Sam Yancy on tue 11 feb 03
Dear Clay buds.
I have a question. I am using several brands of clay - all rated cone five, and laguna glazes - cone 5 (many colors ). When checking the kiln (electric) after firing, using some glazes, they seem to be a bit "grainy" - while other glazes seem to run a bit ( I know which ones that do that so I am careful with the footers).
My question is this - I would like to to fire my rated Cone 5 CLAY to Cone 6 to see if I can reduce the "graininess" for some laguna glazes to improve the appearance of the pottery.
Your opinion please - is this workable - or will I "melt-down" the CLAY bodies and make a mess (I have seen what happens when you use cone 5 clay in a cone 10 kiln). I will run tests for sure - but your experience/opinion will be much appreciated.
P.S. The kiln is firing accurately. Thank you for your help in advance. Sam in Daly City CA.
Lorraine Pierce on wed 12 feb 03
Hi Sam, it sounds like a glaze mixing and application problem to me.
A grainy look is usually created when the glaze application is too thin.
Are the glazes you use dry commercial powders that you mix with water or
purchase wet in jars? How do you apply the glaze? Dipping, brushing or
spraying? The current thread on glaze thickness is a good one. It should be
of help. And don't forget, many glazes need that soak to become lush and
beautiful. Lori Pierce in New Port Richey, Fl.
----- Original Message -----
From: "Sam Yancy"
To:
Sent: Tuesday, February 11, 2003 9:57 PM
Subject: Cone temp question
> Dear Clay buds.
>
> I have a question. I am using several brands of clay - all rated cone
five, and laguna glazes - cone 5 (many colors ). When checking the kiln
(electric) after firing, using some glazes, they seem to be a bit
"grainy" - while other glazes seem to run a bit ( I know which ones that do
that so I am careful with the footers).
>
> My question is this - I would like to to fire my rated Cone 5 CLAY to
Cone 6 to see if I can reduce the "graininess" for some laguna glazes to
improve the appearance of the pottery.
>
> Your opinion please - is this workable - or will I "melt-down" the CLAY
bodies and make a mess (I have seen what happens when you use cone 5 clay
in a cone 10 kiln). I will run tests for sure - but your experience/opinion
will be much appreciated.
>
> P.S. The kiln is firing accurately. Thank you for your help in advance.
Sam in Daly City CA.
>
>
____________________________________________________________________________
__
> Send postings to clayart@lsv.ceramics.org
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Lois Ruben Aronow on wed 12 feb 03
Are you using dry glazes to which you add water? It sounds like a
mixing problem to me. I have had graininess when I forgot or
neglected to sieve the glaze.
Try running it through a sieve and applying it a tad thicker and see
what happens.
--------------------------------------------
=46ine Craft Porcelain - New and Updated for 2003!!
http://www.loisaronow.com=20
Sam Yancy on wed 12 feb 03
In reply - I am using dry glazes and mixing them with water and cmc/bentonite as needed. Also are straining them. Also sometimes spray (wet) or brush. Don't dip much. Reason for asking - is that a couple of years ago, I bought 27 laguna glazes in ten-twentyfive pound bags - dry - to save money. Most work but some are "grainey". I think that the cause is perhaps firing at cone 5 (some glazes) is too low - thinking about trying cone 6. Only worried about cone 5 clay "melt-down" in the kiln for these clay-bodies. Thank you for your advise. Sam in Daly City.
Lois Ruben Aronow wrote:Are you using dry glazes to which you add water? It sounds like a
mixing problem to me. I have had graininess when I forgot or
neglected to sieve the glaze.
Try running it through a sieve and applying it a tad thicker and see
what happens.
--------------------------------------------
Fine Craft Porcelain - New and Updated for 2003!!
http://www.loisaronow.com
______________________________________________________________________________
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.
Snail Scott on wed 12 feb 03
At 06:57 PM 2/11/03 -0800, you wrote:
>I would like to to fire my rated Cone 5 CLAY to Cone 6...is this workable
- or will I "melt-down"...
It might warp, but one cone more won't turn it into a
mess. It might be just fine, even. Many clays referred
to by a particular standard cone aren't, really. It
just makes marketing more convenient to group them that
way in the catalog. If you want to test the limits of
any unknown clay, though, just make a test bar with a
10 cm shrinkage mark, and fire it on top of a slab of
a sufficiently high-fire clay. Even if it melts, it
won't mess up your shelves. But, odds are that your
^5 clay will handle ^6 OK.
-Snail
Charles Moore on wed 12 feb 03
Sam,
I have tried a number of Laguna ^5 clays and have always fired to ^6 without
a problem.
I would note that our West Coast lists Western and Eastern clays; I am not
familiar with Eastern clays.
Charles
Sacramento
----- Original Message -----
From: "Sam Yancy"
To:
Sent: Tuesday, February 11, 2003 6:57 PM
Subject: Cone temp question
> Dear Clay buds.
>
> I have a question. I am using several brands of clay - all rated cone
five, and laguna glazes - cone 5 (many colors ). When checking the kiln
(electric) after firing, using some glazes, they seem to be a bit
"grainy" - while other glazes seem to run a bit ( I know which ones that do
that so I am careful with the footers).
>
> My question is this - I would like to to fire my rated Cone 5 CLAY to
Cone 6 to see if I can reduce the "graininess" for some laguna glazes to
improve the appearance of the pottery.
>
> Your opinion please - is this workable - or will I "melt-down" the CLAY
bodies and make a mess (I have seen what happens when you use cone 5 clay
in a cone 10 kiln). I will run tests for sure - but your experience/opinion
will be much appreciated.
>
> P.S. The kiln is firing accurately. Thank you for your help in advance.
Sam in Daly City CA.
>
>
____________________________________________________________________________
__
> 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.
Lois Ruben Aronow on wed 12 feb 03
On Wed, 12 Feb 2003 09:50:17 -0800 (PST), you wrote:
>
>In reply - I am using dry glazes and mixing them with water and =
cmc/bentonite as needed. Also are straining them.
Are you sieving, or just passing it through a strainer? A kitchen
strainer won't do - you need a sieve that's at least 60 mesh, but
preferably 80 mesh.
Also, if you are brushing, there are smoothing additives you should
use to even out the application of the glaze.
--------------------------------------------
=46ine Craft Porcelain - New and Updated for 2003!!
http://www.loisaronow.com=20
Belinda Willis on thu 13 feb 03
Sam,
Last summer, I got a new L&L, zone control, computerized kiln, went top of
the line and got protective thermocouple covers and all. After doing the
proper initial empty kiln firing, I filled the kiln and set the computer
using the pre-programmed cone 6 firing schedule which has a top temp of
2199 F. Was using Ron&John's glossie glazes so didn't need the cool down
schedule and was using Laguna's half and half cone 5 clay.
Just as the cone 5 witness cone was starting to bend, there was a medical
emergency in the house and by the time I got back from the emergency room,
the kiln had shut itself off. The cone 7 witness cone melted as flat as
the cone 5. Fired at least to cone 8, probably higher.
The cone 5 clay bloated like crazy but held its shape and I throw thin.
NONE of the glazes melted off the pots, in fact none of them even moved
significantly. If the clay had not had such a broad range and the glazes
had not been so incredibly forgiving, I would have had to throw out all my
shelves 'cause they never would have cleaned up. I gave thanks to the
pottery gods, Laugna and Ron&John but not necessarily in that order.
Turns out, L&L has since found, the high quality thermocouple covers are
insulating the thermocouples and the kilns with them are all firing one and
sometimes two cones too high. I now program the computer to fire to cone 6
using a top temp of 2145.
While I understand its not good to have a clay with too broad a firing
range, my deepest gratitudes go to Laguna.
Belinda Willis
Santa Rosa, CA
Ron Roy on fri 14 feb 03
Hi Sam,
Best thing is to test your clays to find out what the absorbency is at the
cone you want to fire at - it's not hard - let me know if you need
instructions.
It is not hard to slow down running in glazes - just a matter of adding
some clay.
RR
>I have a question. I am using several brands of clay - all rated cone
>five, and laguna glazes - cone 5 (many colors ). When checking the kiln
>(electric) after firing, using some glazes, they seem to be a bit
>"grainy" - while other glazes seem to run a bit ( I know which ones that
>do that so I am careful with the footers).
>
>My question is this - I would like to to fire my rated Cone 5 CLAY to
>Cone 6 to see if I can reduce the "graininess" for some laguna glazes to
>improve the appearance of the pottery.
>
>Your opinion please - is this workable - or will I "melt-down" the CLAY
>bodies and make a mess (I have seen what happens when you use cone 5 clay
>in a cone 10 kiln). I will run tests for sure - but your
>experience/opinion will be much appreciated.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Jon Pacini on fri 14 feb 03
"While I understand its not good to have a clay with too broad a firing
range, my deepest gratitudes go to Laguna."
Belinda Willis
Santa Rosa, CA
Greetings All and Belinda----Thank you very much for the Kudos. We do our
best.
Jon Pacini
Clay Manager
Laguna Clay Co
Ron Roy on sun 16 feb 03
Hi Belinda,
Thanks for posting this - good information for everyone.
First of all - never leave a kiln alone when it's at the end of it's cycle
- especially when it's the first firing - I know you know this - but for
anyone else firing a kiln for the first time - stay with it and watch the
cones - well before you think they are supposed to drop - you are trying to
calibrate your thermocouple to the cone your want to fire to - every
thermocouple reads temperature at least a little differently - some times
quite a bit.
I know I'm not being very gratious here but I do think your thanks to the
kiln gods is misplaced - they had nothing to do with either the cause of
the over firing or the results.
RR
>Last summer, I got a new L&L, zone control, computerized kiln, went top of
>the line and got protective thermocouple covers and all. After doing the
>proper initial empty kiln firing, I filled the kiln and set the computer
>using the pre-programmed cone 6 firing schedule which has a top temp of
>2199 F. Was using Ron&John's glossie glazes so didn't need the cool down
>schedule and was using Laguna's half and half cone 5 clay.
>
>Just as the cone 5 witness cone was starting to bend, there was a medical
>emergency in the house and by the time I got back from the emergency room,
>the kiln had shut itself off. The cone 7 witness cone melted as flat as
>the cone 5. Fired at least to cone 8, probably higher.
>
>The cone 5 clay bloated like crazy but held its shape and I throw thin.
>NONE of the glazes melted off the pots, in fact none of them even moved
>significantly. If the clay had not had such a broad range and the glazes
>had not been so incredibly forgiving, I would have had to throw out all my
>shelves 'cause they never would have cleaned up. I gave thanks to the
>pottery gods, Laugna and Ron&John but not necessarily in that order.
>
>Turns out, L&L has since found, the high quality thermocouple covers are
>insulating the thermocouples and the kilns with them are all firing one and
>sometimes two cones too high. I now program the computer to fire to cone 6
>using a top temp of 2145.
>
>While I understand its not good to have a clay with too broad a firing
>range, my deepest gratitudes go to Laguna.
>
>Belinda Willis
>Santa Rosa, CA
>
>______________________________________________________________________________
>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.
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
Belinda Willis on mon 17 feb 03
Ron Roy wrote:
I know I'm not being very gratious here but I do think your thanks to the
kiln gods is misplaced - they had nothing to do with either the cause of
the over firing or the results
You made me laugh.
Actually my thanks went to the kiln gods for the fact that I did not have
to throw out a whole kiln full of brand new shelves.
As you suggested, I had been babying that kiln, checking the cones every 15
minutes for over an hour, watching SOOO closely so I would be able to
record the temp when cone 6 was right on the mark. Then JUST as cone 5 was
starting to bend, my husband had a serious accident, I had to call 911 and
rush to the hospital. The next day when I opened the kiln and saw the cone
7 witness cone melted into a puddle, I would have given thanks to the
Dominoes Pizza man if I'd thought he'd played some small part in preserving
my brand new kiln.
Even more than the kiln gods, I gave silent thanks to the authors of the
Mastering Cone 6 Glazes book. Those glazes are incredible! Some of the
colors were muddy but the glazes had not turned to liquid pools around the
pots even at cone 8, or 9 or 10 or whatever cone the kiln had ultimately
fired to. I was SO grateful! I'm glad to have this opportunity to thank
you and John.
You are my heros.
Belinda
P.S. In your opinion, when IS it appropriate to thank the kiln gods?
Ron Roy on thu 20 feb 03
Hi Belinda,
Something more to be said for balanced glazes - enough silica and alumina
and the range of melting is extended.
When things go right it's my fault - when things go wrong I blame the gods
- if they aren't there to look after us then what good are they?
RR
>Even more than the kiln gods, I gave silent thanks to the authors of the
>Mastering Cone 6 Glazes book. Those glazes are incredible! Some of the
>colors were muddy but the glazes had not turned to liquid pools around the
>pots even at cone 8, or 9 or 10 or whatever cone the kiln had ultimately
>fired to. I was SO grateful! I'm glad to have this opportunity to thank
>you and John.
>
>You are my heros.
>
>Belinda
>
>P.S. In your opinion, when IS it appropriate to thank the kiln gods?
Ron Roy
RR#4
15084 Little Lake Road
Brighton, Ontario
Canada
K0K 1H0
Phone: 613-475-9544
Fax: 613-475-3513
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