Tead Off wrote:What is not clear in this discussion is what is the processing of Yixing clay in order to make it throwable. Does it involve the addition of anything but water? Even Yixing clays are subjected to soaking in water in order to make them usable for the traditional slab-making technique that is regarded as 'true' Yixing. I've even read about a 'fermentation' process that some clays were put through, sometimes for years, before they were used for production
bears3x would know better, but I believe something besides liquid is needed to make it throwable. He theorizes that another type of clay would be blended with it, or smaller quantities of a "plasticizer" would be added. You can see some discussion over here:http://teadrunk.org/topic/68/does-anyon ... this-logo/
It's likely that kaolin is not added, because it would adversely affect color in the quantities that would be necessary to make the clay plastic enough to throw (usually 10-20%). Instead, ball clay with similar natural colorants to the yixing body it intends to plasticize would be a likely addition. Many ball clays ranging from white to dark brown exist naturally.
Even more likely, plasticizers like bentonite (an ultra plastic small particle clay) are added in portions of 2 percent or less. See here: http://digitalfire.com/4sight/material/
… e_106.html . There are other organic plasticizers that burn out more or less completely, but I'm not sure that yixing potters have access to these like we do in the US?
So yes, I think additives of some kind (besides water) are needed to make it possible to wheel throw zisha. For slipcasting, I'm not 100% sure, but I think it can be done simply by making essentially a slip out of the zisha (increasing its moisture content).
My understanding from talking to bears3x is that modern processing methods mostly
eliminate the need to weather the clay for literally years before use. Of course, we all hear the stories about such and such clay being stored for years, and while it's possible that some of them are true, I believe that it's no longer necessary to weather / decompose the raw material for extended periods of time before use.
Also, while I can't comment on the truth of any of the claims, nor on what type of material is being used in the video, take a look at this page (and the video it links to):http://www.freehead.com/forum.php?mod=v ... 972&page=1
(refers to the prejudice against wheel thrown "Yixing", and links to a video of someone making pots using this method).
originally linked to from:http://houdeblog.com/?p=115