How do you store your timber?

[Frank Drew]

A number of years ago now, vacuum drying of timber was being touted as the wave of the future; I haven't heard a thing about it since then I'm not sure what the current state of play is with it nowadays.

Lately, there's a bit of excitement about microwave drying; very high startup costs for the equipment, balanced by very quick turnaround times coupled with good results and fewer of the flaws associated with conventional kiln drying.

May prove a flash in the pan, or may actually turn out to be a viable technique, and one with potentially significant energy savings.

We'll see.

 

[woodbloke]

mrhenderson wrote:

One thing is for sure, and that is that unless the timber has been kiln dried at some point it will NOT be suitable for use indoors

This is a completely incorrect statement. Provided that freshly felled timber is stacked correctly under cover, with a good circulation of air, it will come down to roughly 20% MC, time taken is one year per 25mm of thickness. This is not suitable for use in a modern centrally heated home so a further period of conditioning is needed to bring the MC down to around 10% which is generally accepted to be suitable for indoor use. This secondary drying time can take a lot more than a couple of weeks, more like a couple of months in a moderately warm environment, ie not next to a toasty lounge radiator in the middle of January...a cooler bedroom where the heat is at a minimum (at least in my house, in fact it's off in the winter) is ideal IMO. However it's done, it must be done with some care as too quick and the timber will warp, twist and split as my elm will testify :x - Rob

 

[mister henderson]

mrhenderson wrote:

One thing is for sure, and that is that unless the timber has been kiln dried at some point it will NOT be suitable for use indoors

This is a completely incorrect statement. Provided that freshly felled timber is stacked correctly under cover, with a good circulation of air, it will come down to roughly 20% MC, time taken is one year per 25mm of thickness. This is not suitable for use in a modern centrally heated home so a further period of conditioning is needed to bring the MC down to around 10% which is generally accepted to be suitable for indoor use. This secondary drying time can take a lot more than a couple of weeks, more like a couple of months in a moderately warm environment, ie not next to a toasty lounge radiator in the middle of January...a cooler bedroom where the heat is at a minimum (at least in my house, in fact it's off in the winter) is ideal IMO. However it's done, it must be done with some care as too quick and the timber will warp, twist and split as my elm will testify :x - Rob

We must all speak as we find. However it isnt just the speed of drying that makes timber warp, twist and split, it's the process of drying itself. Wood cannot maintain the same dimensions dry as it can when it is wet. As different parts of the tree hold different amounts of water, there will always be some of the above defects when wood is thoroughly dried.

More info here
http://en.wikipedia.org/wiki/Wood_drying

 

[wizer]

I experienced the stresses in a piece of wood for the first time today. It went into the thicknesser flat and true and as it came out of the other end I saw it warp before my eyes.

 

[woodbloke]

Kilning of timber is an industrial process (not sure when it was first introduced but I assume some time in the late Victorian or early 20cent.) to speed up drying times for commercial operations, time is money etc and a quicker throughput of timber is in everyone's interests who actually needs it.
Which begs the question...what happened in the 'golden age' of english cabinetmaking, reckoned to be in the Regency period, say from 1810 to 1820? This was the time when work was done which has seldom been surpassed, I'm pretty sure that the cabinet makers of the day didn't have access to vast quantities of kiln dried stuff. More likely is that all their timber was carefully air-dried and then used within a cooler environment. Granted, central heating in modern homes does upset these sorts of pieces.
However you slice it, completely air dried timber is suitable for use in modern homes, it just takes a lot longer to bring it down to a suitable moisture level. The elm cabinet I'm doing at the moment is using totally air dried stock and it's taken me a long time with frequent small machinings to bring it to size and more importantly, keep it stable (elm do like to move around a bit :roll: :wink: ) The pic below:

(and apologies to those who've seen it before) is one made from air dried elm and was finished last April, so it's been a year now in a centrally heated house...and there are no sticky drawers - Rob

 

[Sgian Dubh]

It's the heat that forces the wood to give up its moisture

Not quite true mr h. It's the relative humidity combined with heat that causes wood to release moisture quickly in a kiln, plus a means to remove the moisture out of the kiln. For example, a sustained temperature of 90ºC with sustained RH of 75% brings wood down to about 10% MC. True, the end result will almost certainly include severe drying faults such as end splitting or surface checks; case hardening or reverse case hardening; core collapse, honeycombing, etc. Similarly if the wood is stickered up in conditions of 20ºC and 45% RH it will also reach an EMC of 10%, but again there could be drying faults similar to those listed earlier.

Neither of the above sets of conditions are realistic ones for a conventional high temperature wood drying kiln. The basic feature of all kiln schedules is kiln runs begin with lower temperature settings and higher relative humidity values and move towards ever higher temperatures and reduced humidity levels. As an example a kiln run using one of several published schedules for particular species and plank thickness starts with a dry bulb temperature of 35ºC and wet bulb reading of 30.5º C resulting in approximately 70% RH. Through a series of steps the last setting of this kiln schedule are 60ºC dry bulb, 40.5ºC wet bulb resulting in RH an condition of 30%.

I'll also disagree with your assertion that all air dried wood is unsuitable for interior furniture destined for a climate controlled atmosphere. What's required is to bring the air dried boards into a climate that's the same, or very similar to the interior conditions into which the finished object will go into service. Here in the UK air dried wood doesn't usually get much below 20%MC, with about 17% MC the lowest I've seen. The boards should be stickered up in the drier conditions with a decent air flow to bring the MC down to about 9 or 11% prior to working it.

Here's just one more example of air dried wood used for interior furniture. Steam bending is most easily achieved with green wood because it's flexible, and most difficult to achieve with wood kilned to US standards, ie, 7% MC because it's stiffer. The most common compromise is air dried wood at about 20- 22% MC. This is chosen because some of the drying shrinkage and distortion has occurred as the wood is below Fibre Saturation Point (FSP), ie, 30%MC, depending on the species, its extractives content and its structure. Steaming actually hastens drying of the wood and it comes out of the steamer drier than it went in and once the part is bent the wood will be at about 19-20%MC. At that point it's only got to lose about 9 to 10% MC to be in the mid-range of MC it will experience in service. Slainte.

 

[Digit]

This is getting too technical for me. I use a lot of reclaimed timber, air dried, kiln dried, I haven't the slightest idea.
A couple of weeks under the bed and it's machined, and I have had no problems what so ever!

Roy.

 

[Mutley Racers]

Hi, I am looking to make a bit more space in my garage so thinking of building a storage place for timber. Basically off cuts of birch ply etc and studding.

Can anyone recommend a site that tells me how to do this effectively.

Thank you

 

[disco_monkey79]

I store smaller pieces in a purpose-built cavity under my bench. It adds extra heft, so the bench doesn't budge a millimetre when hand planing, etc.

I struggle to lift the bench when empty, so when laden, it isn't going anywhere.