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cone 10 bmix firing to cone 6?


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#1 kmcquhae

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Posted 24 September 2012 - 09:29 PM

I attended a hand building & extruding course a MISSA this summer. My problem is the clay recommended for this course was cone 10 Bmix, i fire at cone 6, all the items i produced have been bisqued and waiting to be glazed.

Is it too late to apply cone 6 slip to my cone 10 bisqued platters and refire in another bisquing. If i can do this, will my platters then be vitrified?

#2 Mark C.

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Posted 24 September 2012 - 11:12 PM

I attended a hand building & extruding course a MISSA this summer. My problem is the clay recommended for this course was cone 10 Bmix, i fire at cone 6, all the items i produced have been bisqued and waiting to be glazed.

Is it too late to apply cone 6 slip to my cone 10 bisqued platters and refire in another bisquing. If i can do this, will my platters then be vitrified? (No they will not be)


The only way to vitrify a cone 10 body is fire to cone 10-cone 6 is cone 6
as far as the slip it may work just fine with another bisque or may peel off only testing will tell. You may not have to bisque it again just glaze over in a raw state. You are in an experimental stage with this anyway-why are you putting cone 6 slip on to begin with? To cover a stoneware body with say white slip or some other reason?
How about finding a cone 10 firing place?
Just an idea.
Mark
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#3 kmcquhae

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Posted 25 September 2012 - 12:00 AM


I attended a hand building & extruding course a MISSA this summer. My problem is the clay recommended for this course was cone 10 Bmix, i fire at cone 6, all the items i produced have been bisqued and waiting to be glazed.

Is it too late to apply cone 6 slip to my cone 10 bisqued platters and refire in another bisquing. If i can do this, will my platters then be vitrified? (No they will not be)


The only way to vitrify a cone 10 body is fire to cone 10-cone 6 is cone 6
as far as the slip it may work just fine with another bisque or may peel off only testing will tell. You may not have to bisque it again just glaze over in a raw state. You are in an experimental stage with this anyway-why are you putting cone 6 slip on to begin with? To cover a stoneware body with say white slip or some other reason?
How about finding a cone 10 firing place?
Just an idea.
Mark

I have my own cone 6 glazes that i am really happy with. To use someone else's glazes and firing, is really scary. I don't want to ruin my work. If i glaze/fire at cone 6, how will this effect my work?




#4 Mark C.

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Posted 25 September 2012 - 01:32 AM

The clay will not be as hard-no big deal unless you are selling it as its not fully vitrified .
Is this functional ware? for you or others?
I guess the glaze will fit ok but I have NEVER tried this.
Mark
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#5 kmcquhae

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Posted 25 September 2012 - 10:38 AM

The clay will not be as hard-no big deal unless you are selling it as its not fully vitrified .
Is this functional ware? for you or others?
I guess the glaze will fit ok but I have NEVER tried this.
Mark


i did spray glaze one of the pieces, it turned out beautiful cone 6. If it is not vitrified, does this mean it will break down in time with washing and usage?

#6 kmcquhae

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Posted 25 September 2012 - 10:50 AM

thank you Mark for the quick response. Functional work with the intent to sell. I have two options for glazing cone 10, one is in the area, but his kiln will not be fixed until the new year the other is in Whistler, that will be a very expensive firing, hotel, food and firing.

#7 Iforgot

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Posted 27 September 2012 - 09:39 PM

I fire soldate-60 which is a cone 10 body at cone 5 all the time and it turns out fine, but yet again soldate is extremely versatile. I think you will be safe for a cone 6 firing with cone 10 b-mix.
Derek VonDrehle

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#8 VirginiaEllen

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Posted 26 October 2012 - 01:10 PM

I fire soldate-60 which is a cone 10 body at cone 5 all the time and it turns out fine, but yet again soldate is extremely versatile. I think you will be safe for a cone 6 firing with cone 10 b-mix.


I have been using Soldate 60, fired to cone 6. I haven't had any issues, but recently was wondering if maybe I should switch to something similar, but made for cone 6. I called Laguna and they didn't know what would happen with firing it at cone 6. Has anyone had an actual problem with Soldate 60 fired mid-range? My glazes are all good, I haven't had any unusual issues with my work. I find Soldate 60 to be a great all-around clay to work with and it is inexpensive.

#9 bciskepottery

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Posted 26 October 2012 - 04:07 PM

Neither B-mix 10 nor Soldate 60 fired at Cone 6 will be vitrified. The clay bodies will be immature and be more absorbent than if fired to Cone 10 where they mature and achieve vitrification. For functional ware, vitrification should be a key consideration for your clay body (think leaking vases, vases leaving watermarks on wood table tops). If you are working at Cone 6 and making functional ware, use a clay body that matures and vitrifies at Cone 6; if you want to work at Cone 10, pick a Cone 10 clay body. If you like to alternate between the two, pick two different clay bodies suitable for the temperature you are working. One size does not fit all.

#10 Mark C.

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Posted 26 October 2012 - 08:31 PM


I fire soldate-60 which is a cone 10 body at cone 5 all the time and it turns out fine, but yet again soldate is extremely versatile. I think you will be safe for a cone 6 firing with cone 10 b-mix.


I have been using Soldate 60, fired to cone 6. I haven't had any issues, but recently was wondering if maybe I should switch to something similar, but made for cone 6. I called Laguna and they didn't know what would happen with firing it at cone 6. Has anyone had an actual problem with Soldate 60 fired mid-range? My glazes are all good, I haven't had any unusual issues with my work. I find Soldate 60 to be a great all-around clay to work with and it is inexpensive.

I forgot said
(I fire soldate-60 which is a cone 10 body at cone 5 all the time and it turns out fine, but yet again soldate is extremely versatile. I think you will be safe for a cone 6 firing with cone 10 b-mix. )


The problem for me as a functional potter selling my wares is that yes it appears to each of the above posters that this under fired clay works great. It does not and cannot as over time things go astray. The feedback I get is from customers is they buy a vase or lotion bottle or bowl and then it weeps on the furniture and they ask me why does their pot not work and are skeptical about buying more. I have had more of this now that mid range is getting more accepted.If you want to fire mid range buy mid range clay .
This is a pet peeve I will say as its an uphill battle . First educating the public is one issue but getting potters to learn and accept what goes wrong is another when they use an unverified body for functional ware
(well my mother said if you can-t say something nice do not say anything at all) so I will leave it at what Bciskepottery said
For functional ware one size does not fit all.
Mark
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www.liscomhillpottery.com

#11 Kabe

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Posted 26 October 2012 - 09:15 PM

You could take a piece you were willing to break. Glaze it, fire it to cone 6 and put it through a vetrification test to see what the absortion rate is. Just a thought. Might be an interesting bit of information for everyone. Sort of educational. happy firing



#12 bciskepottery

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Posted 26 October 2012 - 11:19 PM

Absorbency is measured using unglazed clay. You just fire the plain unglazed clay to temperature and then do the absorbency test.

Laguna says Soldate 60 has 2% absorbency at cone 10 and B-Mix 10 has 1.2% absorbency at cone 10. No data given for cone 6. Baltimore Clayworks, where I buy my clay, lists Soldate 60 with a range of cones 06 to 10 and B-Mix 10 with a range of cones 8 to 10.

#13 kmcquhae

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Posted 27 October 2012 - 08:29 AM

Absorbency is measured using unglazed clay. You just fire the plain unglazed clay to temperature and then do the absorbency test.

Laguna says Soldate 60 has 2% absorbency at cone 10 and B-Mix 10 has 1.2% absorbency at cone 10. No data given for cone 6. Baltimore Clayworks, where I buy my clay, lists Soldate 60 with a range of cones 06 to 10 and B-Mix 10 with a range of cones 8 to 10.



#14 kmcquhae

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Posted 27 October 2012 - 08:35 AM

long story short. I have made arrangements to fire my cone 10 platters at another studio, using their glazes and kiln firing at cone 10. thank you for all the responses, if i am going to sell my work i want it to be the best for my customer. that is to fire cone 10 at cone 10.

#15 neilestrick

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Posted 27 October 2012 - 10:58 AM

Is it too late to apply cone 6 slip to my cone 10 bisqued platters and refire in another bisquing. If i can do this, will my platters then be vitrified?


You cannot apply slip to a bisqued piece. It will flake off. Slip is clay, and follows the same rules for attachment as all clay: no attachments any drier than leather hard.
Neil Estrick
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#16 OffCenter

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Posted 27 October 2012 - 12:22 PM

long story short. I have made arrangements to fire my cone 10 platters at another studio, using their glazes and kiln firing at cone 10. thank you for all the responses, if i am going to sell my work i want it to be the best for my customer. that is to fire cone 10 at cone 10.


Good decision. I can't believe how careless so many potters are about firing functional pots to maturity. You should ALWAYS test any clay body you work with first to see if it leaks when fired to the temp you intend to fire to. You can't depend on what the manufacturer prints on the box. It's in their interest to put the widest range of maturing cones possible on the label. Obviously, when a label says cone 5 to 10 that is BS. That clay is either overfired at cone 10 or (more likely) underfired at cone 5, 6 and 7. Also, Do Not depend on a glaze to stop leakage. Almost all glazes have some crackle in them even it it is too small to see with the naked eye. It's not like it's hard to make a little unglazed cylinder, fill it with water and leave it on a piece of paper overnight! I wish more potters would get sued for ruined furniture because they were too lazy or stupid to test their clay before making a coffee mug or vase out of it.

Jim
E pur si muove.

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#17 bciskepottery

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Posted 27 October 2012 - 01:16 PM

The "carelessness" often starts in studios where people first learn to throw or handbuild. The studio where I took classes, and taught, offered both Cone 6 electric firing (normal works) and an optional Cone 10 gas firing. Too often instructors advised students to get a Cone 6 to 10 class clay (they had a choice of over 20 clay bodies to choose from) so you could have the option of high firing if you wanted. And there was little to no discussion of absorption, vitrification, etc. and choosing a clay body for particular work. As part of my handbuilding classes, I gave students a handout that listed all the studio clay bodies, firing temperatures, shrinkage, and absorption (using manufacturer's data) and tried to convey the idea of "no one clay body fits all". Not sure how much that helped, but it was a try. And clay manufacturers don't seem to help either and cite multiple firing temperatures for their products.

#18 Ben

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Posted 29 October 2012 - 10:34 AM

The "carelessness" often starts in studios where people first learn to throw or handbuild. The studio where I took classes, and taught, offered both Cone 6 electric firing (normal works) and an optional Cone 10 gas firing. Too often instructors advised students to get a Cone 6 to 10 class clay


There is no such thing as a clay with a 4 cone range. A clay body is properly vitrified at a certain amount of heat work (cone, not temp).
Over that it is overfired and vice versa.
Teaching otherwise is incorrect and a disservice to the student.
Teach them correctly from the get go. It isn't that complicated of a concept. Compare it to baking a cake.

You can bake it a little cooler for a little longer, or hotter for a shorter time BUT if you stray to far from that sweet spot of heat work that cake is gonna be raw in the middle or over done.
Clay is the same.

Then teach them that if the piece doesn't need to hold liquid or be as strong as the clay can be that underfiring is fine. Non-functional pieces have different needs than functional ones.
Look at raku. You think raku ware is vitrified? No, and that is fine. It just isn't meant to hold your soda pop either so it all works out.




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