Historical Notes on Kaolin hi 



kaolinite is the basis of kaolin, and theoretically pure kaolin would 

 contain nothing but kaolinite; but kaolinite is also the basis of nearly 

 all common clays. In these it is mingled with larger or smaller quan- 

 tities of various minerals by which its properties are more or less ob- 

 scured. Hence the chemical examination of almost any burned pot- 

 tery, even of common bricks and the crudest and cheapest of earthen- 

 ware, will disclose the presence of derivatives of kaolinite which might 

 be, and as a matter of convenience frequently is, interpreted as due 

 to the presence of small quantities of kaolin, instead of larger quantities 

 of ordinary clay containing kaolinite. It is quite certain that the 

 bodies of many early Han pottery bits contain more or less kaolin or 

 kaolinite, yet they are not porcelains. The utilization of kaolin for 

 potter's work on a large scale is not a "discovery," but rests on experi- 

 ence. It was incidentally found, and its employment was gradually 

 extended through a selective progress in the enrolment of materials. 



The distinctive structural character of porcelain is based on the 

 combination of three elements, — a porous, opaque skeleton; a trans- 

 parent, dense bond permeating the skeleton; and a thin, glassy glaze on 

 the outside, which merges imperceptibly with the body. In typical 

 porcelains the opaque, porous body is kaolin or aluminous derivatives 

 therefrom, which, through their resistance to the effects of heat, sup- 

 ply a rigidity that prevents the ware from deforming in the kiln. 

 Also its opacity clouds the transparency of the other elements to 

 translucency. The kaolin skeleton is permeated and bound together 

 by a more fusible glass or enamel-like substance (petuntse), which 

 makes the ware strong, impervious, and translucent. The glaze serves 

 for the perfection and increased lustre of the surface. Kaolin alone 

 makes a ware which is porous, fragile, and opaque. Petuntse alone 

 softens in the kiln, and runs together into a lump. 



For the lover of art the salient and distinctive points in porcelain 

 are the glaze and its organic combination with the body. The body, 

 as a rule, is invisible: it is the glaze that is intended to appeal to the 

 spectator and to convey an esthetic impression. 



F. Hirth 1 was the first to call attention to a statement of the 

 Taoist adept T'ao Hung-king (452-536), to the effect that in his time 

 "white clay" (pat ngo 6 M), or kaolin, was much utilized in painting, 2 



1 Ancient Chinese Porcelain, p. 131. 



1 What this means has not been explained by Hirth, who translated, "much 

 used for painting pictures." It cannot be understood, of course, that kaolin was a 

 pigment applied in pictorial art to paper or silk. Technically there are but two 

 possibilities: kaolin may have been utilized in architectural painting for the decora- 

 tion of walls, being applied to a colored background, or it may have been employed 



