Windancer Studio: Teresa Testa on thu 22 sep 05
I was very disappointed with my last firing. All of the glazes seemed washed out. I had a beautiful bright yellow that came out almost white, all the greens were almost white also. I use cone 10 porcelain and cone 10 glazes. Is it possible the glazes are too old. I think most were made in July, although some might be as old as April. I have not had trouble in the past using glazes that were a few months old.
Perhaps it was the kiln firing too hot??? I fired to 2345 F. I changed out the thermal couple just before I fired.
What temperature could I safely go down to and still use my cone 10 glazes?
Thanks for your help.
Teresa Testa
Windancer Studio
www.windancerstudio.com
Dave Finkelnburg on thu 22 sep 05
Teresa,
Your question is difficult to answer. IF you are firing strictly to a cone, you can fire to any temperature that allows you to achieve the particular cone deformation you want. IF you are firing to temperature and also a cone (a better approach according to recent research) you can pick a temperature that does not exceed the cone deformation you want, and then soak at that temperature until you get the desired bend to the cone.
Cone 10 can be put down over a wide temperature range. In my experience, in a fast fire a large cone 10 will stand 2,345°F, while in a slow firing it will bend fully at 2,260°F.
Age of glaze will not remove colorants like chrome or copper from your glaze, but temperature can cause those particular elements to vaporize and be lost, thus reducing the intensity of the glaze color.
If, through experience, you find your current firing temperature is too high, fire to a lower temperature and soak longer to get the cone down. Firing test tiles until you learn what will work best for you may reduce your frustrations and disappointments.
Good potting!
Dave Finkelnburg
"Windancer Studio: Teresa Testa" wrote:
I was very disappointed with my last firing. All of the glazes seemed washed out. I had a beautiful bright yellow that came out almost white, all the greens were almost white also. I use cone 10 porcelain and cone 10 glazes. Is it possible the glazes are too old. I think most were made in July, although some might be as old as April. I have not had trouble in the past using glazes that were a few months old.
Perhaps it was the kiln firing too hot??? I fired to 2345 F. I changed out the thermal couple just before I fired.
What temperature could I safely go down to and still use my cone 10 glazes?
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Edouard Bastarache Inc. on thu 22 sep 05
" Cone 10 can be put down over a wide temperature range. In my experience,
in a fast fire a large cone 10 will stand 2,345°F, while in a slow firing it
will bend fully at 2,260°F."
Cette situation nous ressemble :
1-En cuisson rapide cone 10 lui donne 2,345 F sur le thermocouple
2-En cuisson lente cone 10 lui donne 2,260 F
Donc la différence de 85 F, c'est moins que nous à 140 F mais ça
démontre la différence entre les 2 systèmes de mesure.
À plus tard,
Windancer Studio: Teresa Testa on fri 23 sep 05
Thank you for the information David. An off list reply from Steve Slatin s=
uggested that I calibrate my thermal couple. I don't know how to do this a=
nd honestly I didn't know you had to do it. How do you calibrate a thermal=
couple? I have a Bartlett controller model V6-CF. The kiln is a front lo=
ading 12 cu. ft. Crucible electric. The firing schedule I use is very long=
with a lot of soak time. This cone 10 firing took 23 hours. I have a slow=
rate of climb and some crystal hold time at the end.
I will try firing to a lower temurature with some test tiles. The problem=
is the kiln is so big I will have to fire short loads. I will also use co=
ne packs next time.
Thanks also to the many others who have replied with helpful information. =
Clayart is great!
Thanks, Teresa Testa
Windancer Studio
Teresa,
Your question is difficult to answer. IF you are firing strictly to =
a cone,
you can fire to any temperature that allows you to achieve the particular c=
one deformation
you want. IF you are firing to temperature and also a cone (a better appro=
ach according
to recent research) you can pick a temperature that does not exceed the con=
e deformation
you want, and then soak at that temperature until you get the desired bend =
to the
cone.
Cone 10 can be put down over a wide temperature range. In my experie=
nce,=20
in a fast fire a large cone 10 will stand 2,345=B0F, while in a slow firing=
it will
bend fully at 2,260=B0F.
Age of glaze will not remove colorants like chrome or copper from you=
r glaze,
but temperature can cause those particular elements to vaporize and be lost=
, thus
reducing the intensity of the glaze color.
If, through experience, you find your current firing temperature is t=
oo high,
fire to a lower temperature and soak longer to get the cone down. Firing t=
est tiles
until you learn what will work best for you may reduce your frustrations an=
d disappointments.
Good potting!
Dave Finkelnburg
"Windancer Studio: Teresa Testa"
wrote:
I was very disappointed with my last firing. All of the glazes seemed washe=
d out.
I had a beautiful bright yellow that came out almost white, all the greens =
were=20
almost white also. I use cone 10 porcelain and cone 10 glazes. Is it possib=
le the
glazes are too old. I think most were made in July, although some might be =
as old
as April. I have not had trouble in the past using glazes that were a few m=
onths
old.
Perhaps it was the kiln firing too hot??? I fired to 2345 F. I changed out =
the thermal
couple just before I fired.
What temperature could I safely go down to and still use my cone 10 glazes?
Donald Schnell Studio on fri 23 sep 05
If you have fired successfully that glaze before, changing the
thermocouple cause you to misfire. The aged thermocouple does not read
as accurately or as quickly so you will get a different firing.=20
You should learn what the effect of a new thermocouple on your work is
so that you can always compensate when you make the change. Similar to
if you only change one element in a kiln and the others are well-used.
Artistic Villas
by Deborah & Donald Schnell
http://www.artisticvillas.com
=20
800-253-7107
=20
Donald Schnell Studio, Inc.
http://www.donaldschnell.com
=20
Bougainvillea Leasing Ltd.
http://www.stjohncars.com
=20
=20
-----Original Message-----
From: Clayart [mailto:CLAYART@lsv.ceramics.org] On Behalf Of Dave
Finkelnburg
Sent: Thursday, September 22, 2005 5:33 PM
To: CLAYART@lsv.ceramics.org
Subject: Re: Washed out cone 10 glazes
Teresa,
Your question is difficult to answer. IF you are firing strictly
to a cone, you can fire to any temperature that allows you to achieve
the particular cone deformation you want. IF you are firing to
temperature and also a cone (a better approach according to recent
research) you can pick a temperature that does not exceed the cone
deformation you want, and then soak at that temperature until you get
the desired bend to the cone.
Cone 10 can be put down over a wide temperature range. In my
experience, in a fast fire a large cone 10 will stand 2,345=B0F, while =
in
a slow firing it will bend fully at 2,260=B0F.
Age of glaze will not remove colorants like chrome or copper from
your glaze, but temperature can cause those particular elements to
vaporize and be lost, thus reducing the intensity of the glaze color.
If, through experience, you find your current firing temperature
is too high, fire to a lower temperature and soak longer to get the cone
down. Firing test tiles until you learn what will work best for you may
reduce your frustrations and disappointments.
Good potting!
Dave Finkelnburg
"Windancer Studio: Teresa Testa" wrote:
I was very disappointed with my last firing. All of the glazes seemed
washed out. I had a beautiful bright yellow that came out almost white,
all the greens were almost white also. I use cone 10 porcelain and cone
10 glazes. Is it possible the glazes are too old. I think most were made
in July, although some might be as old as April. I have not had trouble
in the past using glazes that were a few months old.
Perhaps it was the kiln firing too hot??? I fired to 2345 F. I changed
out the thermal couple just before I fired.
What temperature could I safely go down to and still use my cone 10
glazes?
__________________________________________________
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Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
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