Understanding Pottery Chapter 17 Kiln Performance Problems

Welcome to Understanding Pottery, Chapter 17: Kiln Performance Problems.
There seem to be so many ways that bad things can happen to good pots. Defects in fired ceramics can originate with the clay, the glaze, as well as the actual firing process. This episode we’ll discuss problems with kiln operation and firing-related defects.
The next topic in the series is Defects in Fired Clay or Clay Defects.
Understanding Pottery is a series in production by Washington Street Studios. The video series is a digital textbook that will take you through the entire ceramic process from the raw material through the finished ceramic pieces. There are five sections and twenty-six chapters planned in the series and they are:
Section I: The Pottery Making Sequence
Chapter 1: What is Clay?
Chapter 2: Clay Properties and Drying
Chapter 3: Bisque Firing
Chapter 4: Tips for Successful Glazing
Chapter 5: Pyrometric Cones
Chapter 6: Glaze Firing
Section II: Use of Raw Materials
Chapter 7: Chemistry for Potters
Chapter 8: Glaze Chemistry
Chapter 9: Oxides, Washes, Underglazes and Stains
Chapter 10: Geology for Potters
Chapter 11: Use of Local Materials
Section III: Kilns and Firings
Chapter 12: Atmospheric Firings
Chapter 13: Wood-Fired Kilns
Chapter 14: Gas-Fired Kilns
Chapter 15: Electric Kilns
Chapter 16: Raku Kilns
Section IV: Solving Problems
Chapter 17: Kiln Performance Problems
Chapter 18: Clay Body Defects
Chapter 19: Glaze Defects
Section V: Practical Applications
Chapter 20: Pottery Myths, Errors and Misconceptions
Chapter 21: Thixotropy, Quartz Inversions and Other Pottery Mysteries
Chapter 22: Pottery and Physics
Chapter 23: Pottery Figurin’ (Math)
Chapter 24: Personal Safety with Pottery
Chapter 25: Critiquing Your Own Pottery: Design Principles You Can Use
Chapter 26: Tips for Buying Used Pottery Equipment
Show notes, including handouts, can be found at www.hfclay.com/the-potters-ro...
The Potters’ Round Table is brought to you by Washington Street Studios, a community pottery studio, gallery, and pottery school located in Harpers Ferry / Bolivar, WV. We exist to provide ceramic artists an affordable, fully equipped studio space for aspiring, emerging and established artists to share their creative energy and knowledge in an environment designed to support the ceramic artist. If you want to learn more about Washington Street Studios, visit our website at www.hfclay.com/.
At Washington Street Studios, we believe the sharing of creative energy and knowledge will improve the quality of our art and increase the appreciation of art within our community. We are striving to create an environment where the arts are shared and appreciated. We want to grow as a family of artists and contribute to our community. This podcast is one of our steps to share our passion for the ceramic arts, creative energy and knowledge with other artists and art lovers.
We also created an audio version to expand our audience. If you are looking for the podcast of our show search for the ‘The Potters Round Table’ on your podcast platform of choice.

[@nevenkamartinello]

As always, these videos are amazing! I have no words to describe how happy I am to have found this course!!!!!!!!!!! Have you ever thought about making a video on how to start a community workshop... for those who dream of creating it, but don't really know where to start...?

[@WashingtonStreetStudios]

I have actually, I'm just looking for the time to do it! All of this was easier when there were two of us running the business!

[@bandwilkalviwilk8437]

Thank you you answered my question in your introduction

[@WashingtonStreetStudios]

You are most welcome and we are glad you found this video of value! Please share it with your friends and fellow potters and help us grow our ceramic community!

[@ehaballithawy3711]

amazing

[@WashingtonStreetStudios]

Thank you

[@ehaballithawy3711]

these days i'm thinking to build my own gas kiln, so like your Lectures so much.

[@marlyswilliams9949]

On an electric kiln, what replacement schedule do you recommend for the elements? Per the manual for my kiln, elements are rated at 50-150 firings. With cone 10 firings, when do you recommend replacement of the elements? Thank you for a very informative series of lectures. Very appreciated and thank you.

[@WashingtonStreetStudios]

Marlys, Thank you for the question. Elements degrade over time and several factors contribute to the degradation. The hotter the kiln is fired shortens the life span of an electric kiln element. How well the kiln is vented plays a key role in getting the harmful fumes out of the kiln and a kiln vent is best. Vent hoods do not remove the fumes from the kiln. Keeping debris off the elements will increase the lifespan. At our studio we have two electric kilns, both of them L&L E Quad Pro production kilns which have twice the elements of normal kilns. One has already been fired over 150 times on the original elements and they are not yet showing signs of wear. Our firing times are within a variance of 1 minute, in fact closer to 30 seconds, from the original firing. We keep a spare set of elements so we don't have down time if one of the kiln fails. Long answer to say keep firing the kiln until it starts taking longer to fire than it should or until you have a kiln failure. And just have a spare set of elements around if you can. I hope this helps!

[@marlyswilliams9949]

@@WashingtonStreetStudios Many thanks for your response. I appreciate it. I do vacuum kiln interior. Also, run a “Bailey” kiln vent the entire firing, until the last 100 degrees. I had an early failure of the floor element after approx 16 firings in the new kiln. One of those situations that can happen, I guess. At 109 firings, no further element failures, yet. Have replaced thermocouples at firing 103. Great lecture series that I have just discovered. Best wishes from Wisconsin and thx again.

[@annaponomareva5749]

Thank you for the lectures about the electric kilns! After recent glaze firing I found some of the materials (I suspect it's copper oxide that was applied on some of the pots) from the pots eaten into the floor of the kiln. We didn't cover the floor of the kiln with kiln wash previously, so the oxide is deep in the floor bricks now. I'm rewatching these series hoping to find an answer on how to deal with this now. Is it good idea to sand it out as many potters suggest? Should we also coat the kiln floor with kiln wash next time? Appreciate if you can share some tips on this! Thanks!

[@WashingtonStreetStudios]

I've forwarded the question to Phil and will post his response. Thanks for watching!

[@WashingtonStreetStudios]

Hi Anna, Thanks for your email and your questions. First, it sounds like you don't have a kiln shelf at the bottom of your kiln? It's a REALLY good idea to have a shelf on 1/2" or 1" posts that you leave in the bottom of the kiln so that you're not putting pots right on the bricks at the bottom. Plus, the air space below the shelf provides insulation, or air circulation if you have a down-draft kiln vent. If you do install a bottom shelf, then don't worry about the holes in the bottom bricks. The copper oxide, or whatever it was that started to eat into the bricks, will stop eating after a while. If the looks of the holes bothers you, you could always fill them up with kiln cement or a 1:1 mixture of clay and fine sawdust (let it dry) before your next bisque firing. Phil

[@annaponomareva5749]

@@WashingtonStreetStudios Thank you for the advise! We normally put a kiln shelf at the bottom of the kiln on short posts, but it seems that the shelf is not wide enough to cover the bottom fully on the sides.. We ended up sanding the bottom bricks and covering them with kiln wash. Oxide didnt eat up too deep, so there are no holes afterwards:)

[@raymondjulius2479]

I guess I am kind of randomly asking but do anybody know of a good place to watch newly released tv shows online ?

[@timothyira5270]

@Raymond Julius Flixportal :D