Drying timber


T

Tim Lamb

Having spent the last two days converting some *seasoned in the round*
lumps of Oak to 4"x4"x4' lengths I now have a pallet stacked with some
rather wet wood.

I also have a redundant domestic de-humidifier. Can the group foresee
any problems with putting the two together under a tarpaulin?
Clearly the waste heat will raise the local ambient temperature but so
what?

regards
 
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G

Grunff

Tim said:
Having spent the last two days converting some *seasoned in the round*
lumps of Oak to 4"x4"x4' lengths I now have a pallet stacked with some
rather wet wood.

I also have a redundant domestic de-humidifier. Can the group foresee
any problems with putting the two together under a tarpaulin?
Clearly the waste heat will raise the local ambient temperature but so
what?
As long as the dehumidifier is able to get the waste heat away from
itself, it should work fine. To achieve this, make sure there's plenty
of space around the dehumidifier - aim for a tent, rather than a draped
tarp.
 
W

Weatherlawyer

Tim said:
Having spent the last two days converting some *seasoned in the round*
lumps of Oak to 4"x4"x4' lengths I now have a pallet stacked with some
rather wet wood.
You say it was seasoned but it is still wet? I take it it has been
stacked for an year?
I also have a redundant domestic de-humidifier. Can the group foresee
any problems with putting the two together under a tarpaulin?
Clearly the waste heat will raise the local ambient temperature but so
what?
It'll crack if you don't know what you are doing.

Oak takes an year per inch to dry in air. You paint the ends to stop
the end grain cracking. You will get twists and shakes cooking it too
quickly.

Did you know enough about sawing it to make sure the wayne edge has
been removed? Don't worry too much if not. The stuff can be treated
with preservatives to good effect.

With oak, the white outer layer might be 2 or 3 inches thick. As it is
the oak will curve around the knots as it dries.

I really wouldn't be tempted to dry it any quicker than you need to.

Before seasoning a tree, it was usually stacked in a river for the
water to rinse out any unused sap. It would then be stored for an year
or more before converting. After that it would depent on what was
wanted from it.

Obviously if a shipwright bought it, he would cut and shape the timber
-even steam it, before working it. I believe it would then be seasoned
in mud. Not too sure about that though.

Perhaps that was both a way of preserving it and keeping the stock
viable for use on contracts not yet ready for it.
 
O

owdman

De-humidifier is fairly normal way to season wood on a small scale -
there should be loads of info if you google. The basic ground rule
whatever method you use is to not do it too quickly.

cheers

Jacob
 
T

Tim Lamb

In message said:
You say it was seasoned but it is still wet? I take it it has been
stacked for an year?
Oh yes. More like fifteen. This was a massive hedgerow Oak that stood
dead for some years before blowing over. The base was rotted and too
heavy to move (around 3 tons) so it is providing homes for Stag beetles
etc.
The rest was logged and stacked.

With the *barn job* requiring some replacement studs, I thought I might
see if any of this was fit to use. For single storey and with a 3' dwarf
wall I only need a bit over 4' lengths so I tried to avoid significant
knots.

Rot is an issue. Radial splitting has allowed water and spores in which
may mean much is useless. Mind you, pre-rotted timber should match the
rest of the barn!
It'll crack if you don't know what you are doing.
Too late:)
Oak takes an year per inch to dry in air. You paint the ends to stop
the end grain cracking. You will get twists and shakes cooking it too
quickly.
Yes. I have started oversize to cater for modest movement. My time scale
is more like 4 weeks
Did you know enough about sawing it to make sure the wayne edge has
been removed? Don't worry too much if not. The stuff can be treated
with preservatives to good effect.
If the question was how do you convert 24"+ logs into usable sizes with
an 18" bar chain saw and an ancient 12" bench saw, the answer is, very
slowly. Some was 1/4 sawn, some I took an 8" slab out of the middle.
Either way the circular saw was very unhappy: requiring lots of
re-sharpening and the operator lots of tea.

Do you have a recommendation on preservative? I suppose I have to
consider possible future uses and avoid anything hazardous to humans.
With oak, the white outer layer might be 2 or 3 inches thick. As it is
the oak will curve around the knots as it dries.

I really wouldn't be tempted to dry it any quicker than you need to.
Hmm.

Before seasoning a tree, it was usually stacked in a river for the
water to rinse out any unused sap. It would then be stored for an year
or more before converting. After that it would depent on what was
wanted from it.
I doubt there was any sap there before it fell over. I have several more
in a similar state but still standing.

This may just be a colossal waste of time but it is something I wanted
to do and so far hasn't cost anything.

regards
 
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T

Tim Lamb

Grunff said:
As long as the dehumidifier is able to get the waste heat away from
itself, it should work fine. To achieve this, make sure there's plenty
of space around the dehumidifier - aim for a tent, rather than a draped
tarp.
OK. See reply elsewhere for the rest of the story.

regards
 
T

The Natural Philosopher

Tim said:
Having spent the last two days converting some *seasoned in the round*
lumps of Oak to 4"x4"x4' lengths I now have a pallet stacked with some
rather wet wood.

I also have a redundant domestic de-humidifier. Can the group foresee
any problems with putting the two together under a tarpaulin?
Yes. Many many problems

Accelerated drying of wood leads to the surface drying out, with then
checks and cracks, ..these may or may not close up by the time the wood
settles to an average RH content.

The correct way to season wood is to paint the ends of the baulks to
prevent too fast evaporation, and stack for at least one year per inch
thickness.

Kiln drying can accelerate this, but not by that much.

Since your timber is pre seasoned (lord knows how they stopped it
cracking at trunk sizes) it won;t be as bad, but I'd still leave it in
the environment its to be used in for several months before
finishing..if you intend to strip it into planks. do that roughly now,
and then stack and leave.


Best of all immediately but the definitive book 'Understanding Wood' by
Hoadley, and study it. He really knows his stuff and there is nothing
better on the market in terms of using wood as an engineering and craft
material than that.
 
T

Tim Lamb

The Natural said:
Yes. Many many problems
My first concern was whether the heap will burst into flames:)
Accelerated drying of wood leads to the surface drying out, with then
checks and cracks, ..these may or may not close up by the time the wood
settles to an average RH content.
It has already done most of those.

If I were cabinet making you would be quite correct and I wouldn't have
started from here. As it is, I need to assemble the barn framing in
about a months time. Fair facing and cutting tenons will be left to the
last to minimise the effects of movement. It is possible that I will get
the material grit blasted to artificially age before final assembly.
The correct way to season wood is to paint the ends of the baulks to
prevent too fast evaporation, and stack for at least one year per inch
thickness.
Tempus fugits....

I must go and see how hot the tent has got.

regards
 
T

The Natural Philosopher

Tim said:
My first concern was whether the heap will burst into flames:)

It has already done most of those.

If I were cabinet making you would be quite correct and I wouldn't have
started from here. As it is, I need to assemble the barn framing in
about a months time. Fair facing and cutting tenons will be left to the
last to minimise the effects of movement. It is possible that I will get
the material grit blasted to artificially age before final assembly.
Ok,. so we can treat it as 'green timber'

Now I have a house made of green oak, 4 years old and STILL drying out.

Its perfectly OK to use in this condition, provided you realise that the
timber will lose about 10% of its dimension across the grain and about
1% down the grain, over the next 4 years.

With careful design you can minimize the worst effects of this, but you
cannot eliminate it.

What this means is that pinned mortice/tenon joints will end up loose
and gappy over time. Plaster that used to abut beams will end up with up
to a fingers width gap.

My solution has been to decorate roughly, leave, and go back and caulk.
and fill after a time period.

Don't bother with doing anything to the timber at all. Just whack it up
with the above in mind, and leave decoration and plastering as long as
possible.

A few days forced drying out will make no appreciable difference to the
overall shrinkage, and may cause unecessary stress anyway.

And you anyway tend to get +-1% variation summer to winter across the
grain with ANY wood.
 
P

Pete C

My first concern was whether the heap will burst into flames:)

It has already done most of those.

If I were cabinet making you would be quite correct and I wouldn't have
started from here. As it is, I need to assemble the barn framing in
about a months time. Fair facing and cutting tenons will be left to the
last to minimise the effects of movement. It is possible that I will get
the material grit blasted to artificially age before final assembly.


Tempus fugits....

I must go and see how hot the tent has got.
Hi,

Watch out for 'case hardening:

<http://www.google.co.uk/search?hl=en&q=wood+"case+hardening"&btnG=Google+Search&meta=>
<http://groups.google.co.uk/groups?q=wood "case hardening"&hl=en&lr=&sa=N&tab=wg>
<http://groups.google.co.uk/groups/search?hl=en&lr=&q=wood+"case+hardening"+dehumidifier&qt_s=Search>
<http://www.google.co.uk/search?hl=e...rdening" dehumidifier&qt_s=Search&sa=N&tab=gw>

Probably best to keep the humidity high initially.

cheers,
Pete.
 
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T

Tim Lamb

The Natural said:
Ok,. so we can treat it as 'green timber'

Now I have a house made of green oak, 4 years old and STILL drying out.

Its perfectly OK to use in this condition, provided you realise that
the timber will lose about 10% of its dimension across the grain and
about 1% down the grain, over the next 4 years.
I'll skip the inter-stud plaster board then. No sense trapping moisture.
I think the only issue with across grain shrinking will be where windows
are fitted between two uprights.
With careful design you can minimize the worst effects of this, but you
cannot eliminate it.

What this means is that pinned mortice/tenon joints will end up loose
and gappy over time.
Hmm. I hadn't planned to pin intermediates, assuming gravity and the
roof will hold the frame together. There appears to be no strapping
securing the sole plate to the dwarf wall which may excite some future
building control person.
Plaster that used to abut beams will end up with up to a fingers width
gap.
I think this can wait until the final use is determined. A bit domestic
for a workshop.
My solution has been to decorate roughly, leave, and go back and caulk.
and fill after a time period.

Don't bother with doing anything to the timber at all. Just whack it up
with the above in mind, and leave decoration and plastering as long as
possible.

A few days forced drying out will make no appreciable difference to the
overall shrinkage, and may cause unecessary stress anyway.
Oh. I thought it might help if the wood was encouraged to settle down
before final working.
And you anyway tend to get +-1% variation summer to winter across the
grain with ANY wood.
OK Thanks.

regards
 
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T

Tim Lamb

Pete C said:
Hi,

Watch out for 'case hardening:
Right. In fact the air in the tent is barely above ambient. The
de-humidifier had collected 1/2 litre or so of water but this is not a
sealed chamber so a small amount of air is filtering in anyway. I'll
have a look tomorrow and decide whether to abandon the extra drying and
simply wait until I actually need the wood for final machining or
continue.

regards
 

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