Tribute from the Mineral World

Tribute from the Mineral World

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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1912 edition. Excerpt: ...If this is the proportion desired the workmen can easily obtain the necessary mixture by adding water t0 the clay which is stirred, or "blunged," so as to be of uniform density, until his pint measure when full tips the scales at the twenty-four ounce mark. Of course, it is possible to reduce all the materials to a perfectly dry state, mix them in the desired proportions, and bring them to a workable plastic state by the addition of water; and this method is used in some of the large factories. The usual method, however, is to make slips of the different materials, each slip of predetermined strength, mix them all together, and then remove the excess of water. China-clay, the other substance coming in the first class of materials, is a white, earthy substance, easily pulverized. In this country it is very generally called kaolin. Like the blue clay it is found in many different countries, China and Japan, Germany, France, England, and several other European countries, as well as in certain places in America. As it contains many impurities wherever found, it must be washed before being used for making pottery. This is done by adding large quantities of water until a thin "solution" is made, when the impurities, which are heavier than the kaolin, settle to the bottom. The lighter particles of the clay may then be run ofi. It is a peculiar characteristic of this clay that the commoner qualities are the more plastic and require less care in handling than the finer grades. None of them are as plastic as the ball clay, however, but they contain very little of the objectionable iron. This clay is used in the pottery to strengthen it against heavy weights and sudden changes of temperature, as well as to increase its...show more

Product details

  • Paperback | 50 pages
  • 189 x 246 x 3mm | 109g
  • Rarebooksclub.com
  • United States
  • English
  • black & white illustrations
  • 1236953142
  • 9781236953148