terrim8 Posted February 2, 2017 Report Share Posted February 2, 2017 I don't totally agree with the argument that no ball clay = no plasticity. Fireclays and stoneware clays certainly have plasticity. Maybe not the same as ball clay, but they're way more plastic than kaolin. I'm with that thought also. The best clay body I've ever used is from Japan... and there is no ball clay in that. Mostly (90+%) it is a naturally occurring stoneware clay from 1/4 of a mile from where we are making pots, plus a little fireclay addition from Shigaraki. The processing is the key to the amazing plasticity and strength. Dug with heavy equipment, left outside in a pile to "age" for a year, run thru three separate blunging operations (first one screening out the bigger stuff), filter pressed, batch mixed in a blade type mixer, then pugged. Feels nothing like any clay body I've used in the USA. When you first touch it for something like wedging... you say "UGH!" Grainy, soft, mushy, come to mind. You'd swear that you'd never be able to work with it. Then you put it on a wheel............ best, ........................john PS> Fired to Orton cone 14. Doesn't mean we couldn't find something like that here! Sounds very interesting. Where exactly in Japan? The whole place is an island arc so its going to be some sort of volcanic derivative. This sounds like fun except for the second part - finding out what the land regs are for any particular district here. You have to deal with that even at the small hobby level. Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted February 2, 2017 Report Share Posted February 2, 2017 I'm going to shamelessly rat Terri out here because she won't blow her own horn: she's a mining geologist. She'll find the deposits you're looking for. Link to comment Share on other sites More sharing options...
glazenerd Posted February 2, 2017 Author Report Share Posted February 2, 2017 Callie: I have seen Terri use terms like magma, metamorphic, and call minerals by specific names: sorta knew she had a background. So why is such a common term such as plasticity; so hard to wrap words around? Nerd Link to comment Share on other sites More sharing options...
Callie Beller Diesel Posted February 2, 2017 Report Share Posted February 2, 2017 Because we're good with our hands, not our words. Link to comment Share on other sites More sharing options...
Min Posted February 2, 2017 Report Share Posted February 2, 2017 If it walks like a duck and quacks like a duck, it's a duck. Might be a mallard, or a wood duck or a pintail but it’s a duck. I don’t need to take it’s vital signs to know its a duck. Get your hands into the clay, make some pots and you know if it’s plastic. (think I might have to rent space in Bruce’s cave) Link to comment Share on other sites More sharing options...
Guest JBaymore Posted February 2, 2017 Report Share Posted February 2, 2017 If it walks like a duck and quacks like a duck, it's a duck. Might be a mallard, or a wood duck or a pintail but it’s a duck. I don’t need to take it’s vital signs to know its a duck. Get your hands into the clay, make some pots and you know if it’s plastic. (think I might have to rent space in Bruce’s cave) As a bit of a "tech weenie" myself .................... I have studied these aspects of the craft heavily .... so that I can own them well enough to just let them go and work very intuitively. I got this core philosophy from the "folk potter"....HAMADA Shoji. (Who had a formal post-secondary technical ceramics education before becoming a handcraft potter.) best, ........................john Link to comment Share on other sites More sharing options...
neilestrick Posted February 2, 2017 Report Share Posted February 2, 2017 I think lack of plasticity and shortness are two different things. Clay that is short has not been properly processed. If a clay body isn't run through a de-airing pugmill or isn't aged or isn't made from slip, it will be short. Too many tiny air pockets to create good bonds between the particles. Very plastic bodies can still be short. Shortness is a result of the mixing of the clay body. Plasticity in more about the nature of the materials themselves. Link to comment Share on other sites More sharing options...
glazenerd Posted February 2, 2017 Author Report Share Posted February 2, 2017 If every book or article I read on plasticity; quacked like a duck I would be good. Some quack, some mooo, and some bark like a dog. Nerd Link to comment Share on other sites More sharing options...
neilestrick Posted February 2, 2017 Report Share Posted February 2, 2017 If every book or article I read on plasticity; quacked like a duck I would be good. Some quack, some mooo, and some bark like a dog. Nerd Link to comment Share on other sites More sharing options...
neilestrick Posted February 2, 2017 Report Share Posted February 2, 2017 Neil: I wonder if anyone has ever tried using a wetting agent to speed up water absorption? Would be interested to see those results. Nerd A de-airing pugmill takes care of it quickly. Instant aging. Link to comment Share on other sites More sharing options...
Dick White Posted July 11, 2017 Report Share Posted July 11, 2017 Said by Nerd - "Why is the pottery industry not following the Atterberg limits more closely?" Does anybody really believe that an "industry" that sells clay bodies as cone 6-10 would limit itself by technical standards? dw Link to comment Share on other sites More sharing options...
Matt Oz Posted July 11, 2017 Report Share Posted July 11, 2017 stretchiness Link to comment Share on other sites More sharing options...
glazenerd Posted July 11, 2017 Author Report Share Posted July 11, 2017 Dick: This is the reason my friends stopped coming by, I think about these things. Have been reading books on clay formulation from back in the 50's and 60's: most of today's, terms came from back then. Soil sciences has greatly advanced since then. Seen a few potters state that soil science does not apply to clay; forgetting clay is just processed dirt. Matt.. That works, but I prefer high plasticity be called " play doughish. Nerd Link to comment Share on other sites More sharing options...
JohnnyK Posted July 11, 2017 Report Share Posted July 11, 2017 Maybe the word we are looking for is "malleability" as defined in www.vocabulary.com: Malleability is the quality of something that can be shaped into something else without breaking, like the malleability of clay. JK Link to comment Share on other sites More sharing options...
oldlady Posted July 12, 2017 Report Share Posted July 12, 2017 great suggestion, johnny. perfect definition. nerd, potters do not necessarily want to become scientists. they just want to work and play with clay. knowing exactly what is in it is not as important as what can be made with it. it is wonderful that some people want to find out exactly ''what'' and ''why'' and "when" but i believe the average potter just wants to know "that". Link to comment Share on other sites More sharing options...
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