All About Glass

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The Mechanical Press

All About Glass

mechanical press

Making and decorating a piece of glass took a lot of talent, training, and teamwork. In the 1820s, Americans developed a pressing machine that needed only two people with little experience to make it work.

One person brought the hot glass from the furnace to the mold. The second cut off the right amount of glass to drop into the patterned mold which was made either of iron or brass. He then pulled the plunger down to squeeze this hot, soft glass into the mold. A decorated piece came out of the press in a few seconds.

Because contact with a cool mold could produce wrinkles on the surface of the hot glass, mold makers designed patterns with stippled backgrounds (Fig.1). Every square inch of the piece was decorated in order for the wrinkles not to show. Technological improvements (heating the molds to almost red-hot, then dropping in the molten glass) eliminated the chill marks, and patterns became simpler after the 1840s (Fig. 2).

Published on November 30, 2011