I was microwaving a piece dry this AM and got to wondering. Since
several woodturners have vacuum pumps, has anyone tried vacuum drying
wood? Should work, just need a decent pump and a good bell jar. At a
low enough pressure the water would boil out, I would think similar to
microwaving. Ought to be faster as you don't have to worry about
scorching the wood. Pull a vacuum and leave it be for a bit.

Maybe another reason to give SWMBO as to why I need a vacuum pump.

--
Bill Berglin

"Life should not be a journey to the grave with the intention of
arriving safely in a pretty and well preserved body, but rather to skid
in broadside, thoroughly used up, totally worn out, and loudly
proclaiming, 'WOW! What A RIDE!!" ... Unknown

"Bill B" wrote in message
news
I was microwaving a piece dry this AM and got to wondering. Since several
woodturners have vacuum pumps, has anyone tried vacuum drying wood? Should
work, just need a decent pump and a good bell jar. At a low enough
pressure the water would boil out, I would think similar to microwaving.
Ought to be faster as you don't have to worry about scorching the wood.
Pull a vacuum and leave it be for a bit.

Maybe another reason to give SWMBO as to why I need a vacuum pump.


You run into problems with vacuum drying. You have to keep bleeding the
vacuum and the wet air out of the system. Also, since you're not providing
heat to the process, the bonds binding the water to the cellulose are not
going to let loose as fast, because they are at lower energy.

Since wood dries by losing moisture, the rate of which is determined by the
relative humidity, it seems the smart money would go for direct control of
that, rather than the indirect methods.

"Bill B" wrote: (clip) Pull a vacuum and leave it be for a bit. (clip)
^^^^^^^^^^^^^^^^
Here's what will happen: You pull a vacuum, which removes air and water
vapor from the chamber. Water evaporates from the wood and comes to
equillibrium with the wood at the same partial pressure as though the air
were present. Even though your gauge shows you still have a good vacuum,
there's noting going "dryingwise." So you would have to keep the pump
running, or starting and stopping it at intervals. If the humidity where
you live is low, you could probably dry the wood just as fast by letting it
sit on a shelf or in a pile.

I'd do it slowly - don't want a large bubble to explode.
I'd think of doing it in a light finishing oil or light cooking oil maybe.
It will keep the water out and will replace the water once the vac is reduced.

Martin Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
NRA LOH, NRA Life
NRA Second Amendment Task Force Charter Founder



Bill B wrote:
I was microwaving a piece dry this AM and got to wondering. Since
several woodturners have vacuum pumps, has anyone tried vacuum drying
wood? Should work, just need a decent pump and a good bell jar. At a
low enough pressure the water would boil out, I would think similar to
microwaving. Ought to be faster as you don't have to worry about
scorching the wood. Pull a vacuum and leave it be for a bit.

Maybe another reason to give SWMBO as to why I need a vacuum pump.


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
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When you work on an air conditioning system you "vacuum it down" after you
close it back up. The moisture is discharged through the vacuum pump outlet
in vapor form. If I recall you have to exceed 27" or even 29" (30" perfect?)
before any "boiling/vaporizing" begins. You will go far below RH or EMC.
Automotive repair equipment works just fine on auto sized systems.

A problem would be constructing the perfect enclosure since the tiniest
vacuum leak defeats the process preventing you from achieving the 27" or so.
I'm sure there must be industrial pumps and systems.

TomNie


"Bill B" wrote in message
news
I was microwaving a piece dry this AM and got to wondering. Since several
woodturners have vacuum pumps, has anyone tried vacuum drying wood? Should
work, just need a decent pump and a good bell jar. At a low enough
pressure the water would boil out, I would think similar to microwaving.
Ought to be faster as you don't have to worry about scorching the wood.
Pull a vacuum and leave it be for a bit.

Maybe another reason to give SWMBO as to why I need a vacuum pump.

--
Bill Berglin

"Life should not be a journey to the grave with the intention of arriving
safely in a pretty and well preserved body, but rather to skid in
broadside, thoroughly used up, totally worn out, and loudly proclaiming,
'WOW! What A RIDE!!" ... Unknown

There are threads in our archives re drying wood by vacuum drying and
freeze drying, also by osmotic pressure. As far as I know these methods
have never been of any use for woodturners due to physical and economic
problems.

I guess if there are many solutions to the drying problem, it probably
means that there is no one best method ...or just maybe the problem
hasn't been solved.


Turn to Safety, Arch
Fortiter



http://community.webtv.net/almcc/MacsMusings

"Arch" wrote in message
...
There are threads in our archives re drying wood by vacuum drying and
freeze drying, also by osmotic pressure. As far as I know these methods
have never been of any use for woodturners due to physical and economic
problems.

I guess if there are many solutions to the drying problem, it probably
means that there is no one best method ...or just maybe the problem
hasn't been solved.


Turn to Safety, Arch
Fortiter



http://community.webtv.net/almcc/MacsMusings

====Et tu, Archus Fortitus! 8^(

Have you all ready forgotten that LDD eliminates those complex forms of
methodism?

Leif

Sorry Soapy, my abject apology. Of course LLD is the one best solution.
"'In Detergent, Veritas" or to be PC,
"E Pluribus Unum"


Turn to Safety, Arch
Fortiter



http://community.webtv.net/almcc/MacsMusings

oops, I meant LDD! Let's keep the lawyers out of this.


Turn to Safety, Arch
Fortiter



http://community.webtv.net/almcc/MacsMusings

Arch,

OK - let me add something I saw at the library at Arrowmont. The Woodturning
Masters Class, I think, by Tony Boase showed a couple times a huge rough
bowl being dried with a heat gun (hair dryer?) from the outside. These were
the famous "masters" at work.

Makes me wonder if one of those infra-red heaters next to the bowl while
turning would help. Get a woodturner's tan if nothing else.

Another thing would excite George and start some ..... Turn the bowl up to
over 3000rpm and just let it fling the water out for awhile. Sorta like LDD
without the soap.

TomNie


"Arch" wrote in message
...
There are threads in our archives re drying wood by vacuum drying and
freeze drying, also by osmotic pressure. As far as I know these methods
have never been of any use for woodturners due to physical and economic
problems.

I guess if there are many solutions to the drying problem, it probably
means that there is no one best method ...or just maybe the problem
hasn't been solved.


Turn to Safety, Arch
Fortiter



http://community.webtv.net/almcc/MacsMusings

Tom Nie wrote:
Arch,

OK - let me add something I saw at the library at Arrowmont. The Woodturning
Masters Class, I think, by Tony Boase showed a couple times a huge rough
bowl being dried with a heat gun (hair dryer?) from the outside. These were
the famous "masters" at work.

Makes me wonder if one of those infra-red heaters next to the bowl while
turning would help. Get a woodturner's tan if nothing else.

Another thing would excite George and start some ..... Turn the bowl up to
over 3000rpm and just let it fling the water out for awhile. Sorta like LDD
without the soap.

TomNie


"Arch" wrote in message
...

There are threads in our archives re drying wood by vacuum drying and
freeze drying, also by osmotic pressure. As far as I know these methods
have never been of any use for woodturners due to physical and economic
problems.

I guess if there are many solutions to the drying problem, it probably
means that there is no one best method ...or just maybe the problem
hasn't been solved.


Turn to Safety, Arch
Fortiter



http://community.webtv.net/almcc/MacsMusings





With the right jack pulley, you could get 10,000 rpm, not even the bugs
could hang in there then :-)

--
Bill Berglin

"Life should not be a journey to the grave with the intention of
arriving safely in a pretty and well preserved body, but rather to skid
in broadside, thoroughly used up, totally worn out, and loudly
proclaiming, 'WOW! What A RIDE!!" ... Unknown

"Tom Nie" wrote in message
...

Another thing would excite George and start some ..... Turn the bowl up
to over 3000rpm and just let it fling the water out for awhile. Sorta like
LDD without the soap.


Compressed air from the inside will eject unbound water with much greater
safety. Won't work well on the small spots of face grain, of course. What
it will do is cut down on the growth of mildew, especially if you use an
occlusive coating on wet wood. I don't use the coating, but the air helps
get a light wood to dry with no mildew spots.

As to drying, if you think of it, you're not gaining more than a week of dry
time. It's the bound water that counts, and since end grain dries ten times
faster than face anyway, and application of mechanical energy won't speed it
up loss of bound water....

On Fri, 7 Oct 2005 08:47:24 -0500, "Leif Thorvaldson" wrote:


"Arch" wrote in message
...
There are threads in our archives re drying wood by vacuum drying and
freeze drying, also by osmotic pressure. As far as I know these methods
have never been of any use for woodturners due to physical and economic
problems.

I guess if there are many solutions to the drying problem, it probably
means that there is no one best method ...or just maybe the problem
hasn't been solved.


Turn to Safety, Arch
Fortiter



http://community.webtv.net/almcc/MacsMusings

====Et tu, Archus Fortitus! 8^(

Have you all ready forgotten that LDD eliminates those complex forms of
methodism?

Leif

it's just that all those soap bubbles clog the vacuum pump...


mac

Please remove splinters before emailing

On Fri, 7 Oct 2005 17:22:13 -0400, "Tom Nie" wrote:

Arch,

OK - let me add something I saw at the library at Arrowmont. The Woodturning
Masters Class, I think, by Tony Boase showed a couple times a huge rough
bowl being dried with a heat gun (hair dryer?) from the outside. These were
the famous "masters" at work.

Makes me wonder if one of those infra-red heaters next to the bowl while
turning would help. Get a woodturner's tan if nothing else.

Another thing would excite George and start some ..... Turn the bowl up to
over 3000rpm and just let it fling the water out for awhile. Sorta like LDD
without the soap.

TomNie

Tom.. "spin drying" is fairly common.. I learned it here...

Last spring, when I was turning a lot of very wet pine that had been under the
snow during the winter, it helped a lot..

I'd rough turn it at normal speed, which would already have the shop wall and
ceiling soaked, then turn it up to the highest rpm I thought was safe and let it
fling any left over water out... and LOTS of additional water got flung... (some
early attempts got my wife's wood burning stuff wet and led to re-aiming be
pivoting the lathe)




mac

Please remove splinters before emailing

"Bill B" wrote in message
news
I was microwaving a piece dry this AM and got to wondering. Since
several woodturners have vacuum pumps, has anyone tried vacuum drying
wood? Should work, just need a decent pump and a good bell jar. At a
low enough pressure the water would boil out, I would think similar to
microwaving. Ought to be faster as you don't have to worry about
scorching the wood. Pull a vacuum and leave it be for a bit.

Maybe another reason to give SWMBO as to why I need a vacuum pump.

--
Bill Berglin

"Life should not be a journey to the grave with the intention of
arriving safely in a pretty and well preserved body, but rather to skid
in broadside, thoroughly used up, totally worn out, and loudly
proclaiming, 'WOW! What A RIDE!!" ... Unknown

The problem with vacuum drying is that you have to remove the moisture from
the enclosure without letting the vacuum escape. Normally this is done by
having a very cold pipe run thru the enclosure, with a drain gutter below
it. Captured moisture then drains (by gravity) into a chamber with valves
above and below. To release the moisture, the top valve is closed, the
bottom valve then releases the trapped moisture. Then the bottom valve is
closed and the top valve is opened to start the process again. Commercial
vacuum kilns do this automatically.

So not only do you have to have a vacuum-proof container, a vacuum pump, but
you also have to run a refrigeration system and associated piping, etc. Not
so simple a deal.

Regards,
James Johnson