mel jacobson on fri 24 sep 99
industry does have moisture meters that measure
the exact content of moisture in wood.
many saw mill operators, manufacturers, wood workers...will
have the meter.
\they are not our of range expensive.
just costly.
now i will probably have to go and get one.
let kurt pay for it.
his eye is bad again.
going back for a re/do...will keep you posted.
not real worried.
just a little.
mel/mn
http://www.pclink.com/melpots
from minnetonka, minnesota, u.s.a.
Steve Dalton on sat 25 sep 99
Mel,
Maybe you should stop poking him in the eye with that sharp stick!
Just remember what your mother always said...
it's only fun until someone's eye get poked out!
Just giving you a bad time! Hope everything goes
better this time around!
Steve Dalton
----------
> From: mel jacobson
> To: CLAYART@LSV.UKY.EDU
> Subject: wet wood
> Date: Fri, 24 Sep 1999 10:22:55 EDT
>let kurt pay for it.
>his eye is bad again.
>going back for a re/do...will keep you posted.
>not real worried.
>just a little.
>mel/mn
>
>http://www.pclink.com/melpots
>from minnetonka, minnesota, u.s.a.
Dave Finkelnburg on sat 25 sep 99
Mel,
I don't want to reduce the market for electronic devices. However, for
a lower cost approach, why not simply weigh a sample of the wood,
dry it at about 250 degrees F until bone dry, then weigh it again? You
don't want to heat it so much as to drive off anything but the water, so the
lower drying temperature is better. This test is at least as accurate, if
not more so, than the meter, and affordable!
Thanks for your recent advice on thermocouple placement in my kiln. I
have done it!
Good firing!
Dave Finkelnburg in windy southern Idaho
dfinkeln@cyberhighway.net
-----Original Message-----
From: mel jacobson
To: CLAYART@LSV.UKY.EDU
Date: Friday, September 24, 1999 8:23 AM
Subject: wet wood
----------------------------Original message----------------------------
industry does have moisture meters that measure
the exact content of moisture in wood.
many saw mill operators, manufacturers, wood workers...will
have the meter.
\they are not our of range expensive.
just costly.
now i will probably have to go and get one.
let kurt pay for it.
his eye is bad again.
going back for a re/do...will keep you posted.
not real worried.
just a little.
mel/mn
http://www.pclink.com/melpots
from minnetonka, minnesota, u.s.a.
Maid O'Mud Pottery on sun 26 sep 99
This note was struck me as extremely humorous. "a sample of wood" - we use wood
to heat, and I can tell you for a fact that when one is hand splitting wood, no
two pieces are even close to being the same size. This test only works if all
pieces are the same (or very close) in size.
Sounds like "city folk" advise to me.
Sorry to poke fun, but I'm still ROFL.
Dave Finkelnburg wrote:
> ----------------------------Original message----------------------------
> Mel,
> I don't want to reduce the market for electronic devices. However, for
> a lower cost approach, why not simply weigh a sample of the wood,
> dry it at about 250 degrees F until bone dry, then weigh it again? You
> don't want to heat it so much as to drive off anything but the water, so the
> lower drying temperature is better. This test is at least as accurate, if
> not more so, than the meter, and affordable!
--
sam - alias the cat lady
SW Ontario CANADA
http://www.geocities.com/paris/3110 scuttell@odyssey.on.ca
"First, the clay told me what to do
Then, I told the clay what to do
Now; we co-operate"
sam, 1994
Janet Kaiser on mon 27 sep 99
----------------------------Original message----------------------------
>Mel,
> I don't want to reduce the market for electronic devices. However, for
>a lower cost approach, why not simply weigh a sample of the wood,
>dry it at about 250 degrees F until bone dry, then weigh it again? You
>don't want to heat it so much as to drive off anything but the water, so
the
>lower drying temperature is better. This test is at least as accurate, if
>not more so, than the meter, and affordable!
> Dave Finkelnburg in windy southern Idaho
> dfinkeln@cyberhighway.net
>
>-----Original Message-----
>industry does have moisture meters that measure
>the exact content of moisture in wood.
>
>many saw mill operators, manufacturers, wood workers...will
>have the meter.
>\they are not our of range expensive.
>just costly.
>now i will probably have to go and get one.
>let kurt pay for it.
>his eye is bad again.
>going back for a re/do...will keep you posted.
>not real worried.
>just a little.
>mel/mn
>
>http://www.pclink.com/melpots
>from minnetonka, minnesota, u.s.a.
Feel a real expert on this :-) coming from wet Wales, where houses are on
average over 100 years old, built of stone and ALWAYS have damp problems...
I can tell you that nearly everyone we know owns an inexpensive and nifty
device that you wet wood burners should get (a lot cheaper than drying out
wood to check every time or getting an expensive device).
I is a small battery powered gizmo with two metal prongs that you jab at the
wall/ceiling/floor - and I do not see why not kiln wood? - to get the
"wetness" level reading. Your own experience will soon tell you what the
acceptable reading on the dial would be.... It does not work on percentages,
but from a flimmer of action at the white end of the dial (no moisture)
through to buzzing, dancing, really worrying, wet red.
You could check every single piece of wood, split them down the middle or
take samples and cross sections... Create a new job for someone who is into
hydro-whatever at each firing (No! Don't shoot... only kidding! :-)
Check out the do-it-yourself stores. Here in the UK they are next to the
pipe, wire and cable detectors. Cost around US$10 (plus batteries).
Hope it helps? And for all you naked potters, you can have fun checking out
your own body moisture levels... Just watch out where you jab the detector!
Janet Kaiser
The Chapel of Art, home of The International Potters Path
Criccieth, GB-Wales, UK
http://www.the-coa.org.uk
postbox@the-coa.org.uk
Ray Aldridge on mon 27 sep 99
At 11:38 AM 9/26/99 EDT, you wrote:
>----------------------------Original message----------------------------
>This note was struck me as extremely humorous. "a sample of wood" - we
use wood
>to heat, and I can tell you for a fact that when one is hand splitting
wood, no
>two pieces are even close to being the same size. This test only works if
all
>pieces are the same (or very close) in size.
>
>Sounds like "city folk" advise to me.
>
>Sorry to poke fun, but I'm still ROFL.
I don't mean to spoil the fun, but can you explain why you think all the
pieces have to be exactly the same size? This is a relative test. Doesn't
matter if the wood weighs one pound or two pounds-- you're taking a
percentage. If you're saying that wood of different sizes drys at
different rates, this really only applies if the pieces are dried
separately and the size differences are very substantial. But in the real
world, wood is dried in a rick, pieces packed together, and after a couple
of months in a covered rick, the moisture content of a piece three inches
in diameter will be pretty similar to one four inches in diameter, because
of their close proximity while drying. Of course, there will be a
difference between unsplit logs and logs split into kindling, but you could
still weigh logs of similar size or kindling of similar size, and come
pretty close. Of course, wood of different species will dry out at
different rates (and burn at different caloric rates) but if you have a
truckload of slabs you've been drying out under cover for 6 months, the
test should work perfectly well, no matter how big a length you use.
Anyway, that's how it seems to me, and I've had three wood kilns and lived
for years in a house with no electricity and no heat source other than
wood. But I could be wrong-- I frequently am.
Ray
>
>Dave Finkelnburg wrote:
>
>> ----------------------------Original message----------------------------
>> Mel,
>> I don't want to reduce the market for electronic devices. However, for
>> a lower cost approach, why not simply weigh a sample of the wood,
>> dry it at about 250 degrees F until bone dry, then weigh it again? You
>> don't want to heat it so much as to drive off anything but the water, so
the
>> lower drying temperature is better. This test is at least as accurate, if
>> not more so, than the meter, and affordable!
>
>--
>sam - alias the cat lady
>SW Ontario CANADA
>http://www.geocities.com/paris/3110 scuttell@odyssey.on.ca
>
>"First, the clay told me what to do
> Then, I told the clay what to do
> Now; we co-operate"
>sam, 1994
>
Gavin Stairs on tue 28 sep 99
I know I'm piling on, but I just thought I'd add to the dry-it-and-weigh-it
discussion.
There is a procedure in analytic chemistry called drying to constant
weight. You take a sample of whatever, weigh it, and chuck it in the
dessicator. Then you take it out after a while and weigh it again. Then
back into the dessicator, and so on. You plot all your weights and keep
doing this until two or more weights come out the same. You look at the
plot and see a nice monotonically descending curve like an exponential
(sorry about the big words: pretend I just mumbled something inaudible).
If you don't, you accuse your lab mate of fooling with your samples.
Of course, in a complex material like wood, there is more than one drying
curve. And the drying curve will differ according to how thick the piece
is, and how hot you dry it, and the relative humidity of the air, and the
atmoshperic pressure, etc. So you may not see a constant weight for quite
some time.
But such a procedure will tell you if you can economically kiln dry your
wood, and will eventually tell you the water content. I advise using thin
wood samples, preferably with lots of end grain showing.
Gavin
Maid O'Mud Pottery on tue 28 sep 99
Ray:
In my real world, we collect deadwood from a neighbouring property. It is a mix
of oak, maple, beech, etc. Sizes vary wildly from spindly branches to trunks ov
3 feet across. Age of the wood? Unknown. Covered? HA!
We use our nose, fingers and good sense to tell when the wood is ready to burn.
Dried wood? You mean, you PAY for the wood to heat your home? Slabs - oh no, I
off laughing again.
No harm meant - just trying to get folks to see that wood is available from all
different sources - and there are no absolutes....as with working with clay.
Ray Aldridge wrote:
> ----------------------------Original message----------------------------
> At 11:38 AM 9/26/99 EDT, you wrote:
> >----------------------------Original message----------------------------
> >This note was struck me as extremely humorous. "a sample of wood" - we use
> wood to heat, and I can tell you for a fact that when one is hand splitting
> wood, no two pieces are even close to being the same size. This test only wor
> if all pieces are the same (or very close) in size.
> >
> >Sounds like "city folk" advise to me.
> >
> >Sorry to poke fun, but I'm still ROFL.
>
> I don't mean to spoil the fun, but can you explain why you think all the
> pieces have to be exactly the same size? This is a relative test. Doesn't
> matter if the wood weighs one pound or two pounds-- you're taking a
> percentage. If you're saying that wood of different sizes drys at
> different rates, this really only applies if the pieces are dried
> separately and the size differences are very substantial. But in the real
> world, wood is dried in a rick, pieces packed together, and after a couple
> of months in a covered rick, the moisture content of a piece three inches
> in diameter will be pretty similar to one four inches in diameter, because
> of their close proximity while drying. Of course, there will be a
> difference between unsplit logs and logs split into kindling, but you could
> still weigh logs of similar size or kindling of similar size, and come
> pretty close. Of course, wood of different species will dry out at
> different rates (and burn at different caloric rates) but if you have a
> truckload of slabs you've been drying out under cover for 6 months, the
> test should work perfectly well, no matter how big a length you use.
>
> Anyway, that's how it seems to me, and I've had three wood kilns and lived for
> years in a house with no electricity and no heat source other than
> wood. But I could be wrong-- I frequently am.
>
> Ray
--
sam - alias the cat lady
SW Ontario CANADA
http://www.geocities.com/paris/3110 scuttell@odyssey.on.ca
"First, the clay told me what to do
Then, I told the clay what to do
Now; we co-operate"
sam, 1994
I.Lewis on fri 1 oct 99
------------------
Gavin Stairs seems to be having some trouble with those long words. Must say=
I
was fascinated with =22monotonically descending curve like an =
exponential=22.
Now I think I know what he means from the context of his posting but is the =
word
he is looking for Asymptotically, meaning that it only approaches but never
reaches a steady value. The difference is so small that it is almost
unmeasurable.
I really do like Monotonically. In a poetic sense it is a fair description, =
a
boring line. Almost as boring as the process of desiccation.
One notion which has not been mentioned, or so it would seem unless I have
missed something, is the additional calorific value of wet wood due to the =
Water
Gas reaction. Above about 1100Celsius, superheated steam reacts freely with
carbon to give free hydrogen and carbon monoxide. So wet gas striking those
white hot coals in the fire box can give free combustible gas which promotes
increasing temperature as it burns with secondary air and the potential for =
a
highly effective reducing atmosphere. I know that some people who fire with =
wood
are now injecting water into the airstream. Given the potential high flame
temperature of burning hydrogen perhaps this style of firing should be
investigated further.
Always looking for things to torment my simple mind.
Ivor. In South Oz, where we now have a studio with a concrete floor which is=
in
process of being sealed.
Gavin Stairs on sat 2 oct 99
At 03:12 PM 10/1/99 -0400, Ivor Lewis wrote:
...
>Gavin Stairs seems to be having some trouble with those long words. Must say I
>was fascinated with "monotonically descending curve like an exponential".
Hi Ivor,
I only do it to annoy, ...
Monotonically means only in one direction, at least that's what it means in
this context. In other words, it doesn't go down and up and down again:
just down. Not the same as a monotone in music, for example. Every
discipline uses the same words, only they make them mean something
different. Shades of Lewis Carrol: here we go with Alice, through the
looking glass.
And while an asymptote is what we are looking for, I described it
methodologically, not formally. I alluded to the many problems that can
occur, but didn't describe them. Too complicated. (Has anyone read Salman
Rushdie's wonderful book, Haroun and the Sea of Stories? Here we have a
PTCTE (Process Too Complicated To Explain).) Suffice to say that each
mechanism for binding water in the sample contributes a separate drying curve.
>One notion which has not been mentioned, or so it would seem unless I have
>missed something, is the additional calorific value of wet wood due to the
>Water
>Gas reaction. Above about 1100Celsius, superheated steam reacts freely with
>carbon to give free hydrogen and carbon monoxide. So wet gas striking those
>white hot coals in the fire box can give free combustible gas which promotes
>increasing temperature as it burns with secondary air and the potential for a
>highly effective reducing atmosphere. I know that some people who fire with
>wood
>are now injecting water into the airstream. Given the potential high flame
>temperature of burning hydrogen perhaps this style of firing should be
>investigated further.
In the presence of an iron catalyst, this used to be an important method
for producing commercial lighting gas (producer gas, water gas, town gas).
A similar reaction is used in the oxy-hydrogen plasma torch to transport
intense heat to the flame tip: an arc buried in the torch dissociates the
fuel and oxidizer, respectively H2 and O2, which are transported as a
plasma a few millimeters to the flame front, where they condense into water
(steam) by the cooling of the work piece. This results in a very intense
heat source being applied to a very small spot on the work piece, and
temperatures soar. Nowadays, the same work is usually done by lasers.
This process may contribute some to transporting of heat through the kiln,
but it does not add more energy. The energy made available by the gas is
already taken up by the dissociation reaction, so you still have to add the
heat from another source (i.e., the wood). I don't know how much this
reaction takes place in an ordinary fire. There is a good deal of mixing
up of reagents in a flame, and some water will undoubtedly be dissociated
and recombined, but whether much of it survives the flame front to
contribute importantly to any downstream process I doubt. But see the
comments below.
In addition (or subtraction), you have to supply the heat to evaporate the
water, so the net heat gain is negative. The steam you make transports
latent (unsensible) heat out of the kiln, and deposits in the nice, puffy,
white clouds coming out of your stack. So the temperature in the kiln goes
down, while the temperature outside the kiln goes up.
Water injected into a burner cools the flame. So enough water in the
system can change the way the fuel burns. This may produce less
undesireable kiln effluent, like NOx and dioxins, since there is less flame
energy density to produce them. It may also delay combustion of some
fractions, extending the flame. In the extreme, this might produce soot,
but I doubt that would be a problem in the later stages of firing a
ceramics kiln. In the early stage, yes: lots of smoke, not so much flame.
Steam itself is a catalyst of many reactions, and undoubtedly has a fluxing
action. So the presence of steam in the kiln probably promotes some
melting reactions, and may alter the fluidity, surface tension, etc, of a
glaze. In this context, it is worth noting that all hydrocarbon and
carbohydrate (e.g., cellulose) flames produce lots of water as one of their
major combustion products. So no fuel fired kiln is without a good deal of
water. The transport of this water in the refractory liner can contribute
to various problems there.
What does all this boil down to? Injected water, whether from wet wood or
from a hose, may alter the behavior of some glazes, etc., but it will not
make it easier to reach temperature. If you do reach temperature with wet
wood, you may see some differences from a dry wood firing.
Anyway, that's more than I set out to say in my original comment, so I hope
you're satisfied.
Gavin
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