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Self Glazing Cone 04 Porcelain


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#21 AnnaM

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Posted 23 January 2014 - 11:36 PM

Goodness thanks Irene!! I have just found Susan Peterson's recipe funnily enough! Did you throw with it? I'm assuming it's not very plastic..

#22 Norm Stuart

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Posted 24 January 2014 - 03:11 AM

When the only plastic material is 50% kaolin, a lot is going to depend on the plasticity of the Kaolin you choose.  EPK from Florida is more plastic with most, being a small particle size kaolin.  But if you EPK you'll want to try replacing some of the EPK with Vee-Gum bentonite, even though EPK is more plastic than most kaolins, as the frit and Wollastonite don't have any plasticity - although Wollastonite is naturally compressible and fibrous. Using 45% EPK and 5% Veegum might a good place to start.

 

http://digitalfire.c...kaolin_291.html

http://digitalfire.c...eegum_1672.html

 

Another choice is PVC (Plastic Vitreous Clay or Plastic Vitrox) which is slightly fluxy with 5% potassium like a feldpar.  You might end up eliminating part of the potassium in your frit.  http://digitalfire.c..._clay_1152.html

 

More plastic kaolins are mined in France and New Zealand.

 

Susan Peterson's ^04 porcelain uses ball clay to create the plasticity, so it fires less white.

25%  China Clay
25%  Ball Clay  (OM4)
40%  Ferro Frit 3110
10%  Silica
 

 

Generic China Clay is not very plastic at all, so you could probably use a more plastic kaolin and reduce the amount of ball Clay.



#23 AnnaM

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Posted 24 January 2014 - 08:31 AM

Thanks Norm. I ended up making about 500gms to test out a recipe of 50% Frit (I used Ferro 3/4110), 25% ball clay, 25% Kaolin. It was not very plastic at all, but throwable - very gently and slowly!

I threw a decent cup out of about 250gms of it which is drying now and the other half of it, Im letting dry out a bit more to see if it's a bit easier for me to throw when it's a bit harder.

I've got a couple of recipes to try tomorrow, and I'll try Susan Peterson's as well. I'm quite encouraged by Irene's experience!

Will post results as they are fired ;)

#24 Mudslinger Ceramics

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Posted 27 January 2014 - 05:58 PM

Hi Anna

 

I only threw with the clay twice and yes it wasn't very plastic, was a bit better for smaller handbuilding shapes but couldn't hold its own wieght in taller forms.

 

I used it for slip casting and got variations on off-white or cream depending on the kaolin/ball clays used but for some things the warm colour was quite beautiful. Don't know the Australian/US equivalents of the clays so can't recommend one.

 

The high frit content meant some of the forms would soften a little in the firing especially if thin cast and/or when pushed to to ^03 (1100C) and in some cases when pushed to ^02 would gently collapse in on themselves looking like soft fabric folding....very beautiful for sculptural applications I thought.

 

Hope your experiments are going well, post some pictures!!

 

Irene


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It will stick with you and show up for better or for worse in spite of all you or anyone else can do.'

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#25 AnnaM

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Posted 27 January 2014 - 10:11 PM

I've got the results of 4 batch tests cooling down in the kiln as we speak! I'll post the photos tonight.

One thing I've learned in the last few days is that I will never take plasticity for granted again! I started feeling like I couldn't throw and had to mix up a few hundred grams that was only ball clay and Frit to prove to myself that I still could!

The whole reason that I wanted to try this was because my little kiln only gets up to Cone 03, and I need a body that will vitrify at that low temperature. The ball clay I've used is quite a greyish one and (in order to get a whiter clay body) was wondering whether adding Frit to my fine white earthenware clay would lower it's vitrification point? Does that sound like a silly idea? Is there any reason you couldn't muck around with a pre-mixed commercial clay?

#26 Norm Stuart

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Posted 28 January 2014 - 03:20 AM

Ferro Frit 3110 is called "body frit" because it's commonly added to clays to flux them to Cone 6 or Cone 2 - which ever cone you prefer.

 

Ferro Frit 3110 is a high expansion frit, so you might prefer some other.  http://digitalfire.c...t_3110_349.html

 

Perhaps 3195 which melts at the same temperature.  http://digitalfire.c...t_3195_356.html

 

And if you want to add white plasticity to your porcelain, buy some VeeGum.  It's far more costly than common bentonite, but very white firing.   http://www.axner.com...-vee-gum-t.aspx

 

Like any artist, try new things!

I've got the results of 4 batch tests cooling down in the kiln as we speak! I'll post the photos tonight.

One thing I've learned in the last few days is that I will never take plasticity for granted again! I started feeling like I couldn't throw and had to mix up a few hundred grams that was only ball clay and Frit to prove to myself that I still could!

The whole reason that I wanted to try this was because my little kiln only gets up to Cone 03, and I need a body that will vitrify at that low temperature. The ball clay I've used is quite a greyish one and (in order to get a whiter clay body) was wondering whether adding Frit to my fine white earthenware clay would lower it's vitrification point? Does that sound like a silly idea? Is there any reason you couldn't muck around with a pre-mixed commercial clay?



#27 AnnaM

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Posted 28 January 2014 - 03:52 AM

Norm, does Vee gum have another name down here in Australia? (Bentonite is quite cheap down here, by the way, only about $5 a kg at one of my suppliers and even cheaper if you buy in bulk!)

Do they both basically perform the same function? What sort of percentage in a clay body would be sufficient?

And when you say 4110 is an expanding body, what does that mean? Is it plausible to think that a glassy body could be made up of just frit, kaolin & veegum or bentonite?

#28 AnnaM

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Posted 28 January 2014 - 07:58 AM

The results so far are encouraging, even the extreme experiments are interesting.

 

Attached File  Batch F.jpg   58.05KB   5 downloads

 

The last one of this lot was the 1:1 ball clay / frit mix just for curiosity's sake and because I was hanging out for some plasticity by this stage. Fired too hot to c03, next time will fire to 04. It was super good to to throw with :)  Lovely glossy surface despite the fact that it melted!

 

 

 

Attached File  Batch E.jpg   163.45KB   4 downloads

 

This one is 15 parts frit / 10 ball clay / 10 whiting.  More like a white stoneware as the whiting made it opaque. A bit more plastic but not much more and doesn't seem glassy at all.  Fired to c03.

 

 

Attached File  Batch D.jpg   137.13KB   2 downloads

This one was 1:1 frit and kaolin just to see what it would do. It cracks. Lovely and white though. Not self glazing. I'm assuming that's because the melting point of the kaolin is so high? Also an interesting lesson in what happens when you try to throw a substance with not a scrap of plasticity! It's like throwing butter. Fired to Cone 03.

 

 

Attached File  Batch C.jpg   128.28KB   2 downloads

 

This one also has no plasticity and was another bit of an extreme test just to see if it could be useful. I think it's good from a sculptural point of view to know what these combinations will do. This is 10 parts kaolin / 10 4110 frit / 3 whiting / .5 epsom salts ( I read somewhere that the plasticity can be increased by adding Epsom salts to the water, but I don't know whether it did add any plasticity really, not at that proportion anyway).

 

 

Attached File  Batch B.jpg   115.23KB   2 downloads

 

These ones were fired to c03, and although they flopped they have the most desirable colour. This composition was 10 kaolin / 25 ball clay / 10 whiting / 65 frit 3110.   It's a lovely very slightly creamy off white and is beautifully satiny, but I'll make up another batch tomorrow and only fire to 04 to see if it still has that lovely finish and doesn't flop.  I see what you mean Irene about the potential for using for sculpture, the possibilities are endless! When you hold the more open one to the light you can see that its translucent

 

Attached File  Batch A.jpg   59.31KB   4 downloads

 

This one was fired to Cone 04, it was the original 25 kaolin / 25 ball clay / 50 frit recipe. Not much plasticity, translucent, an off white colour and looks amber when light comes through it.  This recipe didn't become glossy or satiny on the surface (which is why I fired the next firing to c03).  Interesting though. I'm going to refire this one to c03 to see whether it goes glossy and stays up, or flops.

 

I'll get some bentonite tomorrow and mix some batches with it, plus mix and refire batch B & F at C04.  Its a great exercise, very steep learning curve!



#29 Norm Stuart

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Posted 28 January 2014 - 05:02 PM

You'll soon understand why some porcelain makers fire their bowls in refractory "bowl setters" so the plastic bone china or porcelain, which can get plastic if fired to its full maturity cone, can lay down into the setter shape. 

 

A refractory cup-setter on the left.  The bone-china cup on the right sits on the cup-setter while being fired in the kiln, to retain its shape.  There is even a handle setter.

dencycup3.jpgdenbycup6.jpg

A porcelain which "self-glazes" is very likely to require this for larger pieces, as the reason for the glassy glaze on the surface is that entire body is the same, glassy and plastic.

 

Most factories use a less fluxed-porcelain which retains its shape better, so does not require plate setters, but these porcelains require glaze. http://science.howst...-made-video.htm

www.youtube.com/watch?v=bpaFi-kIlNU

 

Ceramic Arts Daily member Chris Campbell firing porcelain bowls in bowl setters to help them retain their shape.

gallery_18533_680_112219.jpg

 

 

The results so far are encouraging, even the extreme experiments are interesting.

 

attachicon.gifBatch F.jpg

 

The last one of this lot was the 1:1 ball clay / frit mix just for curiosity's sake and because I was hanging out for some plasticity by this stage. Fired too hot to c03, next time will fire to 04. It was super good to to throw with :)  Lovely glossy surface despite the fact that it melted!

 

 

 

attachicon.gifBatch E.jpg

 

This one is 15 parts frit / 10 ball clay / 10 whiting.  More like a white stoneware as the whiting made it opaque. A bit more plastic but not much more and doesn't seem glassy at all.  Fired to c03.

 

 

attachicon.gifBatch D.jpg

This one was 1:1 frit and kaolin just to see what it would do. It cracks. Lovely and white though. Not self glazing. I'm assuming that's because the melting point of the kaolin is so high? Also an interesting lesson in what happens when you try to throw a substance with not a scrap of plasticity! It's like throwing butter. Fired to Cone 03.

 

 

attachicon.gifBatch C.jpg

 

This one also has no plasticity and was another bit of an extreme test just to see if it could be useful. I think it's good from a sculptural point of view to know what these combinations will do. This is 10 parts kaolin / 10 4110 frit / 3 whiting / .5 epsom salts ( I read somewhere that the plasticity can be increased by adding Epsom salts to the water, but I don't know whether it did add any plasticity really, not at that proportion anyway).

 

 

attachicon.gifBatch B.jpg

 

These ones were fired to c03, and although they flopped they have the most desirable colour. This composition was 10 kaolin / 25 ball clay / 10 whiting / 65 frit 3110.   It's a lovely very slightly creamy off white and is beautifully satiny, but I'll make up another batch tomorrow and only fire to 04 to see if it still has that lovely finish and doesn't flop.  I see what you mean Irene about the potential for using for sculpture, the possibilities are endless! When you hold the more open one to the light you can see that its translucent

 

attachicon.gifBatch A.jpg

 

This one was fired to Cone 04, it was the original 25 kaolin / 25 ball clay / 50 frit recipe. Not much plasticity, translucent, an off white colour and looks amber when light comes through it.  This recipe didn't become glossy or satiny on the surface (which is why I fired the next firing to c03).  Interesting though. I'm going to refire this one to c03 to see whether it goes glossy and stays up, or flops.

 

I'll get some bentonite tomorrow and mix some batches with it, plus mix and refire batch B & F at C04.  Its a great exercise, very steep learning curve!

 



#30 AnnaM

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Posted 28 January 2014 - 06:55 PM

I don't mind glazing as well, I just really want a clay body that is vitrified at lower temps, so I don't have to do my glaze firings away from home! Makes it difficult having a kiln that only reaches 1100°!

#31 AtomicAxe

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Posted 01 February 2014 - 07:10 AM

I always did like experimenting with self glazing clay bodies when I was in college.  really any clay body can become self glazing ... it really just comes down to finding that point of fluxing a clay body to where it still holds it shape with in a cone or two higher than you fire but the surface flux melts at the cone you fire to or a little under.  I had one I called a volcanic clay which I used silicon carbide in with high flux on an iron-ish rich clay body ... it fired to cone 10 and would sort of form a bubbled skin looking like course rock for some of my sculptures.  Mind you, it still had warping and distortion in thin areas because of the self fluxing, so that had to be overcome with thickness. 



#32 Norm Stuart

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Posted 01 February 2014 - 04:02 PM

Veegum in Australia?  What you want is any white-firing type of calcium-bentonite or montmorillonite or smectite or fullers earth or hectorite.  These are all volcanic ash which have been decomposed over millions of years.  Most bentonites contain too much iron, so fire off-white.  Some off-white bentonites can be added up to 5% to a white body without affecting the final whiteness of the ware.  Some unwashed bentonites come with soluble salts which can be countered with 1/3% barium carbonate.

 

The whiteness comes from selecting white sections of the ore rock.  Veegum is a brand name of one type of white firing bentonite made by Vanderbilt industries in the US.  Macaloid is a brand name popular in the UK.  I think both are listed in ceramic materials in Australia -

 

Ask your Australian supplier if their Trugel 100 Bentonite is white firing.  It seems the most common type available there.

 

Norm, does Vee gum have another name down here in Australia? (Bentonite is quite cheap down here, by the way, only about $5 a kg at one of my suppliers and even cheaper if you buy in bulk!)

Do they both basically perform the same function? What sort of percentage in a clay body would be sufficient?

And when you say 4110 is an expanding body, what does that mean? Is it plausible to think that a glassy body could be made up of just frit, kaolin & veegum or bentonite?



#33 High Bridge Pottery

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Posted 01 February 2014 - 05:42 PM

Really good read all of this. Enjoyed reading your posts especially Norm.

 

I remember reading something about a self glazing clay that while it was drying it had some water soluble flux that was brought up to the surface. This then went onto turn the outer layer of clay into a glaze.

 

Have I just been confused in my reading or is this a different technique? This way seems to be making a clay that is 100% glaze/clay hybrid.



#34 AnnaM

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Posted 01 February 2014 - 09:50 PM

No you're not mistaken. I have come across some recipes that have some types of salts in them that come to the surface as the greenware is drying. I'll see if I can find them again for you ;)

#35 AnnaM

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Posted 01 February 2014 - 09:53 PM

I also tried lowering the m.p.of some white earthenware as well which has been successful, I'll post some photos later. I just need to work out how low to bisque at!

#36 Norm Stuart

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Posted 01 February 2014 - 11:49 PM

Many of the soluble salts which migrate to the surface are fluxes at the right temperature with the right materials, but they more often create a white surface called scumming.

 

Really good read all of this. Enjoyed reading your posts especially Norm.

 

I remember reading something about a self glazing clay that while it was drying it had some water soluble flux that was brought up to the surface. This then went onto turn the outer layer of clay into a glaze.

 

Have I just been confused in my reading or is this a different technique? This way seems to be making a clay that is 100% glaze/clay hybrid.



#37 Mudslinger Ceramics

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Posted 07 February 2014 - 07:38 AM

Hi Anna

 

Just checked in again and noticed you are an Aussie girl....all good, I live in Sydney.

 

Checking back over my notes the whitest china clay I used for the Cone 4 body was Eckalite1, the warm creamy colour was from Clay Ceram.   I did use Frit 4064 (lead, no longer available)  and Frit 4110 (alkaline). I only used the regular bentonite the uni had. Though I've heard about Macaloid and Veegum the 3 catalogues I have from NSW Pottery Supplies, Walkers Ceramics and Keanes Ceramics do not mention different types of bentonite.....I just accepted the ivory white that Eckalite made and the cream from the Clay Ceram..... I love bonechina's whiteness so if you find a way to make it really white let me know!

 

Your soft shapes are SO sweet!!.....I don't think all pottery needs be rigidly round or 'perfect'......that is the beauty of the pottery from so many other cultures who are not slaves to the 'mechanical' roundness of an electric wheel......I have an electric wheel which finds more use as a glaze mixing tool these days!!! I use a truely beautifully made kick wheel which allows individuality and variations in a bowl's shape depending on my kick rhythm....have come to admire the 'wonky pot' after watching Japanese master Ryoji Koei demonstrate at uni many years ago.....

 

.......so find the soft shapes and ivory white of your Cone 4 Porcelain experiments lovely......show us more when you can.

 

Irene


Mudslinger Ceramics :   www.mudslingerceramics.net

 

'Don't worry about your originality. You couldn't get rid of it even if you wanted to.

It will stick with you and show up for better or for worse in spite of all you or anyone else can do.'

                                                                              - Robert Henri


#38 AnnaM

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Posted 07 February 2014 - 08:05 AM

Oh you're in Aust! I'm in Melbourne. Was just about to post some more images. It takes me a while because we have bad internet where we are! Hang on.

#39 AnnaM

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Posted 07 February 2014 - 08:16 AM

This one has only a really small amount of Bentonite, about 5%. It doesn't really seem to make much difference to the colour, it definitely has a slight warmth to it which I like better than the stark white. oh and this one was only fired to the very bottom range of cone 04 so it has that almost metallic type sheen.

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#40 AnnaM

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Posted 07 February 2014 - 08:30 AM

Irene, I just looked at your work it's beautiful. You mightbe interested in Amy Kennedy's work, lovely delicate porcelain as well.




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