Jump to content


Photo

What Happened?


  • Please log in to reply
8 replies to this topic

#1 Babs

Babs

    Advanced Member

  • Members
  • PipPipPip
  • 1,156 posts

Posted 01 November 2013 - 09:46 PM

Relatively recently I was firing  to C6 when an element was ruined by some glaze dropping onto it, flaking glaze syndrome, however as I was on a tight schedule and with optimism unfounded, I continued to fire, thinking that at some time before the exhibition this kiln would reach the temp. required. I fired for a night and a day and a night, old kiln, no computer controls, remember them??, and then tired and with temp at 1070 Celsius, I turned it off.

Rang hte other people in ex. to relate that my work would be quite diminished in number..  Isolated, new element some days/weeks away.

Opened the kiln to beautifully matured glazes!

I remember reading an article "Guan but not forgotten" where the potter related that he was firing stoneware glazes at around C6

What is going on, Heatwork?

Should I try to repeat this??  



#2 Biglou13

Biglou13

    Advanced beginner pottery, Advanced in other art

  • Members
  • PipPipPip
  • 1,071 posts
  • LocationNorth Florida

Posted 02 November 2013 - 03:45 AM

C6 is 1185 Celsius (ish)

My vote is for heat work.

I've been studying bizen pottery ......long firing cycles. Lower temps yet higher temp maturity. So yes it is highly probable heat work is maturing you glazes and clay.

Did you have any witness cones in firing? Is your clay also maturing/vitrifying?

Some times you get extraordinary responses from unusual situations.

My 2 cent vote is for yes try and repeat it.
And fix flaky glaze.
Caution big brother is watching.
The beige is blinding!!!!!!
The middle of the road is boring

The true sign of intelligence is not knowledge but imagination.
-Albert Einstein

#3 JBaymore

JBaymore

    Moderator

  • Moderators
  • 3,059 posts
  • LocationWilton, NH USA

Posted 02 November 2013 - 10:19 AM

Ceramic materials react to a combination of the application of heat energy over a certain amount of time.  Cones measure this combination at the location of the cone.  Pyrometers only measure instataneous temperature at the location of the probe.  The impact of the time and heat energy factor at the elevated end of the cycle is the significant part of this equation, so your described scenario is perfect for showing this impact.

 

So your results are likely the impact of the heatwork as biglou says. 

 

But there may be other factors at work here also.  You are saying "beautifully matured glazes".  Like most studio potters I am assuming that you are saying this simply because "they look good" when you opened the kiln.  I'm also going to bet that maybe you have never stopped a kiln firing of these particular glazes a bit short of your desired end point in the past.  I wonder if you had done so.... if they would not visually look about the same as what you saw here.  Maybe the glazes have a bit wider range than you think they do for a certain visual effect.

 

best,

 

.....................john


John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#4 Marcia Selsor

Marcia Selsor

    Professor Emerita, Montana State University-Billings

  • Members
  • PipPipPip
  • 4,130 posts
  • Locationwhere Texas, Matamoros, Rio Grande and Gulf of Mexico come together.

Posted 02 November 2013 - 10:50 AM

Must be good Karma and the Kiln Gods are with you.
Marcia

#5 neilestrick

neilestrick

    Neil Estrick

  • Members
  • PipPipPip
  • 2,835 posts
  • LocationGrayslake, IL

Posted 02 November 2013 - 12:19 PM

I would not try to repeat it again. You're wasting a ton of electricity firing that long. Chances are the heat work was in your favor, but it's an awful long time to fire to get to cone 6. If you did in fact reach cone 6 (which I don't think you did since the sitter (assuming there is one on the kiln) didn't shut off the kiln), reaching it slowly probably helped your glazes look better. The best way to mimic that in a much less wasteful manner is to fire to cone 4 and hold temp until cone 6 is reached. However that's incredibly difficult to do with a manual kiln.


Neil Estrick
Kiln Repair Tech
L&L Kilns Distributor
Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

neil@neilestrickgallery.com


#6 Babs

Babs

    Advanced Member

  • Members
  • PipPipPip
  • 1,156 posts

Posted 02 November 2013 - 05:58 PM

Thanks everyone.

I glaze fire to c03 and c5/6

I have placed a pot with the above mentioned glaze in the lower firing by mistake and did not get this result ie dull unfinished look.

Yes I did write beautiful... my relief at having soome pots was in that subjective description!

The cost factor would not allow me to repeat this with this glaze but, if say, I did this with a C9/10 glaze and as John adviced slow down thelast part of the firing then I would be tempted, had a couple of glazes from that range in the past which I would like to still go to.

Never got to C6 , 1080Deg Celsius top temp but don't know cone   C6 in sitter. still doing its thing.  going up 10 degs an hour for a lifetime it felt.

Yes the gods were with me or at least pitied my bleary state.



#7 JBaymore

JBaymore

    Moderator

  • Moderators
  • 3,059 posts
  • LocationWilton, NH USA

Posted 02 November 2013 - 08:44 PM

I have placed a pot with the above mentioned glaze in the lower firing by mistake and did not get this result ie dull unfinished look.

At cone 03 you would never see such close maturity.... but if you stopped at maybe cone 4 or 5 ...... you might see the results you saw.

 

best,

 

.....................john


John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#8 Babs

Babs

    Advanced Member

  • Members
  • PipPipPip
  • 1,156 posts

Posted 03 November 2013 - 04:00 PM

Thanks for the clarity John.

Have a few cool spots where I place wider fired glazed ware. My onglaze brush marks really do not integrate in to the glaze in these spots and the glaze looks a bit stiff so i figure that this glaze needs the C6 temp. in my long firing ordeal there were pots whose glaze did not make it, and so were refired.

What do you think would happen to my mid range clay if I were to subject it to the long firing needed to mature a C9 glaze?



#9 neilestrick

neilestrick

    Neil Estrick

  • Members
  • PipPipPip
  • 2,835 posts
  • LocationGrayslake, IL

Posted 05 November 2013 - 04:10 PM

What do you think would happen to my mid range clay if I were to subject it to the long firing needed to mature a C9 glaze?

 

Cone 9 is cone 9, no matter how you got there. Your cone 6 clay would be over fired, and likely slump or bloat or both.


Neil Estrick
Kiln Repair Tech
L&L Kilns Distributor
Owner, Neil Estrick Gallery, LLC
www.neilestrickgallery.com

neil@neilestrickgallery.com





0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users