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Chantay

Reading The Cone

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I have read the following, several times:

 

 

                                                                

Using Orton
Pyrometric Cones
Cone Numbers 022-14
Behavior of Pyrometric Cones
Typically, it takes 15 to 25 minutes for a cone
to bend once it starts. This depends on the
cone number.
The cone bends slowly at
first but once it reaches the half way point
(3 o’clock), it bends quickly.
When the
cone tip reaches a point level with the base, it
is considered properly fired. This is the point
for which temperature equivalents are
determined. Differences between a cone
touching the shelf and a cone at the 4 o’clock
position are small, usually 1 or 2 degrees.

 

 

So if I understand this correctly, if I want to reach cone 5, and it is all the way down, and cone 6 has started to bend, then I have over fired by about half a cone. I am using large cones in a plac.

 

Would someone please verify that I am understanding this correctly.

 

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ok this is for large cones only

lets say you want a perfect cone 5 end point fire-you would fire until the cone tip is equal to the base (almost touching the shelve)

Thats assuming your kiln is shut off at that point and does not climb or is on hold -for this cone to stay and not bend more the temp needs to cool from that point forward.The tip is same level as botton of base (large cones only)

If the cone 6 is bent a little you would not care as the fire is a cone 5 perfect end point.

I can post some photos if you need them of end point cones as I have a zillion cones laying around fired(they are not cone 5)

Mark

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Mark is exactly right, as usual.

 

But let me add that if you have a glaze that looks good at exactly 5, and bad at 5.5, then in my opinion you need a new glaze.  Good glazes should not be so sensitive to minor differences in heat work.

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If cone 5 is down or 90 deg bend than Cone 6 shouldn't have deformed at all. Cone 6 at a ramp rate of 108 deg F/hr would start to soften at around 2195 deg F but cone 5 would have been down to 90 deg bend at 2167 deg F.  As far as your glaze goes it probably doesn't care, probably cone 5 1/2.

David

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When the tip of the cone touches the base, you're there. The next cone up will have started moving, and the previous cone will be pretty flat. There will always be variations to this, but in general this is what happens. Soda, salt and wood firings can have crazy effects on cones.

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One caveat I would like to add is that all the info on tip touching base doesn't apply if you are using the large self supporting cones. Tip down to top of the wedge shaped support in that case.  

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I've never understood describing cone behavior with clock or angle references. The cones tend to curl or bend in ways that there could be many interpretations of these terms... In the larger community firings, we draw the cones every check, and use a finger to signal behavior. There are terms such as stiff, soft, bent, touching, and flat that are rather helpful. What does 45 degrees or 1 or 2 o'clock mean? Are you guys imagining vectors between the base and the tip of the cone? And why?

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I've never understood describing cone behavior with clock or angle references. The cones tend to curl or bend in ways that there could be many interpretations of these terms... In the larger community firings, we draw the cones every check, and use a finger to signal behavior. There are terms such as stiff, soft, bent, touching, and flat that are rather helpful. What does 45 degrees or 1 or 2 o'clock mean? Are you guys imagining vectors between the base and the tip of the cone? And why?

colby check this out and you will see what the clock vectors mean

http://digitalfire.c..._cones_193.html

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Thanks everyone.

 

Highbridge, the article really helped. 

 

Ray, your right.  I am wasting a lot of time messing around with a finiky glaze.  Works at cone 5 slow ramp, over done at cone 5 1/2 med ramp.

 

So I have gone back and studied my cone packs and kiln log.  Everything looks good, but now I am confident about it.  Using the kiln vent helped even out my kiln.  The bottom shelf is still about a quarter cone cooler than the top but it is not a problem.  When I pull the cones out of the kiln I mark them with the firing number and T, M, or B for top shelf, Middle, or Bottom.  Detailed notes, change only one thing at a time, and be ready to trash a bunch of work before getting it right.  Now you know what to do with that 100 bowls you made for practice. 

 

Next firing I get to see what happens when you accidently pour the freshly mixed glaze into the wrong bucket. I now have three gallons labled with a question mark. 

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