The Beginnings of Porcelain in Chin

Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: It is of course possible that the potters had learned to adjust the qualities of the glaze by small additions of alkali and iron oxide. Slight variations in the quantity of either of these substances greatly influence the physical properties of the glaze. This table cannot give more than a rough...
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Purchase of this book includes free trial access to www.million-books.com where you can read more than a million books for free. This is an OCR edition with typos. Excerpt from book: It is of course possible that the potters had learned to adjust the qualities of the glaze by small additions of alkali and iron oxide. Slight variations in the quantity of either of these substances greatly influence the physical properties of the glaze. This table cannot give more than a rough approximation of the quantities of the two ingredients of the mixture, as the losses of volatile matter in both limestone and clay during burning cannot be computed with accuracy. The table suggests that not far from one part of limestone to two parts of clay were employed. We may safely conclude that this glaze was made by adding pulverized limestone, lime, or milk of lime to the material from which the body of the pottery was made. The modern Chinese glaze for porcelain is made by mixing lime with one of the two ingredients of which they make the body. This process seems to be peculiar to China. Conclusions. -- At the time this ware was made, the potters had already acquired a high degree of dexterity. Many of the things that they accomplished in the fabrication of this pottery required technical skill of no mean order. The engobe coat, without which no satisfactory glaze could be made upon so porous a ware, was used. The expansion of the glaze has been very accurately adjusted to that of the body. The glaze is remarkably brilliant for one free from lead. The glaze has no large bubbles, nor are small bubbles numerous enough to cloud the ware. On the other hand, they made the glaze too thick, and they could not prevent it from running during the firing. With potters as skilful as these, the discovery of methods of overcoming the porosity of the ware, and thus making it a true porcelain, should be only a matter of time. As the engobe coat is porcelain, it is quite possible th...