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Stoneware Clay Properties

stoneware plasticity pliable throwing

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#21 glazenerd

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Posted 22 February 2017 - 06:44 PM

Lady:

 

I do make pots and practice throwing when I get time. I must say however that I enjoy the testing and experimentation more than anything else. I have been considering selling my larger kilns; some equipment and just experimenting and throwing small pots from time to time. Spent seven years in the hole studying clay and glaze before I came out of hiding, perhaps it is time to go back into the hole and see what I come up with in another seven years, I find the chemistry very fascinating- what can I say.

 

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#22 curt

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Posted 22 February 2017 - 09:04 PM

I suspect some of the questions you have may be much studied scientifically, by soil scientists, civil engineers, etc. They may already have identified paradigms, testing procedures, etc.. in fact, I think there is every possibility that the standards you are looking for are already out there, and could be applied to the ceramic arts without too much difficulty.

I for one am wholly in favour of some standards. Convincing clay manufacturers to accept them or potters to use them may be another matter if this thread is any indication. If they get a critical mass of acceptance amongst potters, then manufacturers might just roll over. But it will take work to show why and how such measures are useful. Time to don your missionary garb...

The whole discussion in this thread about force to move clay, density, mass, particle size, etc. is very familiar from discussions I have seen on shear stress in soils.

See the following link, and also references to Tresca (the "father" of plasticity science) within it.

https://en.m.wikiped...strength_(soil)

#23 glazenerd

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Posted 07 March 2017 - 07:57 AM

The difference between porcelain and stoneware is:

 

1. Kaolin/s have no appreciable ionic platelet charge, ball clay/s do.

2, Porcelain has a single platelet layer (SAS), ball clay/s have double layer platelets. * reason ball clay is "plastic"

3. Kaolin has no appreciable reactions to PH levels, ball clay/s do. PH levels are the primary indicator of reduction potentials; which in turn predict the plasticity of clay. This is also the reason sodium is the flux of choice of kaolin (porcelain), and potassium is the flux of choice for stoneware (ball/fire clay). Kaolin requires the higher isoelectric points produced by sodium in order for the platelet to absorb water onto their surfaces. Stoneware (ball/fire clay) have their own platelet charges and require much less isoelectric variation to absorb water.

 

For this and other useless information go to: www.manthatwasboring.com

 

To think I only needed an RPO meter to determine clay plasticity: who knew?

 

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#24 terrim8

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Posted 07 March 2017 - 02:42 PM

I used to walk by the engineering lab that did this sort of stuff, as in this article, and thought it was a snooze.  http://www.sciencedi...169131710003601Talk about boring. Making pots & glaze is lots of fun- pity the poor sods that are stuck in a lab measuring clay plasticity and writing tombes on the subject.


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