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Bisque Firing Cone 6 Stoneware


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Hi everybody! I'm completely new to the forums here, and while I've gotten a great amount of information through lurking, I'm still pretty new to much concerning ceramic arts. I really apologize for all my questions -- I started working with ceramics back in high school, but I've never truly done it on my own, so I feel like I'm starting all over again!

 

I have been working with a Flint Hills Cone 6 Buff stoneware, and I'm getting together some practice pots to do my first firing with ever.

 

My first question -- I don't see any specific recommendations on the box for this clay, so I assume I should bisque fire to cone 06-04? But specifically speaking, would cone 04 be best to fire to?

 

Also, I have an old kiln that I purchased on Craigslist that states on the machine, do not fire any higher than cone 6! When I get home I can get specific model and maker information, but I do know it's not one of the well known manufacturers like Skutt. Do you think that it will be safe to glaze fire to cone 6 in this kiln later down the road? I will be using only commercial glazes to start with for consistency and stability while I'm still learning how to fire and everything.

 

I really appreciate any insight that you might be able to share! I never realized how fully indepth and complex ceramic arts could be, so any help navigating the topic would be amazing.

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You may have an old Kress kiln. I had one that said to fire only to cone 6... which I did. There should be no problem as long as the firebrick  in the kiln is intact. That means no open cracks to the outside wall of the kiln. You can patch minor cracks with available patching compound found at your local clay dealer. If big chunks are missing you may have problems.

 

Other than that, the worse that might happen is that the elements are tired and either don't produce enough heat to reach cone 6 or take forever to get there.

 

The old Kress I had was square and had solid brick walls. very heavy. The kiln took a long time to bring the high density walls up to temperature, but when it shut down, the temperature dropped very slowly, which is good in most cases.

 

As far as bisque fire.  I fire to a cone 07. Some fire higher. some lower. I'd start out low.

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Don't apologize for questions! Most of us love them because it gives us a chance to show off how knowledgeable we are even if we have to fake it. There's no set cone to bisque to. I use a lot of different clays (commercial, mixed from scratch, dug) and usually just go to cone 012-010 simply because that's plenty high enough to give the bisqueware handling strength, and just right for absorbing glazes. The only reason I bisque higher (08) is to give very large bowls a little more handling strength and dug clay and Lizella Red to cone 04 to burn out organics. So for a nice, clean commercial clay, bisque to 010 or to be extra cautious bisque it to 08-06. Don't bisque higher than 08-06 unless you have bloating problems with the clay. Firing higher than you have to is a waste of time, energy and wear on the kiln.

 

As for glaze firing. Don't fire higher than cone 6. I don't think you have to worry about it if you sometimes hit 7 when aiming for 6 but don't push it higher than that.

 

Jim

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How about e-mailing or calling the clay manufacturer?  My ^6 clay boxes don't have a recommended bisque, but the manufacturer told me 04.  I had been going to 06 and having dipping runs , too thick glaze layers and pitting problems with their speckled clay.  I bisque now to 05 almost 04 and things improved when I got hotter.

Depends on what you are trying to do.  If you are bisquing lower, you will need thicker glazes than for tighter bisque, Is my understanding.

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Most clay manufacturers will recommend bisque firing to cone 04. It's a good number to make sure everything is burned out that needs to be, and saves them a lot of phone calls from customers who have problems due to bisque firing too low. The difference in wear and tear and cost of firing to 04 vs 08 is tiny.

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Most clay manufacturers will recommend bisque firing to cone 04. It's a good number to make sure everything is burned out that needs to be, and saves them a lot of phone calls from customers who have problems due to bisque firing too low. The difference in wear and tear and cost of firing to 04 vs 08 is tiny.

 

Still, there's no reason to fire higher than you have to. If you're not completely happy with what happens when you fire to 010 then go to 06 or even 04, but over time the difference between firing to 010 and 04 or even 06 and 04 is significant in the extra time you waste, the extra electricity you waste, the extra heat in the studio, and the extra wear on the kiln. Don't depend on the manufacturer (They aren't paying your elec bill and they often err on the side of caution. Almost every commercial cone 6-7 commercial clay I use is rated cone 5 by the manufacturer. At cone 5 none of them are completely mature.) Test and decide for yourself what is the best bisque cone for you.

 

Jim

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I bisque to cone 07, like Jim. Why waste electricity. At school, I bisque to cone06, as I also glaze fire student work to 06. That way I can have greenware in the bottom to bique, and glaze ware up top.

Neil, my students brush glazes on, so no need to count. I think they CAN count to six...not sure.

TJR.

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I bisque to 04 on Highwaters Buncombe White cone 5-6 clay. I know some who fire lower but 04 works for me.

 

Sure it works for you but you're firing to the extreme end of bisque range for no good reason. 06 or 08 might even work better for you and you would not only be saving yourself time and money but helping the planet just a little bit.

 

Jim

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I also bisque to 04 because the body is a little bit tighter and less absorbent, which gives me greater control when dipping glazes. Helps keep my students from getting the glazes on too thick, since they don't always know how to count to 6.......

 

Great, that works for you, but may be a lousy cone to bisque to for the guy who made the original post. Maybe 04 makes his clay body a bit too tight and less absorbent. Application makes a difference, too. Brushing, dipping, and spraying each need different degrees of absorption. I can see how in a classroom setting your rules work, but to encouraging newbie studio potters to fire to the extreme end of the bisque range just encourages newbies to be lazy and just fire to cone 04 because it works instead of finding a cone that works BETTER for them. Just following the "rules" instead of testing and learning. 04 is the extreme end of the bisque range (I know some people may bisque a little higher--I have.) and, once again, not only is cone 06 or lower a better cone to fire to for most purposes, 06, 08, 010 save time, wear on the kiln, energy, money, studio comfort, and the environment. Pam firing to cone 04 just because it works is like her driving a tank to the grocery store because it gets here there.

 

Jim

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I also bisque to 04 because the body is a little bit tighter and less absorbent, which gives me greater control when dipping glazes. Helps keep my students from getting the glazes on too thick, since they don't always know how to count to 6.......

 

Great, that works for you, but may be a lousy cone to bisque to for the guy who made the original post. Maybe 04 makes his clay body a bit too tight and less absorbent. Application makes a difference, too. Brushing, dipping, and spraying each need different degrees of absorption. I can see how in a classroom setting your rules work, but to encouraging newbie studio potters to fire to the extreme end of the bisque range just encourages newbies to be lazy and just fire to cone 04 because it works instead of finding a cone that works BETTER for them. Just following the "rules" instead of testing and learning. 04 is the extreme end of the bisque range (I know some people may bisque a little higher--I have.) and, once again, not only is cone 06 or lower a better cone to fire to for most purposes, 06, 08, 010 save time, wear on the kiln, energy, money, studio comfort, and the environment. Pam firing to cone 04 just because it works is like her driving a tank to the grocery store because it gets here there.

 

Jim

 

 

True, 04 may not be ideal for everyone. Never said it was. Why are you jumping on me? I gave the reasons why it works for me, and why the clay manufacturers recommend it. And 04 is not the extreme end. I've seen people bisque as high as 01. Just putting out options so the OP can make an informed decision.

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I also bisque to 04 because the body is a little bit tighter and less absorbent, which gives me greater control when dipping glazes. Helps keep my students from getting the glazes on too thick, since they don't always know how to count to 6.......

 

Great, that works for you, but may be a lousy cone to bisque to for the guy who made the original post. Maybe 04 makes his clay body a bit too tight and less absorbent. Application makes a difference, too. Brushing, dipping, and spraying each need different degrees of absorption. I can see how in a classroom setting your rules work, but to encouraging newbie studio potters to fire to the extreme end of the bisque range just encourages newbies to be lazy and just fire to cone 04 because it works instead of finding a cone that works BETTER for them. Just following the "rules" instead of testing and learning. 04 is the extreme end of the bisque range (I know some people may bisque a little higher--I have.) and, once again, not only is cone 06 or lower a better cone to fire to for most purposes, 06, 08, 010 save time, wear on the kiln, energy, money, studio comfort, and the environment. Pam firing to cone 04 just because it works is like her driving a tank to the grocery store because it gets here there.

 

Jim

 

 

True, 04 may not be ideal for everyone. Never said it was. Why are you jumping on me? I gave the reasons why it works for me, and why the clay manufacturers recommend it. And 04 is not the extreme end. I've seen people bisque as high as 01. Just putting out options so the OP can make an informed decision.

 

 

Sorry. Didn't mean to jump on you. It's just that people here know that you're one of the most knowledgeable posters here and you recommending bisque firing to 04 will influence people to fire to cone 04 without testing and learning for themselves. That's the only point I was trying to get across but maybe over-did it a bit.

 

Jim

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Thank you so much everyone! I really appreciate all the input. After taking what you've guys have said, I think what I will do is a test fire to cone 06, and perhaps another test fire to cone 04 with another batch. I intend to brush glazes on, so I assume I wouldn't need quite as tight of clay body as bisquing all the way up to cone 04 would get it, so cone 06 may be a good point for me to try first at. (Is that the correct conclusion to make?)

 

Our local ceramic store is pretty great too but they are a small, small business that operates during my full-time work hours, so it's not always as quick of a reply from them. Plus, I really appreciate the depth and comprehensiveness of the answers, I'm the kind of person that likes to know EVERYTHING going into something like my first test firing.

 

After my first test firing, which is realistically a week or two out yet, when I'm looking through the finished bisqued pieces, are there any specific attributes or qualities that I am looking for to determine whether or not I needed to fire higher/lower, or will this be evident after seeing how the glaze fire works out?

 

Also, Bob, you were correct! My kiln is indeed an old Cress. I've attached a couple pictures just in case anybody is interested in the exact model or anything like that.

 

Thanks again everyone, you are really helping!

 

 

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  • 3 years later...

For the record: clay continues to expand up to 2050F, when metakoalin begins to form spinel. Clay being applied as aluminosilicate/polymorph. The fact this clay is buff in color should tell you that it is higher titanium, and slightly higher in iron. This also means slightly higher levels of carbon will also be present: so Neils' recommendation is correct. Clean porcelain and white stoneware can be bisqued to a lower cone because there are no carbons to speak of.

 

Nerd

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