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Fast firing unglazed stoneware beads and small components


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Hello ! 
I received my new skutt KS 609 and test fired it successfully given that I have never worked with a kiln sitter. I will mainly be using it to make small stoneware and porcelain components for jewelry and wall hangings. My question is has anyone tried to fast fire cone 6 unglazed stoneware and porcelain to vitrification ? I only want to fast fire for small beads and components. 

Also, is it safe to stack cone 6 stoneware plates without warping (slow fired of course) I’m  fairly new to mid fire clay bodies :)

Thanks! 
Asmaa

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What do you mean by fast fire? Because that kiln maxes out at cone 6, fast is not going to be very fast. And you'll only get to cone 6 if your elements are in perfect condition, so you'll likely only get around 35 firings before you need to change the elements. It would put a little less stress on the kiln if you only fired to cone 5, and it would be worth trying firing to cone 4 with a 20-30 minute hold to reach cone 5 through heat work.

3 hours ago, Asmaa Aman-Tran said:

is it safe to stack cone 6 stoneware plates without warping

I'm not sure what you mean here. Like dinner plates? Glazed? You can bisque fire them stacked, but you can't stack anything with glaze. I also wouldn't stack unglazed pieces in a cone 6 firing or they're more likely to warp, heat unevenly and/or crack.

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4 hours ago, Asmaa Aman-Tran said:

My question is has anyone tried to fast fire cone 6 unglazed stoneware and porcelain to vitrification ? I only want to fast fire for small beads and components

What do you consider fast fire and slow fire to be? Perhaps you are referring to once fire whereby the ware is fired from green through bisque to glaze in a single firing? Stacking at cone six will likely lead to warping as Neil mentioned above.

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18 hours ago, neilestrick said:

What do you mean by fast fire? Because that kiln maxes out at cone 6, fast is not going to be very fast. And you'll only get to cone 6 if your elements are in perfect condition, so you'll likely only get around 35 firings before you need to change the elements. It would put a little less stress on the kiln if you only fired to cone 5, and it would be worth trying firing to cone 4 with a 20-30 minute hold to reach cone 5 through heat work.

I'm not sure what you mean here. Like dinner plates? Glazed? You can bisque fire them stacked, but you can't stack anything with glaze. I also wouldn't stack unglazed pieces in a cone 6 firing or they're more likely to warp, heat unevenly and/or crack.

Thank you for your reply

 

18 hours ago, neilestrick said:

What do you mean by fast fire? Because that kiln maxes out at cone 6, fast is not going to be very fast. And you'll only get to cone 6 if your elements are in perfect condition, so you'll likely only get around 35 firings before you need to change the elements. It would put a little less stress on the kiln if you only fired to cone 5, and it would be worth trying firing to cone 4 with a 20-30 minute hold to reach cone 5 through heat work.

I'm not sure what you mean here. Like dinner plates? Glazed? You can bisque fire them stacked, but you can't stack anything with glaze. I also wouldn't stack unglazed pieces in a cone 6 firing or they're more likely to warp, heat unevenly and/or crack.

Thank you for your help and information. When I tested the kiln , the user’s  manual stated to fire to cone 04 on high setting which only took 2 hours to reach that temperature.  So I was thinking to fire my components to cone 5 or 6 on high. But I understand now that it would put too much stress on the elements and I definitely do not want to change anytime soon.  For my stacked ware , I’m thinking unglazed but fired to maturity not bisque. I’m guessing if I bush in between  the ware with alumina /wax they wouldn’t warp?! 

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17 hours ago, Bill Kielb said:

What do you consider fast fire and slow fire to be? Perhaps you are referring to once fire whereby the ware is fired from green through bisque to glaze in a single firing? Stacking at cone six will likely lead to warping as Neil mentioned above.

I’m referring to firing on the kiln sitter’s high setting . Sorry I haven’t specified it properly.  For the stacked ware, Since it will be unglazed, but fired to cone 6 , would wax/alumina help with warping? 

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@Asmaa Aman-Tran The alumina wax won't help with warping, just with keeping pieces from sticking to each other. Best to fire plates on the shelf not stacked to prevent warping.

Starting a firing in high is generally too fast for most work. Even if it doesn't blow up, you won't get good burnout of organic materials. Typically we do an hour or two on low, an hour or two on medium, and then high until done.

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10 hours ago, Asmaa Aman-Tran said:

would wax/alumina help with warping? 

No not likely but does help keep lids for jars from sticking or plucking at cone 6.  The high setting is almost always needed to finish a firing.. most kilns don’t have enough power to make it there at a reasonable final rate. Glaze fires can be fairly fast and most items will withstand 500-600 degrees per hour.. bisque fires generally half that speed to get enough time at a temperature to burn things out. The low medium high switches  have  reasons for their use.

Edited by Bill Kielb
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16 hours ago, neilestrick said:

@Asmaa Aman-Tran The alumina wax won't help with warping, just with keeping pieces from sticking to each other. Best to fire plates on the shelf not stacked to prevent warping.

Starting a firing in high is generally too fast for most work. Even if it doesn't blow up, you won't get good burnout of organic materials. Typically we do an hour or two on low, an hour or two on medium, and then high until done.

Thank you Neil for the information on the firing schedule. It sure helps a lot! 
 

 

 

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16 hours ago, Bill Kielb said:

No not likely but does help keep lids for jars from sticking or plucking at cone 6.  The high setting is almost always needed to finish a firing.. most kilns don’t have enough power to make it there at a reasonable final rate. Glaze fires can be fairly fast and most items will withstand 500-600 degrees per hour.. bisque fires generally half that speed to get enough time at a temperature to burn things out. The low medium high switches  have  reasons for their use.

I have a much better understanding now :)  Also I was wondering if I design the plates in a way that they have small feet on three (tripod)  or four points of the plate bottom surface and stack , would they warp anyways? 

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3 minutes ago, Asmaa Aman-Tran said:

I have a much better understanding now :)  Also I was wondering if I design the plates in a way that they have small feet on three (tripod)  or four points of the plate bottom surface and stack , would they warp anyways? 

Clays that fire to vitrification suffer from what is called 'pyroplasticity', which simply means that the clay gets soft as it approaches its melting point in the kiln. Porcelain is especially bad. So if you have a wide flat piece sitting on 3 or 4 small feet, it is likely to warp due to not being evenly supported all the way around. It all depends on the clay body you're using, though, and how thick the pieces are, so it may be worth running a test if you're willing to sacrifice a few pieces if they don't work out.

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4 minutes ago, neilestrick said:

Clays that fire to vitrification suffer from what is called 'pyroplasticity', which simply means that the clay gets soft as it approaches its melting point in the kiln. Porcelain is especially bad. So if you have a wide flat piece sitting on 3 or 4 small feet, it is likely to warp due to not being evenly supported all the way around. It all depends on the clay body you're using, though, and how thick the pieces are, so it may be worth running a test if you're willing to sacrifice a few pieces if they don't work out.

I see, I suspected that . I guess I won’t know until I try it :) thank you ! 

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