Defective cones?

[dianen]

I've been getting very inconsistent results in a new, little test kiln at ^04. Using exactly the same program with almost identical loads, my witness cone would sometimes bend close to the shelf and sometimes not bend much at all. It dawned on me that I was pulling the cones from two different boxes, so decided to test the cones themselves the other day in my larger kiln. I placed them right next to each other, and you can see the result in the attached image. I've contacted Orton about it, but have yet to receive a response. Both boxes are clearly labeled as ^04 cones, and the cones themselves are similarly marked. I can't think of any other explanation other than one of the boxes contains defective cones. But which one?? One of the boxes is older than the other, but I don't remember which one's which. Do these things have an expiration date?! Anyone else ever encounter something like this? 

 

[Mark C.]

Cones do not go bad or age out . I have used cones that are 40 years old with great success . The oly issue is if thay ever got wet-then they can go bad.meaning weird readings.

My guess is the two cones you show where in slighly different areas which you will fine evne in that tiny kiln will have different temps all over it.The cone shoes the time temperature heat work that happens in that given spot you place it.

100% of the time it's not the cone but the kiln that is differnt temps.

Since you are using the same program the other thing  that changes is the load -that is whats different every time and the cones will show that as well as it effects temp as well.

[dianen]

Mark, thanks for answering. I wish I could attribute it to spacing, but the cones were right next to each other, maybe about a 1/4" apart. None of the pieces being fired were close to them.  I'm quite sure  that when the cones didn't bend fully in my test kiln, they came from one box, and when they bent fully, they came from the other. They've never gotten wet. In the end, it probably doesn't matter that much if I'm achieving exactly ^04, but the dilemma is not knowing which one to believe. It's like finding two different so-called 12" rulers that are different sizes. An additional "proof" that something is wrong with at least one these boxes is that I get consistent results at other temperatures with other cones. My larger kiln will be more affected by load size, but the test kiln is so very tiny that I can't imagine there's much of a difference in temperature from one spot to another. 

[liambesaw]

I mean the difference between those two cones could be as little as 10-20 degrees.  One is slightly underfired and the other is slightly overfired.  You need to get another defective box so you can have one that is right between them.

[Bill Kielb]

1 hour ago, dianen said:

Mark, thanks for answering. I wish I could attribute it to spacing, but the cones were right next to each other, maybe about a 1/4" apart. None of the pieces being fired were close to them.  I'm quite sure  that when the cones didn't bend fully in my test kiln, they came from one box, and when they bent fully, they came from the other. They've never gotten wet. In the end, it probably doesn't matter that much if I'm achieving exactly ^04, but the dilemma is not knowing which one to believe. It's like finding two different so-called 12" rulers that are different sizes. An additional "proof" that something is wrong with at least one these boxes is that I get consistent results at other temperatures with other cones. My larger kiln will be more affected by load size, but the test kiln is so very tiny that I can't imagine there's much of a difference in temperature from one spot to another. 

 

I am with @liambesaw in that there is virtually no difference.

My issue with all the lowfire Orton cones is they don’t tend to bend in a picture perfect fashion. They tend to bend mostly at the hips which I believe is the result of the cross section and saving some material but just speculation there.

Here is another point to ponder, radiation! At the end of your firing most of the heat will be by radiation, then conduction, then very little by convection.. Why is that relevant? Because if either of your cones has more of a clear vision or line of sight to your elements they will absorb more heat energy.

Could be the difference in bend from cone to cone in your picture. Two cones next to each other but one being able to see more glowing elements.

Lastly cones are made of glaze that would melt just like glaze  at about 6 cones higher temperature. Their formulation is pretty established and consistent so they last a long time with the exception of if they get wet or contaminated usually with a wet substance.

An 04 Cone is - 0.3:0.7 flux ratio, 0.2 iron, 0.3 Alumina, 0.2 Boron, 3.8 silica hey, it’s a glaze!

 

[Mark C.]

Bill and Liam are on it such small differences in these (o4) low fire cones can be from anything and the temp difference is so small.

[dianen]

Thanks, guys. I guess if I wanted to be more scientific about it, I could mark the exact spots on the shelf where the cones are to be placed and do repeated firings, alternating the positions of the cones from the two boxes. It would at least prove that there must have been some sort of manufacturing difference between the lots. Bottom line, though, I accept your argument that even if there is such a difference, it is inconsequential. Worries be gone!

[Chilly]

15 hours ago, dianen said:

finding two different so-called 12" rulers that are different sizes

I have those if you need to borrow them.......

[Min]

18 hours ago, liambesaw said:

I mean the difference between those two cones could be as little as 10-20 degrees

Maybe even less than that. From the time the tip gets to the 3:00 position to tip touching is only 5 degrees for this cone 10 example. I think that if people want to really fine tune their firings using 3 cones would be a good idea. With @dianen  example of fired cones above if there were a ^05 warning cone and a ^03 guard cone you could look at those to determine which of the ^04 cones were more valid. Really nit picking moot point though, especially if this is for a bisque firing. 

[Mark C.]

Yes guard cones on each side would help nail this down. But for a bisque who cares.

[dianen]

Yes, it's a bisque fire, and you have all persuaded me that I shouldn't care -- but again, it's like the business with the rulers. Without a trustworthy measurement standard, the universe descends into pure chaos.   Not to nitpick or anything.

[Bill Kielb]

18 minutes ago, dianen said:

Yes, it's a bisque fire, and you have all persuaded me that I shouldn't care -- but again, it's like the business with the rulers. Without a trustworthy measurement standard, the universe descends into pure chaos.   Not to nitpick or anything.

I throw you another twist, on occasion I have had a cone 11 guard cone bend as much or more than the cone 10 firing cone. Universe is way out  of order on those days!

[dianen]

Oh, Bill, thank you! It's so good to know someone else has apparently been living in the alternate universe where cones don't behave as expected.

[fergusonjeff]

I don't use cones in my regular electric firings, but I do in wood firings.  My higher temp cones (9-12) bend backwards at the tip first then drop forward.  Provides a nice early warning.

[Mark C.]

My Last fire last week both cone 11 and cone 10 went down exactly togther in unison in same cone pack -this has happened many times-both cones show end points in same cone pack .Its not defective cones just normal wierd stuff with temps and reflected heat and downdraft flow.