber they sold was at 20% (or possibly it was 22%). They couldn't sell it as dried above that. I knew nothing (and know little more now) but there is probably a bit of truth or a mixed-up story here. It may also be linked to dry rot values etc. The wood I got at 1 1/2" was very stable. I bought more than 10 years ago some 2 1/2" and 3" Beech which was wind blown and air dried. It was about 20% but left it for a few months perhaps a year in my garage and it came down to about 16 if I remember rightly, Anyway it has been very stable and has been my bench evet since in the same garage Best wishes.

Hello Twothumbs,

20% is the usual figure quoted for air dried timber & that might be needed for firewood...perhaps if it is sold as dried then that must be the level..

20% is the usual starting point I usually get my timer at but I need 8 or 9%. You did the correct thing by waiting & leaving the wood in the room it will be used & 16% is easily reached in a garage but I do not have access to one anymore..and can't wait a year.

Don't get me started on benches..I spent a lovely week on holiday in the sun reading & pondering all things workbench-like & am just as eager to build one of my own..I need more spare time.

 

[Togalosh]

the best time for felling is between december and february, Sappy wood is harder to dry and requires more conditioning/is more likely to case harden. i think oak is quite good for being kilned straight away, but if it was left to air dry first i think it means avoiding alot of the conditioning process invloved with kiln drying. as the slow drying and absorbtion of moisture during evening hours helps to avoid case hardening.

thats as far as understand it anyway.

Hello Olly,

Thanks for your reply..is this problem to do with hot steam kilns or just accelerated drying?

It makes sense about night time absorbtion of moisture ..misting my kiln every night would be a chore...BUT ha! we've just taken down a misting system from the factory where my workshop is (it was a print works & so needed a constant level of humidity). It was a simple system so I could easily reuse it.. I wondered how many people it made ill over the years.

Togs

 

[Richard T]

Just ring me or PM Steve, any time this week is fine.