I normally keep a couple of 2 liter cokes in the fridge. But this
evening I had to resort to ice cubes since I'd forgotten to restock
my cold coca cola supply. The ice cube tray was "full" - with
half cubes. Hmmmmm - the tray was filled with water a month
or two ago.
Freeze dried . . . Hmmmm.
Anyone pop a green piece in the freezer - for a couple of weeks
and check the weigth change?
charlie b
My thoughts have been towards Vacuum Drying of Timber anyone had ago at
this?
RVS
http://www.laymar-crafts.co.uk
"charlie b" <char...@accesscom.com> wrote in message
news:4445F1...@accesscom.com...
Water -expands- as it freezes. Enough said?
Freeze Drying, uses cold and a vacuum.
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"charlie b" <char...@accesscom.com> wrote in message
news:4445F1...@accesscom.com...
Actually, freeze drying involves freezing, heating, and vacuuming all at the
same time. See: http://home.howstuffworks.com/freeze-drying.htm
Small units are not expensive. The FPL does not mention it.
Woodweb says its a bad idea, but then goes on to say it can work.
http://www.woodweb.com/knowledge_base/Alternative_lumber_drying_techniques.html
Vacuum kilns involve heating the wood, which can be the tricky part.
http://www.woodweb.com/knowledge_base/Vacuum_kiln_drying.html
Dan
Sublimation: Passing from solid state to gaseous state directly
without
going through the liquid state.
In a "frost free" freezer, the "gas", in this case water vapor, is
removed
from the freezing compartment - if it wasn't it would condense and
become
"frost". So there is some removal of water - directly from ice.
OR - IF the liquid dishwashing detergent (LDD) method actually gets
the solution INTO the wood, I doubt it would freeze.
> but
> you also will have an Expansion of Water when Frozen = to 9% of its volume,
> this may distort/destroy the Inner Cell Structure of the Wood?
>
As for the unusual characteristic of water - to expand, rather than to
contract, as it cools, (good thing too or we and other liquid water
based
organisms would never have occurred on this planet) - I believe the
expansion value is closer to 4%. That's in the expansion range of
many
common woods - something solid wood furniture makers have been dealing
with for quite a while (imagine trying to make chairs in Egypt).
But back to quick (relative to air drying) drying - perhaps to
eliminate
the the "ice cracking" potential problem, how about just using the
refridgerator part of the fridge?
charliel b
It is more about the Breaking or Rupturing of Cells, that when the Wood is
Thawed and the Moisture Removed [Freezing will not remove Internal Moisture
by Sublimation] there is a very real risk of Collapse within the Wood.
In a nut shell we are not discussing a Viable Method for Drying Wood so its
back to the proven methods or the Soap Bath.
RVS
"charlie b" <char...@accesscom.com> wrote in message
news:444677...@accesscom.com...
Ok I said I'm sorry, so back to the subject. I think lyopholizing,
ionizing radiation and hypertonic osmotic gradients have all been tried
and found not feasible for drying or preserving turning timber. Not to
say that some other methods are that much better. :)
Turn to Safety, Arch
Fortiter
I've turned wood frozen for five months at lower temperatures. No
difference, because it's not the freeze that counts, it's that frost-free
fan that takes the high relative humidity cold air out. It's evaporation,
same as all the other things you mention, that dries the wood. If the
surface looses faster than can be replaced from within, the wood checks.
Look at a piece of meat that's got "freezer burn" if you want to know what's
going to happen to the wood.
"Freeze-drying" in commercial parlance has more to do with vacuum than
temperature. http://home.howstuffworks.com/freeze-drying.htm Vacuum
drying is used with wood.
Vic Wood in Australia says that they use freeze drying regularly. You put the
wood in the freezer long enough to let it fully freeze (probably a few days).
You then remove it from the freezer and place it in the refrigator and let the
fan draw out the moisture. This takes several more days. (You should weigh it
each day until it stops loosing weight.) Now they were using this for rough
turned bowls. My wife and I have tried this with some success, when we can find
room in our freezer, which is seldom.
Incidentally, one trick I learned from the World of Wood, the magazine of the
International Wood Collector's Society, in an article it says to stand the wood
vertical in the way that it grew and there will be minimum checking. We've tried
this with some Madrone pieces about 5 feet long. They have been standing for six
months now with little or no cracking. This is only one trial. The information
supposedly came from an old logger, who said to stand your sawn boards on end
while they dry and there will be minimum warping and checking. It isn't going to
be fast, but it may be a way to save your collected timber from self
destruction.
Fred Holder
<http://www.fholder.com>
In article <444677...@accesscom.com>, charlie b says...
--
NewsGuy.Com 30Gb $9.95 Carry Forward and On Demand Bandwidth
Bound water would not freeze. Unbound water would require a temperature far
lower than the home freezer unit. Remember your HS chemistry where they
talked about freezing point depression in solutions? Then, of course,
there's no way cellulose cell walls are going to break, not that they need
to, there being no live tissue inside, and holes in them anyway.
> The Scientific facts are Water at 0°C in Liquid form has a density of
> 0.9999grams per cubic centimetre where as Ice at 0°C has a Density of
> 0.9150g/cm³ which equates to 9% the damage this can do when trapped is well
> known, how many of you have suffered a Burst Water Pipe?
The Scientific fact of the matter is - the analagy is not scientific at
all. The anatomy (cellular structure) of the xylem and phloem in any
plant, and especially the hardwoods, is extremely complex and far
stronger and more flexible than household pipe. Nor is the liquid
contained in the living tissue water. It is a complex mixture of
solutes in water that changes both the freezing point and properties of
the system. Moreover, there is both bound and free water in wood.
Think about it, northern trees experience repeated cycles of freezing
and thawing each spring and fall. Green wood cut isn't so different
from green wood in the tree.
>
> In a nut shell we are not discussing a Viable Method for Drying Wood so its
> back to the proven methods or the Soap Bath.
>
Actually, we are. My shop is located in an unheated barn. Winter
temperatures range from below freezing to below zero. I routinely cut
slabs from green wood and allow them to dry while frozen. Rough turned
blanks sit on the floor covered by shavings frozen. They are repeately
subjected to thaw/freeze cycles as I heat the workshop to work and then
let it go back to sub freezing. I have experienced NO cracking that
wasn't due to wind shakes. I even tried putting the pith dead center
through both sides in a number of blanks to see what would happen.
Either no or minimal cracking. My experience is that it works.
It's also been reported on other message boards that putting a green,
rough turned blank into the freezer for several days/weeks prevents
both cracking and to some extent warping/distortion. So it's working
for other people as well.
You need to take a look at the molar concentration of sap and the
freezing point depression per mole.
...
>
> Incidentally, one trick I learned from the World of Wood, the magazine of the
> International Wood Collector's Society, in an article it says to stand the
> wood
> vertical in the way that it grew and there will be minimum checking. We've
> tried
> this with some Madrone pieces about 5 feet long. They have been standing for
> six
> months now with little or no cracking. This is only one trial. The
> information
> supposedly came from an old logger, who said to stand your sawn boards on end
> while they dry and there will be minimum warping and checking. It isn't going
> to
> be fast, but it may be a way to save your collected timber from self
> destruction.
..
Considering how easily Madrone cracks, it's an interesting data point
I remember HS chemistry, something about rearranging letters & numbers
separated by an arrow and a little about a piece of chicken wire with
the same symbols attached with equal signs at the corners. It was
taught by the same man who taught us shop (we had a Delta lathe) and
typewriting and I didn't learn much, so rcw helps me with all three. :)
Freezing point depression makes it highly unlikely he can freeze the sugar
water in the wood.
http://dbhs.wvusd.k12.ca.us/webdocs/Solutions/BP-Elev-and-FP-Lower.html If
you could, and if there was any alteration in wood structure because of it,
there wouldn't be a tree left standing in the north, where it gets much
colder than any freezer made for commercial use. That's why the tree
reduces the amount of water it contains in the winter, to concentrate the
solution, and make the freezing point lower. The fan, of course removes
humidified air, which accelerates water loss. Leave out of the freezer, and
you'll get the same.
Note also, as in the other posts, that water escapes at a lower rate in a
cool situation.
> Look at a piece of meat that's got "freezer burn" if you want to know what's
> going to happen to the wood.
This analogy doesn't "hold water", scientifically : ). Muscle and wood
tissue, while both complex cellularly, are vastly diffierent
structurally, physiologically, and chemically. Way too much to go into
here. You are correct that the process that produces freezer burn is
surface dehydration. However, due to a number of factors related to
the cellular structure of muscle, movement of subsurface water to the
surface is virtually nonexistant while frozen. The cellular structure
of wood is far more conducive to water movement along the grain while
frozen. Freezer burn is a film of cell destruction covering the
surface, while checking is separation of tissue along stress lines with
minimal cell damage. The two are nothing alike.
Also, differences in elasticity, plasticity, compressive strength, etc,
etc, etc make any comparison between muscle and wood tissues a
non-starter, except in Biology classes. The properties that
distinguish the difference between muscle and wood tissues are huge.
We don't burn t-bones to barbecue mesquite and trees can't walk. : )
When all is said and done, a fair number of people have successfully
used freezing to prevent checking, myself included. I don't think
anyone claims that it works for all species of wood, under every
condition that could exist. But it does work, at least under some
conditions, for some species of wood.
Say what? It's loss of moisture and structural collapse. Lipid isn't
cellulose and vice versa, but you certainly can see that the _loss of
moisture_ which expands the structure is the common thread. Or are you just
trying to sound important?
Capillary action, the process by which unbound water is carried by the tree,
or pulled by evaporation, depends on adhesion to the walls of the tube, and
cohesion of the liquid involved. What happens to the surface of wood where
the relative humidity is low is that it loses water to the air to the degree
the air is able to accept it which cannot be replaced from the interior by
capillary action. That's what causes surface checking - always - and the
weakness in structure from the collapse of fibers which have lost their
bound water produces initial surface checks, which open until adhesion
overcomes cohesion, preventing capillary draw.
Proof is in your woodpile. End checks are self-limiting. Once the dry
layer is thick enough, it isolates the interior from further rapid loss,
which is why you can trim off the damaged ends and find wood well above the
EMC in the interior. Wet the end, re-expand the fiber, and be fooled into
thinking the structure is sound to your sorrow.
>
> When all is said and done, a fair number of people have successfully
> used freezing to prevent checking, myself included. I don't think
> anyone claims that it works for all species of wood, under every
> condition that could exist. But it does work, at least under some
> conditions, for some species of wood.
>
I have cord upon cord of wood which has been "frozen" all winter, and it's
only now beginning to dry again. Since the water couldn't leave, the
checks have not grown. Is that what you mean by preventing checking? It
may seem news to you, but loggers have known it for years. Keeping the log
submerged or soaked will do the same thing, and for the same reason.
However, none will have done a thing to prevent checks which will begin on a
freshly exposed surface once water can be removed. That's the drying part.
Take two pieces of wood, as nearly identical as you can get. Make them
from the same stick. Freeze one, not the other, then put them into
identical conditions to dry and check for difference. I suggested this to
Fred when he spoke of alcohol "drying" as an effective method. There will
be no difference in dry time nor in distortion. Of course, if you control
the relative humidity by wrapping, as in the "alcohol method" you will have
success, if you toss them on the table for three days at 60% RH, you will
have failure. Freeze has nothing to do with it - nor does alcohol. It's
controlled moisture loss which is the independent variable in your
experiment.
Try it.
a method used to prepare bio specimens for scanning electron microscopy
(SEM) is to replace all of the water in the tissue with alchohol, followed
by liquid CO2. The specimen is submerged in liquid CO2, and thressure and
temp are cranked up to the triple point (the point where the CO2 gas/liquid
phase lines and temperature pressure phase lines intersect) -. Basically at
this point, the CO2 transisions from liquid to gas, but the volume does not
change. If you remember your basic chemistry.physics, and think about gas
laws, it should make sense. If you don't remember it, just take my word for
it - its real.
the end result (in bio anyway) is a speciment that is totally dry, but with
none of the distortion (shrinking) usually assoicated with liquid loss.
It seems that (in theory anyway) this should work for dessicating wood. I
don't know how good the wood would be....0% moisture just doesn't sound like
it would be a good thing. (Bio specimens in this state are delicate beyond
delicate). Course, all the bio SEM work I've done was in specimens that were
in the 5 mm or less size range, so you'd have to be doing some mighty small
woodwork.....
this is what happend when a engineer/bio geek starts thinking.......
--JD
> Capillary action, the process by which unbound water is carried by the tree,
> or pulled by evaporation, depends on adhesion to the walls of the tube, and
> cohesion of the liquid involved.
Actually this mechanism has been proved to be insufficient to explain
how water is transported to the tops of redwoods, for example.
> What happens to the surface of wood where
> the relative humidity is low is that it loses water to the air to the degree
> the air is able to accept it which cannot be replaced from the interior by
> capillary action. That's what causes surface checking - always - and the
> weakness in structure from the collapse of fibers which have lost their
> bound water produces initial surface checks, which open until adhesion
> overcomes cohesion, preventing capillary draw.
>
Incorrect, actually. Has nothing to do with structural collapse of
fibers. Wood shrinks differentially as it dries, setting up stresses
that pull the wood apart.
> Proof is in your woodpile. End checks are self-limiting. Once the dry
> layer is thick enough, it isolates the interior from further rapid loss,
> which is why you can trim off the damaged ends and find wood well above the
> EMC in the interior. Wet the end, re-expand the fiber, and be fooled into
> thinking the structure is sound to your sorrow.
>
Very poor analogy. We are talking of properly prepared blanks, pith
removed and roughed out to a thickness of about 3/4" to 1 1/2" not
firewood. Apples and oranges.
>
> Take two pieces of wood, as nearly identical as you can get. Make them
> from the same stick. Freeze one, not the other, then put them into
> identical conditions to dry and check for difference. I suggested this to
> Fred when he spoke of alcohol "drying" as an effective method. There will
> be no difference in dry time nor in distortion. Of course, if you control
> the relative humidity by wrapping, as in the "alcohol method" you will have
> success, if you toss them on the table for three days at 60% RH, you will
> have failure. Freeze has nothing to do with it - nor does alcohol. It's
> controlled moisture loss which is the independent variable in your
> experiment.
>
> Try it.
I have. It works. Both freezing and alcohol. And actually you are
quite wrong about the effect of alcohol. It's used quite extensively
in the preparation of tissue for microscopy. The alcohol replaces the
water, i.e., dehydrates the tissue, preventing damage or distortion of
the tissue. Freezing is likewise used extensively to microtome fresh
samples for immediate viewing rather than permanent mount.
Perhaps you are, deliberately or subconciously, missing the critical
point. No one is saying to cut a block of wood with pith running
through it, put it in the freezer or in alcohol, pull it out and expose
it to low humidity and expect it not to check. What we are saying is
that if you rough turn a green wood blank to about an inch wall
thickness, freeze it or soak it in alcohol long enough for the water to
be replaced by the alcohol, and then dry the blank slowly (under cover
of shavings or in a paper bag or other method of your choice), the
failure rate from checking will be drastically reduced if not
eliminated and you can dry more quickly than would be the case without
treatment.
Cool idea - nanoturning. I can appreciate as a bio & computer geek.
Don't think there would be much of a market though.
Gee that's interesting. Maple syrup is far more concentrated (I'm not
sure of the actual ratio but I think it takes 30-40 gal of sap to make
1 gal of syrup) and it freezes just fine either in the fridge or chest
freezer downstairs.
Well all this might be true, but the highest antifreeze rate is not
found at the highest concentration level !!
Have fun and take care
Leo Van Der Loo
I see we have an English problem. Moisture expands the structure, loss
comes after.
No point in going further. You're not interested, or incapable.
Bark's even a better insulator than wood. That's what the folks that study
it say. Tree concentrates solutes by going dry(er) come winter. Makes it
tough to freeze the only living part. Even tougher to freeze the interior.
If you're simple and contentious like ebd, you gloss over all that ionic
stuff.
Of course, the tree doesn't waste valuable sugar on the heartwood. Phenols,
phenyls, tannins, other things keep that from freezing easily. Not that it
can't happen. Does, but it's in the big numbers below zero. Trunk sort of
explodes, as if struck by lightning when it reaches its elastic limit. Saw
it in Alaska while doing winter survival at Fairchild.
--
I'm not sure how long a block that size it might take in the fridge
freezer (and even in the chest freezer). Outside in my unheated
barn/shop, where it sits for days below freezing, I'm pretty sure it
would freeze solid. A roughed out blank will freeze rather quickly,
even in the refrigerator freezer. An inch of wood, particularly wet
wood, doesn't provide much insulation.
"George" <George@least> wrote in message
news:44476...@newspeer2.tds.net...
>> In a nut shell we are not discussing a Viable Method for Drying Wood so its
>> back to the proven methods or the Soap Bath.
>>
>
>Actually, we are. My shop is located in an unheated barn. Winter
>temperatures range from below freezing to below zero. I routinely cut
>slabs from green wood and allow them to dry while frozen. Rough turned
>blanks sit on the floor covered by shavings frozen. They are repeately
>subjected to thaw/freeze cycles as I heat the workshop to work and then
>let it go back to sub freezing. I have experienced NO cracking that
>wasn't due to wind shakes. I even tried putting the pith dead center
>through both sides in a number of blanks to see what would happen.
>Either no or minimal cracking. My experience is that it works.
I'm going to have to throw in an anecdotal agreement. Whether it's a
nice thing to do to the wood or not, I left a big pile of willow in my
backyard all winter and it froze solid for at least two or three
months. Since the weather has improved, I've got it sawn into blanks
and set to dry in the shed, but I've turned a bunch of it with nice
results.
>It's also been reported on other message boards that putting a green,
>rough turned blank into the freezer for several days/weeks prevents
>both cracking and to some extent warping/distortion. So it's working
>for other people as well.
Oddly enough, I hadn't thought of it, but in the case of the willow
mentioned above, it's been less prone to warping and cracking after it
froze and rethawed. I had attributed it to improving technique, but
I'm not doing anything all that different. Could be on to something,
could be nothing, but living in Wisconsin, I'll just keep storing
stuff in unheated buildings and if it works, great!
"Arch" <al...@webtv.net> wrote in message
news:27913-444...@storefull-3176.bay.webtv.net...
Hard to get willow to crack at all, in my experience. Whole family of
cottonwood/willow/poplars are bulletproof in drying.
I got a few cracks right away, but not many- so it's likely that's the
case. Good news for me, anyhow. Now if only it smelled a little
better....
Sadly, even if you get it wet later, like when setting the fuzz prior to
final sanding, it'll smell like willow again.
Great ornament wood, with the shimmer and low weight, though.