Failed to reach temperature

[Momo]

Hi,

After only ever doing low-firings, I attempted my first high firing yesterday but my kiln simply refused to go higher than 1165 celsius. It was very frustrating as I had spent quite a lot on stoneware clay and glazes. What are the reasons why my kiln wouldn't reach the temperature that I'd set? I noticed that the temperature rise slowed down significantly after it reached 1140 celsius and for the last half hour it didn't move from 1165. Now, I'm guessing,  I'm left with bowls that aren't food safe. 

Any advice would be appreciated. 

Thank you. 

[Bill Kielb]

I am assuming you want to make it to come 6 or 1222C.  Obviously it would be important that your kiln have fully functioning elements and that they are not excessively worn. So a likely first step would be to check they are all working and what is their measured resistance as compared against a new element.

Generally if the element resistance has risen 10% from new condition it is time to replace.

I have measured elements that have changed by 10%  which then had the measured effect  of decreasing the kiln output by 30% when at or near the top temperature. 

 

[Momo]

Thank you. I did wonder about the elements so will definitely get them checked and replace if necessary. Can I replace with a different element that will withstand higher temperatures or are all elements the same? 

Thanks again.

[Bill Kielb]

You really should change with those that are designed for your kiln. Depending upon the kiln model they may offer longer life  element options which usually are different materials but still match the wattage of the original design.

As long as your kiln was rated above cone six, you should be able to fire to that. Most electric kilns are rated to cone 10 which allows them to last longer fired only to cone 6  A lighter duty arrangement would be a kiln rated to cone 8 (top temperature) It should still  fire  to cone 6  but probably not last as long as one rated to 10 and fired to 6.

what model and make kiln are you  firing? 

[Momo]

It's a Cambridge 401

[Bill Kielb]

I believe that is the control so yes if you were confident in how it was programmed to reach temperature then by all means have the kiln itself checked for wear and tear.

[Momo]

Thanks. I've just contacted the guy who installed it for me. 

 

[Chilly]

I think Cambridge 401 is the controller, not the kiln.

If the kiln is rated to 1260C, as mine is, this is the hottest it would ever get with brand new elements on a warm day.  Every time it i fired, the elements wear a little, and over time it will not get as hot.

[JohnnyK]

There should be some kind of specification plate on the kiln which will tell you what the make, model, operating input voltage and temp rating of the kiln is. Find that and you'll have a starting point for your exploration into your problem...

JohnnyK