[Dharsi]

So I fired my kiln on Saturday for a ^10 glaze firing. If you remember I had asked about the kiln sitter in an earlier post. Well I adjusted the kiln sitter and after 8 hours the kiln sitter hadn't budged so I chickened out and pulled the plug. Everything was obviously under fired and my witness cones were standing tall. I checked my kiln sitter again, chatted up my old pottery instructor and gave it another go today. Well twelve hours in, again I pulled the plug. I couldn't see the cones even with sunglasses and blowing in with a straw to clear the atmosphere. Well after 20 minutes or so I pulled the peep again and I can see one cone standing. I wonder if they all are. I will know tomorrow. I guess I will spend some quality time on the phone with Skutt tomorrow and also hook up the pyrometer I had stuffed away in a drawer and finally found. I'm strongly considering three things:
1. Taking up golf instead
2. Switching to cone 6
3. Buying a new kiln
In the meantime I guess I'll take a nap.

[Chris Campbell]

In order to trust your kiln why don't you put in a cone 6 and a cone 7 and an 8 .... Then you will know something is happening and you'll stop pulling the plug! In my experience twelve hours is not overtime for a cone 10 firing.

[Arnold Howard]

Dharsi, on 17 April 2012 - 03:55 PM, said:

So I fired my kiln on Saturday for a ^10 glaze firing. If you remember I had asked about the kiln sitter in an earlier post. Well I adjusted the kiln sitter and after 8 hours the kiln sitter hadn't budged so I chickened out and pulled the plug. Everything was obviously under fired and my witness cones were standing tall. I checked my kiln sitter again, chatted up my old pottery instructor and gave it another go today. Well twelve hours in, again I pulled the plug. I couldn't see the cones even with sunglasses and blowing in with a straw to clear the atmosphere. Well after 20 minutes or so I pulled the peep again and I can see one cone standing. I wonder if they all are. I will know tomorrow. I guess I will spend some quality time on the phone with Skutt tomorrow and also hook up the pyrometer I had stuffed away in a drawer and finally found. I'm strongly considering three things:
1. Taking up golf instead
2. Switching to cone 6
3. Buying a new kiln
In the meantime I guess I'll take a nap.

I would fire to cone 6 instead of cone 10. Your kiln probably barely reached cone 10 after 12 hours. You don't need a new kiln.

Here is an article on viewing witness cones in an electric kiln. You should not have to blow air against the cones to see them even at cone 10.

http://www.paragonwe...ter.cfm?PID=291

Sincerely,

Arnold Howard
Paragon Industries, L.P., Mesquite, Texas USA
ahoward@paragonweb.com / www.paragonweb.com

[neilestrick]

Cone 10 is a lot of work for any electric kiln, unless you have one that's built for extra power. 12 hours is not too long by any means. Any time you use cones, you should always use warning cones to see the progress of the firing. If you're firing to cone 10, put in a 6 and 8 as well.

There's really very little reason to fire cone 10 in oxidation, besides some fancy crystalline glazes. Cone 10, in my opinion, is best reserved for reduction firings in fuel burning kilns. Cone 6 will increase your element life and reduce your electricity consumption a great deal.

[Dharsi]

neilestrick, on 17 April 2012 - 06:52 PM, said:

Cone 10 is a lot of work for any electric kiln, unless you have one that's built for extra power. 12 hours is not too long by any means. Any time you use cones, you should always use warning cones to see the progress of the firing. If you're firing to cone 10, put in a 6 and 8 as well.

There's really very little reason to fire cone 10 in oxidation, besides some fancy crystalline glazes. Cone 10, in my opinion, is best reserved for reduction firings in fuel burning kilns. Cone 6 will increase your element life and reduce your electricity consumption a great deal.

I hear you all. I've seen the light so to speak. For right now, I am lucky to have an electric kiln and gas is not in the picture so I will be switching over to ^6. Of course I hate not using all the great ^10 glazes I have I may have to stick with the 10 until I use it up and all the clay too!

[neilestrick]

Dharsi, on 17 April 2012 - 06:26 PM, said:

neilestrick, on 17 April 2012 - 06:52 PM, said:

Cone 10 is a lot of work for any electric kiln, unless you have one that's built for extra power. 12 hours is not too long by any means. Any time you use cones, you should always use warning cones to see the progress of the firing. If you're firing to cone 10, put in a 6 and 8 as well.

There's really very little reason to fire cone 10 in oxidation, besides some fancy crystalline glazes. Cone 10, in my opinion, is best reserved for reduction firings in fuel burning kilns. Cone 6 will increase your element life and reduce your electricity consumption a great deal.

I hear you all. I've seen the light so to speak. For right now, I am lucky to have an electric kiln and gas is not in the picture so I will be switching over to ^6. Of course I hate not using all the great ^10 glazes I have I may have to stick with the 10 until I use it up and all the clay too!

You can modify your cone 10 glazes to work at cone 6. They may not be identical, but close enough to warrant not throwing them out. Start with adding Gillespie (Gerstley) Borate. 3-5% will often do the trick. You can even use up your cone 10 clay. It will not be quite as tight as we really want it to be (that's another thread...), but still quite functional.

[Lucille Oka]

[Marcia Selsor]

When I first switched to ^6 from ^9 glazes in 1980, I used 10% Gerstley Borate as the rule for the modification rather than 3-5%. So you really need to test it and see what your glazes need in order to lower the temperature.
Marcia

[atanzey]

Marcia, Neil - any thoughts on how to 'guesstimate' how much 5-10% is for an 'already liquid' glaze?

By the way, I know we say it fairly often, but thanks for being willing to share info with those of us who are lower on the learning curve!

Alice

[Dharsi]

I went back and checked the front of my kiln and reread theowners manual. It appears there is a discrepancy. The front of my kiln reads KS1027, 2350 max temp Cone 10. However, when I read the "setting up yourkiln" section on page 2 of the Owner's Manual it states "KS1027 cone6." Things that make you go hmmmm. This kiln was new in 1996 and has beenfired probably 10 times in the past. It still looks like new. I did read the directions (my husband is aHealth and Safety Engineer, we read ALL instructions in this house) and thesection on the kiln sitter on page 7 states, "you get better results witha Junior cone one step hotter than your Senior cone, that is, a Cone 6 firingmay come out better with a Junior 7." I did use all new cones on therefire. It appears that cone 10 ispushing this puppy out of its comfort zone; and mine, so a switch to ^6 willwork for the time being. I will do a run with cones ranging from 4-7 and seewhere my temps are really ranging. If this kiln wasn't in such lovely conditionI would stick it in the back yard with a gas conversion kit! Thanks all for your input and I willcall Skutt as well.

[Dharsi]

After checking the price of golf clubs I called Skutt. They said that my kiln is indeed rated for ^10 and I should get someone trained to look at it I have a repair person on call but still plan to switch over to ^6 when I get this all ironed out. Thank you all for your help.

[neilestrick]

atanzey, on 18 April 2012 - 05:26 AM, said:

Marcia, Neil - any thoughts on how to 'guesstimate' how much 5-10% is for an 'already liquid' glaze?

By the way, I know we say it fairly often, but thanks for being willing to share info with those of us who are lower on the learning curve!

Alice

A slightly conservative estimate is that a 5 gallon bucket filled to within 3 inches of the top contains 9000 grams of dry material. You'll have to guesstimate from there.

[claydog]

Dharsi, on 17 April 2012 - 03:55 PM, said:

So I fired my kiln on Saturday for a ^10 glaze firing. If you remember I had asked about the kiln sitter in an earlier post. Well I adjusted the kiln sitter and after 8 hours the kiln sitter hadn't budged so I chickened out and pulled the plug. Everything was obviously under fired and my witness cones were standing tall. I checked my kiln sitter again, chatted up my old pottery instructor and gave it another go today. Well twelve hours in, again I pulled the plug. I couldn't see the cones even with sunglasses and blowing in with a straw to clear the atmosphere. Well after 20 minutes or so I pulled the peep again and I can see one cone standing. I wonder if they all are. I will know tomorrow. I guess I will spend some quality time on the phone with Skutt tomorrow and also hook up the pyrometer I had stuffed away in a drawer and finally found. I'm strongly considering three things:
1. Taking up golf instead
2. Switching to cone 6
3. Buying a new kiln
In the meantime I guess I'll take a nap.

Dharsi - I also have a KS1027 which is a 1996 model. I have seven years experience firing it. I am not an expert, but I have learned a few things over time.

I completely agree with responder neilestrick that there is very little reason to fire cone 10 in oxidation. I suspect you are aiming for cone 10 because that is what you were exposed to in school or wherever, where they had a big gas kiln for reduction firings. If what you are doing truly requires cone 10 work in oxidation then you are among an extremely small group of ceramic artists. So small, in fact, that you won't find many (any?) clay and glaze vendors advertising cone 10 materials for the oxidation environment. I'm not saying it is the wrong thing to do; I'm just saying it is not something you will find a lot of information about because most people don't do it. There are reasons for that. Different materials (clays and glazes) are good for different things because of their different physical properties. Different kilns are good at different things because of their design. With existing materials and kiln technology, you are facing a huge challenge in trying to achieve a cone 10 reduction look in an electric kiln. (If that is what you are after.) It's sort of like trying to fit a round peg in a square hole. Seriously. It can be done, but it's very, very hard.

Okay, that being said, let me make some suggestions that I hope will help you with your frustration:


1) Get a pyrometer. Witness cones are great, but they only tell you a story after the firing is done. A pyrometer is a device that measures the temperature in the kiln and displays that temperature on a dial or screen. A cheap ($80 or so) analog pyrometer will do just fine, though you can spend a lot more. I bought mine at the local caly store here in Boise (The Potter's Center), and I don't know how I lived without it. It's extremely easy to install; the KS1027 already has an opening in the outer steel skin for the probe. All you have to do is drill a little hole through the soft fire bricks, stick the probe in the hole and mount the gauge on the wall near the kiln. A cheap pyrometer isn't a precision device; it will be off by 100F +/-, but this is a pretty small error at 2400F. (Oh, BTW, make sure the pyrometer you buy has the temperature range capability you need.) Believe me, this is the best bang for your buck when it comes to getting the results you want from your kiln. It will teach you so much about what is happening during firing!

2) Read Chapter 2, Chapter 4 and Chapter 8 (at least) of Richard Zakin's book "Electric Kiln Firing". This will help you understand the basics of how oxidation environment materials (clays and glazes) work, and the best methods for firing your electric kiln. (Skutt is a great company but they really don't tell you everything you need to know in the kiln manual.) It is important to understand that how long it takes to reach final temperature depends on your firing schedule--how quickly or slowly you are ramping up to temperature. Clay and glazes mature according to the amount of work--energy applied over time--that is put into them during the firing process. I could spend two days getting to cone 6 if I wanted to be very very gentle in bringing my piece to maturity, or I could spend as little as six hours in the KS1027 getting to cone 6 if I thought my piece could take that kind of stress--not recommended. So when you ask, "How long should it take to get to cone 10 in my KS1027", I say, "It depends on your firing schedule." How long are you spending with elements on low, on medium, on high? What is the rate of temperature rise in your kiln? (Can't answer that one with witness cones.) When I fire to cone 6 with Laguna's Buff Sculpture clay I generally take a total of 12 hours to get there--3 hours ramping all three elements to low, then two hours at medium, then the remainder on high until the KS trips. Buff Sculpture has a lot of grog, so it can take a relatively quick ramp up to temperature. If I'm firing cone 6 porcelain, I generally use Richard Zakin's two-day firing schedule (page 255) with a long overnight preheat. That firing schedule takes almost 24 hours to get to cone 6. Going to cone 10 using any firing schedule will take a lot longer than going to cone 6, of course. In short, only 12 hours for cone 10 sounds way to short to me.

3) Ask yourself if you really need to work at cone 10 to get the results you want. There are a huge variety of materials out there with almost limitless possibilities for creativity at lower firing temperatures. Don't let people with "cone 10 bias" persuade you that cone 6 or lower is somehow not good enough for a "true artist". (I have found this bias very prevalent and am quite baffled by the attitude.) Great artists are not defined by temperature ranges and atmospheric conditions in a kiln. I am not a great artist but there are many great artists who use the same materials and work at the same temperature range as I do. I choose to work in cone 5/6 because I like the results I get for the type of work that I do. My dinnerware is dishwasher safe, and I have outdoor sculptural work that has been exposed to the Idaho climate for over a decade without any noticeable decay. I had people, even one university professor, tell me I couldn't do those things unless I worked at cone 10. Not true. Just look at the photos in Zakin's book (and others) and I think you'll agree. An added bonus of working at lower temperatures is that you are using a lot less energy. In fact some universities and large studios have moved to lower temperatures to save money.

4) Finally, don't give up. Firing a kiln, just like throwing or slabbing or doing anything else worthwhile, requires practice and experimentation. But firing doesn't have to be a mystery full of surprises. Yes, there are a lot of variables, but the process is understandable by anyone. And it can be very predictable once you get to know your materials and your kiln. With experience you can achieve consistently good results. Be patient with yourself and do lots of experimenting. Including, of course, firing your KS1027 at cone 10 if you want. You may teach the rest of us some new tricks!


Sincerely,
ClayDog

[Dharsi]

Claydog, I hear you. In my head I am already using ^6. I'll be cleaning up what I have now in ^10 and then switching over. I don't have a cone bias and will be perfectly happy working with a lower range clay and glaze. I am using ^10 because that is what my teacher used and the successful glaze recipes I have are, but I really don't mind starting over. Every day is a new adventure right? I will be happy when Elliot (my kiln) gets a clean bill of health and I can trust I am doing all I can to assure success.

I do have a Skutt Pyrometer spec'd for 2462 degrees. It has been in my husband's sock draw for 6 months or so. I won't run my kiln again without installing it. And yep, I located the precut hole in the kiln in which to install it. The book I will have to buy. I'm actually looking forward to the switch over from ^10 to ^6.

[Marcia Selsor]

atanzey, on 18 April 2012 - 05:26 AM, said:

Marcia, Neil - any thoughts on how to 'guesstimate' how much 5-10% is for an 'already liquid' glaze?

By the way, I know we say it fairly often, but thanks for being willing to share info with those of us who are lower on the learning curve!

Alice

I agree with Neil. A five gallon bucket is usually about 9000...unless using a lot of frit which is denser like a Majolica glaze would be 10,000 in a 5 gallon bucket or an ash or Magnesium glaze which are light , not dense materials. 9,000 is a good guestimate.
Marcia

[Matt Oz]

If you want a way to estimate how much glaze material vs water is in a bucket, you can use Brongniart's formula, it is discussed here in this Clayart thread.....Brongniart's formula

I'm guessing it would be easier to guesstimate though, but I thought I’d post it anyway.

[claydog]

Dharsi, on 18 April 2012 - 01:07 PM, said:

Claydog, I hear you. In my head I am already using ^6. I'll be cleaning up what I have now in ^10 and then switching over. I don't have a cone bias and will be perfectly happy working with a lower range clay and glaze. I am using ^10 because that is what my teacher used and the successful glaze recipes I have are, but I really don't mind starting over. Every day is a new adventure right? I will be happy when Elliot (my kiln) gets a clean bill of health and I can trust I am doing all I can to assure success.

I do have a Skutt Pyrometer spec'd for 2462 degrees. It has been in my husband's sock draw for 6 months or so. I won't run my kiln again without installing it. And yep, I located the precut hole in the kiln in which to install it. The book I will have to buy. I'm actually looking forward to the switch over from ^10 to ^6.

Hi Dharsi--
I re-read your e-mail and realized you already had the pyrometer. Awesome! When I was test firing my kiln, I took a temperature reading every hour or so and recorded it. Later I was able to enter the data in Excel and make graphs showing the temperature rise inside the kiln over the period of the firing. Comparing these graphs to the ones in Zakin, I was able to fine-tune my firing schedule to get the temperature ramp I needed for various clay and glaze combinations. I don't record the detail data anymore, unless I'm doing something new, but I can always refer back to my charts for what is "normal behavior" for my kiln. When my firing times start to lengthen, I can usually tell which element is failing if I've recorded the temperature data. Fun, if a bit geeky. :-) I confess to an engineering background.
There are paperback copies of the Zakin book for $30 new on Amazon. I guarantee you'll like it--he includes clay and glaze recipes and kiln repair along with lots of other great information in an interesting-to-look-at package.
Looking forward to hearing about your forays into cone 6.

[claydog]

claydog, on 18 April 2012 - 05:09 PM, said:

Dharsi, on 18 April 2012 - 01:07 PM, said:

Claydog, I hear you. In my head I am already using ^6. I'll be cleaning up what I have now in ^10 and then switching over. I don't have a cone bias and will be perfectly happy working with a lower range clay and glaze. I am using ^10 because that is what my teacher used and the successful glaze recipes I have are, but I really don't mind starting over. Every day is a new adventure right? I will be happy when Elliot (my kiln) gets a clean bill of health and I can trust I am doing all I can to assure success.

I do have a Skutt Pyrometer spec'd for 2462 degrees. It has been in my husband's sock draw for 6 months or so. I won't run my kiln again without installing it. And yep, I located the precut hole in the kiln in which to install it. The book I will have to buy. I'm actually looking forward to the switch over from ^10 to ^6.

Hi Dharsi--
I re-read your e-mail and realized you already had the pyrometer. Awesome! When I was test firing my kiln, I took a temperature reading every hour or so and recorded it. Later I was able to enter the data in Excel and make graphs showing the temperature rise inside the kiln over the period of the firing. Comparing these graphs to the ones in Zakin, I was able to fine-tune my firing schedule to get the temperature ramp I needed for various clay and glaze combinations. I don't record the detail data anymore, unless I'm doing something new, but I can always refer back to my charts for what is "normal behavior" for my kiln. When my firing times start to lengthen, I can usually tell which element is failing if I've recorded the temperature data. Fun, if a bit geeky. :-) I confess to an engineering background.
There are paperback copies of the Zakin book for $30 new on Amazon. I guarantee you'll like it--he includes clay and glaze recipes and kiln repair along with lots of other great information in an interesting-to-look-at package.
Looking forward to hearing about your forays into cone 6.

Oh, and Ceramic Arts Daily has the Zakin book for $30. That's where I got mine! If you're a Potter's Council member you get a discount from that.