John Baisch on mon 5 aug 96
Hello All,
I pulled out the RAKU kiln this weekend and fired
some copper based glazes (Alligator, Rainbow peacock, etc.)
I must be having a mental block or something but every thing is
coming out copper penny color. I was able to get the gamit of colors
reds blues, greens a few weeks ago and in the past, but something
has changed and for the life of me I can't figure it out.
This is what I'm doing, I'm firing the pieces up to about
1800-1900F until the glaze is flowing. I pull the piece
immediately out and place it in small garbage can filled with
schredded paper. I let the paper catch on fire and
immediately close the lid. About 4-5 mins later pull out
the piece. I get nothing but dull copper color.
I can't grasp what I'm doing wrong, any insight would be
greatly appreciated.
Also, does anyone know where William Turner is?
Thanks,
JB
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~ John Baisch ~~~~~~~~~~~~~~~~~~~~~~~~
~~~~~~~~ E-Mail: jbaisch@micron.net ~~~~~~
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Jack Phillips on tue 6 aug 96
At 01:14 PM 8/5/96 EDT, you wrote:
>----------------------------Original message----------------------------
every thing is
>coming out copper penny color. I was able to get the gamit of colors
>reds blues, greens a few weeks ago and in the past, but something
>has changed and for the life of me I can't figure it out.
>
>Also, does anyone know where William Turner is?
>
>~~~~~~~~ E-Mail: jbaisch@micron.net ~~~~~~
>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
>
JB,
William Turner Lives in central Florida Around Tampa. His email address is:
As far as your colors go, there is at least 10 diferent variables I can name
off hand that will effect your ability to "generate" color on raku coppers.
You are on the right track though, you need to get a good copper before your
piece will develope colors. Put one of your "copper" vases in the oven on
400 to 425 degrees to see what I mean.
Jack Phillips
STONART Ceramic art
Portland, Oregon
Web site:
http://www.worldstar.com/~stonart/welcome.html
Jim Connell or set clayart mail on tue 6 aug 96
WINTHROP UNIVERSITY Electronic Mail Message
Date: 05-Aug-1996 05:11pm EDT
From: James Connell
CONNELLJ
Dept: Art and Design
Tel No: 323-2126
TO: SMTP%"CLAYART@lsv.uky.edu" ( _SMTP%"CLAYART@lsv.uky.edu" )
Subject: RE: That crazy RAKU
John,
If your copper based raku glazes are all turning out shiny or dull copper penny
you are obviously heavily reducing or over reducing or just getting too much
damm smoke. You are doing everything I do, but after a minute or so in the
smoking can, I "burb" the lid, giving it some air and reoxidizing part of the
glaze. Your timing of how long to open it will depend on a few things. If your
pots are thick they will retain the heat longer and you can open it for about
3-5 seconds. If you want more green, keep it open longer thus reoxidizing the
glaze. Thin pieces cool off so fast that it is very hard to get them in the can
fast enough to allow them to get enough smoke to work normally. I usually open
the can's lid and wait momentarily for the flame to explode and then quickly put
the lid back on. Be careful, the flame has the potential of really exploding as
the air rushes in. Even if you take the lid off and close it fast it still
could ignite and pop the lid off. You can tell how tight your seal is (can and
lid) once you put the lid back on because the flame will try to suck (if the
seal is tight) as much air as it can to keep burning. I have even opened up the
can and watched the pot change colors. Unfortunately, I don't recommend doing
this unless your are in to watching a glaze transmutate across it's spectrum.
By the time you see a color you like it will be to late to freeze it unless you
use a hose to cool it and I'm not sure if that will even work. I'm not into
force cooling my pots-too much damage can occur and since I refire my raku pots
as many times as it takes to get the color I want, I can't afford to have any
more sudden temperture changes (thermal shock) than necessary.
Newspaper is good and readily available. Fluff it up to get it to burn easily
and don't stuff your can full. I see no need to shread the newspaper, it will
just lie flat with no air in between to help it ignite. I loosely (very
loosely) wad up the newspaper and fill the can up half way. And depending on
how much reduction I want I may or may not throw more paper on top of the pot
before putting the lid on.
Raku is easy, too easy if you ask me. But it sells so damm well its hard to
stop making them. Besides I always wonder (worry) what my raku pots are going to
look like ten or twenty years down the road. Some one asked about the propane
torch trick. It too is easy-hit any copper based raku pot (preferably a copper
matt glaze) (after it has been fired) with the torch and watch the colors grow
(that gasoline on water rainbow iridescent look). However, stick around for a
couple of months and watch the colors disappear as it slowly reoxidizes. I
asked a fellow potter at an art fair what he does when a disgruntled customer
complains about his expensive once colorful raku pot that has since turned
brown. He says he offers to refire it-- for the life of the pot--what a drag.
My glaze has a lot of silica and flux in it and thus gives a good glassy melt
and as long as I reoxidize it some, my colors have been pretty constant but
they, occasionally, do get a little muddy with time.
Refire your pots and see what happens. There is a hugh group of the buying
public that will go gaga over the stuff. Years ago I was selling at the Ann
Arbor Street Fair (back when I was working exclusively with porcelain) and sat
for four day watching my next door neighbor wrap and sell and wrap and sell his
well made raku pots while I, Tom Turner and Tim Mather sat on our behinds
mumbling fowl things about raku. If you're wondering why I started doing raku,
I was "forced" into it when I moved to this job and only had electric kilns for
three years while my department went through a major renovation. Part of me was
happy to have the opportunity to learn a new process and shake things up. But
now that I have access to a gas kiln and have returned to high fire I still have
people demanding the raku stuff and its hard to turn down the green stuff. I
guess I feel a little guilty selling soft bisque ware when I was raised in the
hard, durable, vitreous ware tradition. I loved being able to say "...you can
put it in the microwave...the dishwasher...eat off it...has no lead...can bury
it for 2,000 years and it will be as good as new...etc.etc."
Jim
15 more days before the munchkins return to school!
Charles Williams on tue 6 aug 96
John,
It sounds like you might be firing in reduction in the kiln. I get the same
results with Del Favero Luster if I am not careful to fire in oxidation and
reduce post firing. I guess you know that any flame coming out the chimney is
a sign of incomplete combustion (reduction atmosphere) in the kiln. Also, a
yellow flame from the burner can result in the same effect. You might try
either reducing the gas flow into the kiln or use a blower of some sort to
force more air into the kiln.
Hope this helps!
Charles
Clyde Wynia on tue 6 aug 96
At 01:14 PM 8/5/96 EDT, you wrote:
>----------------------------Original message----------------------------
>
>Hello All,
>
>I pulled out the RAKU kiln this weekend and fired
>some copper based glazes (Alligator, Rainbow peacock, etc.)
>
>I must be having a mental block or something but every thing is
>coming out copper penny color. I was able to get the gamit of colors
>reds blues, greens a few weeks ago and in the past, but something
>has changed and for the life of me I can't figure it out.
>
>This is what I'm doing, I'm firing the pieces up to about
>1800-1900F until the glaze is flowing. I pull the piece
>immediately out and place it in small garbage can filled with
>schredded paper. I let the paper catch on fire and
>immediately close the lid. About 4-5 mins later pull out
>the piece. I get nothing but dull copper color.
>
>I can't grasp what I'm doing wrong, any insight would be
>greatly appreciated.
All the copper glazes will give the copper penny look unless oxygen is
re-introduced at the right temp (400 to 450 F). There was an excellent
article on this in CM in May of 94. If you don't have access to a copy I can
sent you a hard copy if you give your snail mail address. It is of great
help on getting the multi-colors from copper.
Clyde Wynia
M222 Sugarbush Lane,
Marshfield, WI 54449
Work 715-387-2580
Home 717-387-1653
Fax 715-387-1212
Ken Cowan on tue 6 aug 96
At 09:23 AM 8/6/96 EDT, you wrote:
>----------------------------Original message----------------------------
>John,
>
> You might try
>either reducing the gas flow into the kiln or use a blower of some sort to
>force more air into the kiln.
>
> Hope this helps!
>
> Charles
You can also tell if you kiln is firing in reduction by the bricks
turning grey or black. I fixed my raku kiln by enlarging the
flue opening. I think the principle is that more air rushes
out the kiln through the top, therefore more has to be pulled in
through the burners or around the burner ports.
Hope this helps.
KC
------------------------------------------------------
Ken Cowan Thomson Software Products
cowan@east.thomsoft.com 200 Wheeler Rd
Burlington, MA 01803
Jeremy/Bonnie Hellman on wed 7 aug 96
I don't have a lot of raku experience but I was advised by people who raku
fire a lot that copper pots should be sprayed with clear "paint". They said
to use the inexpensive spray cans of paint that come is a lot of colors -
only select the clear color. I know there have been other postings of how
to prevent oxidation of metallic raky glazes, but I'm hoping that the
advice I got is good, since that's what I did! Bonnie
>Subject: RE: That crazy RAKU
>
>John,
>
>If your copper based raku glazes are all turning out shiny or dull copper penny
>you are obviously heavily reducing or over reducing or just getting too much
>damm smoke. You are doing everything I do, but after a minute or so in the
>smoking can, I "burb" the lid, giving it some air and reoxidizing part of the
>glaze. Your timing of how long to open it will depend on a few things. If your
>pots are thick they will retain the heat longer and you can open it for about
>3-5 seconds. If you want more green, keep it open longer thus reoxidizing the
>glaze. Thin pieces cool off so fast that it is very hard to get them in the can
>fast enough to allow them to get enough smoke to work normally. I usually open
>the can's lid and wait momentarily for the flame to explode and then
>quickly put
>the lid back on. Be careful, the flame has the potential of really
>exploding as
>the air rushes in. Even if you take the lid off and close it fast it still
>could ignite and pop the lid off. You can tell how tight your seal is (can and
>lid) once you put the lid back on because the flame will try to suck (if the
>seal is tight) as much air as it can to keep burning. I have even opened
>up the
>can and watched the pot change colors. Unfortunately, I don't recommend doing
>this unless your are in to watching a glaze transmutate across it's spectrum.
>By the time you see a color you like it will be to late to freeze it
>unless you
>use a hose to cool it and I'm not sure if that will even work. I'm not into
>force cooling my pots-too much damage can occur and since I refire my
>raku pots
>as many times as it takes to get the color I want, I can't afford to have any
>more sudden temperture changes (thermal shock) than necessary.
>
>Newspaper is good and readily available. Fluff it up to get it to burn easily
>and don't stuff your can full. I see no need to shread the newspaper, it will
>just lie flat with no air in between to help it ignite. I loosely (very
>loosely) wad up the newspaper and fill the can up half way. And depending on
>how much reduction I want I may or may not throw more paper on top of the pot
>before putting the lid on.
>
>Raku is easy, too easy if you ask me. But it sells so damm well its hard to
>stop making them. Besides I always wonder (worry) what my raku pots are
>going to
>look like ten or twenty years down the road. Some one asked about the propane
>torch trick. It too is easy-hit any copper based raku pot (preferably a copper
>matt glaze) (after it has been fired) with the torch and watch the colors grow
>(that gasoline on water rainbow iridescent look). However, stick around for a
>couple of months and watch the colors disappear as it slowly reoxidizes. I
>asked a fellow potter at an art fair what he does when a disgruntled customer
>complains about his expensive once colorful raku pot that has since turned
>brown. He says he offers to refire it-- for the life of the pot--what a drag.
>My glaze has a lot of silica and flux in it and thus gives a good glassy melt
>and as long as I reoxidize it some, my colors have been pretty constant but
>they, occasionally, do get a little muddy with time.
>
>Refire your pots and see what happens. There is a hugh group of the buying
>public that will go gaga over the stuff. Years ago I was selling at the Ann
>Arbor Street Fair (back when I was working exclusively with porcelain) and sat
>for four day watching my next door neighbor wrap and sell and wrap and sell his
>well made raku pots while I, Tom Turner and Tim Mather sat on our behinds
>mumbling fowl things about raku. If you're wondering why I started doing raku,
>I was "forced" into it when I moved to this job and only had electric kilns for
>three years while my department went through a major renovation. Part of
>me was
>happy to have the opportunity to learn a new process and shake things up. But
>now that I have access to a gas kiln and have returned to high fire I
>still have
>people demanding the raku stuff and its hard to turn down the green stuff. I
>guess I feel a little guilty selling soft bisque ware when I was raised in the
>hard, durable, vitreous ware tradition. I loved being able to say "...you can
>put it in the microwave...the dishwasher...eat off it...has no lead...can bury
>it for 2,000 years and it will be as good as new...etc.etc."
>
>Jim
>
>15 more days before the munchkins return to school!
Autumn Downey on thu 8 aug 96
John,
You probably have a more accurate temperature reading when you raku than we
do - so this may not apply. (We eyeball it and whether the day is sunny or
cloudy does affect perception somewhat). But firing just a little cooler
does seem to get us back towards the blues and greens. Real copper we are
usually quite glad of, but the overfired version is pretty dull and kinda ugly.
Autumn Downey
downeya@internorth.com
Yellowknife, NWT, Canada
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