Confused Newbie w/new Skutt 818-3

[KellySnider]

I am a complete newbie to ceramics. I saw a mosaic tile project on stairs that I loved and wanted to duplicate for a backyard project and signed up for a week long intensive tile making class - I learned how to make and glaze the tile but the school took care of all the firing. Though they talked to us about the firing, we weren't involved in the process at all, but it seemed like it was something I could learn - especially as I researched kilns and saw that Skutt's had a touchscreen and pre-programmed settings - for what I'm making I only need to fire to cone 04 and cone 5 and will be using the same type of clay the school used. Maybe some day I will branch out - but this was to get me started on my project.

Fast forward to this week - the kiln arrived. We set it up and I did the test fire with the 04 cone on each of the 3 shelves - I ran the default 04 program and some 30 hours later (firing and cooling) I check the cones and all 3 are curved over with just the tips touching the shelves - I know they should be at 90 degrees.  Then I realize the default program was firing at "slow" not medium - not knowing anything about anything (maybe I jumped into this endeavor too soon with too little knowledge) I thought I would try the cone 5 with some test tiles I had glazed.  (For tile making you paint the raw clay, fire to cone 5, then do the detail work and fire to 04).  Those cones never even budged. I put an 04, a 5 and a 6 - the 04 bent slightly (maybe 1/4" and the 5 and 6 didn't bend at all, just turned white.

My monitoring app said the kiln reached the proper temperature in both firings so I don't know why the cones didn't respond like expected and while I can call Skutt and have them walk me through some things I'm at work today and until the weekend I won't be home with the kiln during business hours - so I thought I'd start some research on my own.

I apologize if these are questions I should know the answer to before I even bought a kiln -  I'm super excited about doing my project and wanted to dive in though now I'm feeling like I've bit off too big of a bite for never having worked with ceramics at all but, $5000 in equipment and materials later - I can't quit lol - gotta make it happen.  

Thank you all in advance for any insight and/or pointers you are willing to share.

[Min]

Hi Kelly and welcome to the forum! Congrats on your new kiln.

My first thought is there might have been a programming error. What temperature did the controller say the kiln reached with the cone 5 firing?

BTW- It's actually good that you did a slow firing with an empty kiln for the first firing as it conditions the elements. Building up an oxidized layer on the elements by doing an empty kiln firing will help with element life. 

 

[High Bridge Pottery]

1 hour ago, KellySnider said:

I check the cones and all 3 are curved over with just the tips touching the shelves - I know they should be at 90 degrees....

I thought I would try the cone 5 with some test tiles I had glazed...Those cones never even budged. I put an 04, a 5 and a 6 - the 04 bent slightly (maybe 1/4" and the 5 and 6 didn't bend at all, just turned white.

It sounds like you are saying the 04 firing cones are not right but they sound bent the right amount to me. Are you sure you did a cone5 firing and not cone05 as having the 04 start to bend sounds like you did cone05 by mistake.

[Dick White]

There are several issues in play here. First, about cone numbers - if you download a cone chart from this link https://www.ortonceramic.com/files/2676/File/Orton-Cone-Chart-F-022-14.pdf you will see the temperature/rates for every cone. Note that there is no cone 0, and cone numbers from 01 and up are actually running backwards, the temperatures getting colder as the number gets higher; cone numbers without a O in front of the number run as you would expect, the temperatures increase as the number gets higher. Thus, your array of cones 04, 5, and 6 do not relate to each other. There is 200+℉ difference between 04 and 5, which is why the 5 and 6 cones are unmoved when fired to 04. Cones above 3 are different colors in the box so you can easily tell them apart when loading the kiln, but the dye burns out during the firing, leaving them white. 

Second, about the accuracy of programmable kilns - they are not accurate out of the box. More often than not, they tend to fire hotter than the nominal temperature shown on the screen. The reported maximum temperature will correlate correctly to the Orton cone table linked above, meaning that the final temperature attained at slow speed will be lower than the temperature reported for medium speed, and higher yet for fast speed. That's just the way cones work - the bending process takes time as well as temperature to penetrate to the center of the cone (and the center of a ceramic piece). But back to the kiln accuracy - if the kiln is firing hotter or cooler than the cone bend, you can calibrate the controller to, in effect, fool it to add or subtract a certain number of degrees to what the thermocouple seems to be reporting, and thus adjust the actual results so that cone 5 (let's say) on the screen properly bends cone 5 inside the kiln. If you have never played with the controller adjustments, you should call Skutt and ask one of the technical reps to walk you through the process.

[KellySnider]

On 3/28/2023 at 9:30 AM, Min said:

Hi Kelly and welcome to the forum! Congrats on your new kiln.

My first thought is there might have been a programming error. What temperature did the controller say the kiln reached with the cone 5 firing?

BTW- It's actually good that you did a slow firing with an empty kiln for the first firing as it conditions the elements. Building up an oxidized layer on the elements by doing an empty kiln firing will help with element life. 

 

Thank you. And yes, looking back at the program, I did choose 05 instead of 5 - definitely “user error” - lesson learned! 

[KellySnider]

On 3/28/2023 at 10:24 AM, Dick White said:

There are several issues in play here. First, about cone numbers - if you download a cone chart from this link https://www.ortonceramic.com/files/2676/File/Orton-Cone-Chart-F-022-14.pdf you will see the temperature/rates for every cone. Note that there is no cone 0, and cone numbers from 01 and up are actually running backwards, the temperatures getting colder as the number gets higher; cone numbers without a O in front of the number run as you would expect, the temperatures increase as the number gets higher. Thus, your array of cones 04, 5, and 6 do not relate to each other. There is 200+℉ difference between 04 and 5, which is why the 5 and 6 cones are unmoved when fired to 04. Cones above 3 are different colors in the box so you can easily tell them apart when loading the kiln, but the dye burns out during the firing, leaving them white. 

Second, about the accuracy of programmable kilns - they are not accurate out of the box. More often than not, they tend to fire hotter than the nominal temperature shown on the screen. The reported maximum temperature will correlate correctly to the Orton cone table linked above, meaning that the final temperature attained at slow speed will be lower than the temperature reported for medium speed, and higher yet for fast speed. That's just the way cones work - the bending process takes time as well as temperature to penetrate to the center of the cone (and the center of a ceramic piece). But back to the kiln accuracy - if the kiln is firing hotter or cooler than the cone bend, you can calibrate the controller to, in effect, fool it to add or subtract a certain number of degrees to what the thermocouple seems to be reporting, and thus adjust the actual results so that cone 5 (let's say) on the screen properly bends cone 5 inside the kiln. If you have never played with the controller adjustments, you should call Skutt and ask one of the technical reps to walk you through the process.

Thank you - this explanation really helps me to understand better about the cones. 
 

I read the Orton attachment and I see where it says the tip touching the kiln shelf is considered insignificant so, I’m probably chasing a problem that doesn’t exist. 
 

And I checked my program last night after work and see I ran the 05 program, not the 5 - user error at its finest but also, a valuable lesson! 

[Babs]

Even more relevant!! If you had put c05 glazed stuff and fired to c5 you may have had the learning experience of having to grind everything off your new shelves!!

Step by step. You will find lots of help in these forums. No question is a silly one.

You may want to find out how folk go about packing tiles in a kiln to get optimum use of space.

 

[High Bridge Pottery]

If you put a cone04 in a cone5 firing you will probably end up with it sticking to the shelf unless you are making a cone pack with a bit to catch the melted cones in.  Turned out useful for problem solving this time but I wouldn't normally include an 04 unless you make something to catch the melting cone that's not your shelves.