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G 200, G 200 Hp And What Else.

Feldspar

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#1 porcelainbyAntoinette

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Posted 18 April 2017 - 03:50 PM

Hi Guys. What is the latest changes on G 200 and or the HP? 

I saw some Spanish Feldspar somewhere at $3 per lb, which is way over what I would like to spend. I know Custer and the soda spars that is available, but before I make the final changes to some porcelain clay recipes, I would like to look at all the possible options. Thanks for any information. 

Antoinette

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#2 glazenerd

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Posted 18 April 2017 - 05:49 PM

Mavahir runs less than $1 a lb.



#3 porcelainbyAntoinette

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Posted 18 April 2017 - 10:09 PM

Thank you Glazenerd. That was quick. I see the biggest differences is in the Calcium and the Magnesium. I wonder how much I should worry about that or if I must find something in addition to fill the deficiency up. Whiting maybe in small percentages, or dolomite that contain both calcium and magnesium. 

 

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#4 glazenerd

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Posted 19 April 2017 - 06:23 AM

It all depends what your goal is in porcelain. I keep the elemental metal oxides on the very low side.

MGO test2

 

Bar 3 at the top has magnesium causing a grey hue.

Bar 5 has higher levels of titanium.

 

Calcium does make a good floc for porcelain, but you need very little to do the job. All my porcelain recipes have a straight 1% whiting addition. To keep the body high white, then elemental oxides must be kept very low. You can blend your fluxes as well: 50/50 Nep Sy & Mahavir if you like to balance the KNaO. High levels of sodium will cause it to dry a bit quicker, and high levels of potassium will off-gas more so than sodium.

 

Happy Formulating-

Nerd



#5 porcelainbyAntoinette

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Posted 19 April 2017 - 11:53 AM

Thanks. Just have to shake the gray matter in my brain around again. Just finished with a series of tests with the 200HP. It is frustrating when materials change so fast. 
I try to stay away from natrium based materials. Neph Sye is one of them. I prefer shorter clay over thixotropic clay. 

Will let you know if something comes of it. 

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#6 bciskepottery

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Posted 19 April 2017 - 07:21 PM

http://www.lagunacla...ir_Feldspar.pdf

#7 JBaymore

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Posted 19 April 2017 - 10:21 PM

 I prefer shorter clay over thixotropic clay. 

 

Thixotropy in clay is a total no-go for me.  I'd rather work with wet beach sand.

 

best,

 

..................john


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#8 glazenerd

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Posted 20 April 2017 - 06:18 AM

Thixotropy used in conjunction with clay body makes me smile. Another one of those pottery world expressions that I have yet to comprehend its use.



#9 JBaymore

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Posted 20 April 2017 - 08:56 AM

Thixotropy used in conjunction with clay body makes me smile. Another one of those pottery world expressions that I have yet to comprehend its use.

 

Get some poorly formulated cone 6 porcelain.......... throw with it with some added water.... don't keep anything........ put the pots and the throwing slop in a container.........let it sit a while.... reclaim it... and try to use it again on the wheel.  ;)

 

best,

 

....................john


John Baymore
Adjunct Professor of Ceramics; New Hampshire Insitute of Art

Former Guest Professor, Wuxi Institute of Arts and Science, Yixing, China

Former President and Past President; Potters Council
 

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#10 porcelainbyAntoinette

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Posted 20 April 2017 - 10:47 AM

Also hard to carve. As the solubles settle to gel, nothing works until the particles get heated again. When I was teaching in Europe in 2016, someone gave me a piece of Mont Blanc porcelain. I managed to throw a small piece, but when I tried to trim it, it broke the foot like hard toffee that dropped on the floor!



#11 glazenerd

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Posted 20 April 2017 - 05:16 PM

 

poorly formulated cone 6 porcelain

the root cause..



#12 Kaolinwasher

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Posted 21 April 2017 - 09:37 AM

Nothing wrong with Custer feldspar  it has 72.47 silica 15.24% alumina and 10.87KN so you need less silica in the porcelain. and its cheep , I do use mahivar as well they must float out the siica because it has only 67% silica and 17.5 alumina and 14.5 KN but its expensive 



#13 porcelainbyAntoinette

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Posted 21 April 2017 - 10:00 PM

Hmm, worth looking into the Custer too. Some years back it was said that the g 200 was more pure.  I just compared the two and it seems that the Custer is even less complicated.  Someone said it changed,; I wonder if I still have the old one.........bought mine about 10+ years ago. 

Thanks Kaolinwasher.......I will check and definitely consider testing that in a recipe or 2 







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