David Hendley on thu 14 dec 00
I would suggest that wood has much more water in it
than gas. I have no idea if this is really the case, but it
seems right to me.
Even thin boards that have dried for a year in the Texas heat
often ooze sap out the cold end when thrown on my kiln grate.
Steam is always rising from burning boards.
Even 'kiln dried' lumber has, I think, about 15% moisture.
My best firings are on rainy days, when the air is 'heavy'.
It could also have to do with pressure, but I think moisture
improves the firing.
Speaking of dropping dumb things in your kiln, plastic coke
bottles, with the lids screwed on tight, are exciting.
A big pop, and sometimes some propulsion.
This week, while firing, I found some old batteries that
didn't make it to the trash.
I remembered that batteries always had written on them,
'Do not dispose of in fire. May cause explosion.'
Oh, boy, I thought, this could be fun.
To my disappointment, nothing happened.
I'm a professional on a closed track. Do not try this at home.
--
David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com/
----- Original Message -----
From: mel jacobson
To:
Sent: Thursday, December 14, 2000 4:11 PM
Subject: water in your kiln
| it is a very old trick, goes back to anctient china....woodfiring
| potters use it all the time...gallons.
|
| but, gas has a great deal of water in it already, and according
| to experts...almost redundant to add more.
| mel
| just be careful...steam backspray can take out an eye.
| a japanese potter used a filled balloon to drop in his
| anagama....blew back like a bomb...almost killed him.
| just like a bb gun...`hey, wally, your gonna shoot out your eye.`
|
mel jacobson on thu 14 dec 00
it is a very old trick, goes back to anctient china....woodfiring
potters use it all the time...gallons.
but, gas has a great deal of water in it already, and according
to experts...almost redundant to add more.
mel
just be careful...steam backspray can take out an eye.
a japanese potter used a filled balloon to drop in his
anagama....blew back like a bomb...almost killed him.
just like a bb gun...`hey, wally, your gonna shoot out your eye.`
FROM MINNETONKA, MINNESOTA, USA
http://www.pclink.com/melpots (website)
Hank Murrow on thu 14 dec 00
>it is a very old trick, goes back to anctient china....woodfiring
>potters use it all the time...gallons.
>
>but, gas has a great deal of water in it already, and according
>to experts...almost redundant to add more.
>mel
Dear Mel;
Some water vapor, whether from natural gas or from addition will contribute
to reduction. There was a nice booklet from Ohio State University about
"water vapor and the atmosphere" that I sent to Joe Molinaro. I wonder if
he'll weigh in on this one? It is my understanding that propane has much
less water vapor than natural gas, so there may be a benefit in slow drip
into the firebox in a propane-fired kiln.
Cheers, Hank in Eugene
Gail Nichols on fri 15 dec 00
Water in kilns is indeed an interesting topic, and not one that should be
limited to wood firers. There's plenty of scope for exploring its potential
in a gas kiln. Here's my two cents worth for the discussion.
Water can certainly cause a reduction effect; on the other hand, it will
also tend to clear out carbon. So it can be responsible for a range of
colour & textural effects. It's all related to what's called the 'water gas
reaction', used in gasification of coal. The following 2 reactions are
involved---water reacting with carbon fuel to produce carbon monoxide or
carbon dioxide, and hydrogen. Higher temperatures will favour the first
equation:
C + H2O + energy --> CO + H2
C + 2 H2O + energy --> CO2 + 2H2
In an electric kiln with no carbon fuel, I don't see how these equations
would apply.
By all means, one needs to be aware of potential problems with water
introduction, and exercise some caution and common sense---the water balloon
idea definitely sounds like one to avoid! On the other hand, consider the
amount of water that gets sprayed into soda kilns as common practice.
Personally, I find the atmospheric effects that occur when water seeps into
the kiln through the brickwork are usually nicer than when it's sprayed in.
I'd like to hear about other people's experiences with this.
Gail Nichols
Sydney, Australia
gailnichols@optusnet.com.au
----- Original Message -----
From: Hank Murrow
To:
Sent: Friday, December 15, 2000 1:01 PM
Subject: Re: water in your kiln
> >it is a very old trick, goes back to anctient china....woodfiring
> >potters use it all the time...gallons.
> >
> >but, gas has a great deal of water in it already, and according
> >to experts...almost redundant to add more.
> >mel
>
> Dear Mel;
>
> Some water vapor, whether from natural gas or from addition will
contribute
> to reduction. There was a nice booklet from Ohio State University about
> "water vapor and the atmosphere" that I sent to Joe Molinaro. I wonder if
> he'll weigh in on this one? It is my understanding that propane has much
> less water vapor than natural gas, so there may be a benefit in slow drip
> into the firebox in a propane-fired kiln.
>
> Cheers, Hank in Eugene
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
>
Marcia Selsor on fri 15 dec 00
Dear David,
I always thought firing a gas kiln on rainy days made the firing better
and easy to keep even. We don't get many rainy days in Montana but it is
true about the rain.
I thought it was the low barometric pressure (?).
Marcia
too bad about the batteries. could have been a spud gun affect.
David Hendley wrote:
>
snip
> My best firings are on rainy days, when the air is 'heavy'.
> It could also have to do with pressure, but I think moisture
> improves the firing.
>
> Speaking of dropping dumb things in your kiln, plastic coke
> bottles, with the lids screwed on tight, are exciting.
> A big pop, and sometimes some propulsion.
> This week, while firing, I found some old batteries that
> didn't make it to the trash.
> I remembered that batteries always had written on them,
> 'Do not dispose of in fire. May cause explosion.'
> Oh, boy, I thought, this could be fun.
> To my disappointment, nothing happened.
> I'm a professional on a closed track. Do not try this at home.
> --
> David Hendley
> Maydelle, Texas
> hendley@tyler.net
> http://www.farmpots.com/
>
> ----- Original Message -----
> From: mel jacobson
> To:
> Sent: Thursday, December 14, 2000 4:11 PM
> Subject: water in your kiln
>
> | it is a very old trick, goes back to anctient china....woodfiring
> | potters use it all the time...gallons.
> |
> | but, gas has a great deal of water in it already, and according
> | to experts...almost redundant to add more.
> | mel
> | just be careful...steam backspray can take out an eye.
> | a japanese potter used a filled balloon to drop in his
> | anagama....blew back like a bomb...almost killed him.
> | just like a bb gun...`hey, wally, your gonna shoot out your eye.`
> |
>
> ______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at melpots@pclink.com.
--
Marcia Selsor
selsor@imt.net
http://www.imt.net/~mjbmls
http://www.imt.net/~mjbmls/Tuscany2001.html
Martin Howard on fri 15 dec 00
So, some potters spray water into the kiln. Others use gas which has a high
proportion of water in it already.
I was taught, as were many others, to always leave the kiln top or/and spyes
open if there was any raw clay ware in the kiln to allow the water which
will be expelled from the clay to escape.
So, I waste some electricity by leaving the top open. Most of my ware is raw
as I am largely single firing.
But leaving the top open is not logical in the light of this information. I
could save some more energy units by keeping the kiln closed, always.
Have I missed something, friends?
Martin Howard
Webb's Cottage Pottery
Woolpits Road, Great Saling
BRAINTREE, Essex CM7 5DZ
England
martin@webbscottage.co.uk
RJones7582@AOL.COM on mon 18 dec 00
My buddy Roger and I decided that we would introduce water into our small
wood fired kiln by using approximately one piece of green wood to 3 or 4 of
dry wood. The firings have been better and the colors of the pieces better.
This way I can tell you is perfectly safe.
Bob Jones
David Hendley on wed 20 dec 00
Bob, using some green wood in a kiln is a good idea that
also works for me.
A couple of years ago, I switched from using slats
of wood from a mill, dried at my place for 6 months,
to broken-up old pallets.
The old pallet wood was so dry, from years of sitting
in warehouses, that the quality of my firings declined
and the kiln fired too fast.
So now, I use 'mostly dry wood', or, if I'm using old boards
I mix in some green wood to slow down the extra dry stuff.
--
David Hendley
Maydelle, Texas
hendley@tyler.net
http://www.farmpots.com/
----- Original Message -----
From:
To:
Sent: Monday, December 18, 2000 8:11 PM
Subject: Re: water in your kiln
| My buddy Roger and I decided that we would introduce water into our small
| wood fired kiln by using approximately one piece of green wood to 3 or 4
of
| dry wood. The firings have been better and the colors of the pieces
better.
| This way I can tell you is perfectly safe.
|
| Bob Jones
|
| |
|
