Cooling moldability

Impression Waxes. Impression waxes include those waxes used to obtain a negative cast of the mouth stmcture (impression waxes), waxes used to estabhsh tooth articulation (bite-registration waxes), and waxes used to detect tooth interference and high spots or improper fit of denture bases (disclosing waxes). They must be plastic and moldable at mouth temperatures, and chill to a stiU nonplastic mass upon cooling within a few degrees below mouth temperature. 

The Augusta facility produced plastics, including Amodel, a hard but moldable high-performance nylon. Amodel is manufactured by passing a solution of diamines and dicarboxylic acids through a series of reactors. The reaction is completed in an extruder, and the material is then formed and cooled into solid pellets. 

It has long been appreciated by our ancestors that some muds, when wet, were easily moldable into shapes that upon heating became rigid. The formation of useful articles from fired mud must constitute one of the oldest and more fascinating of human endeavors. Fired-clay articles have been traced to the dawn of civilization. The usefulness of these new materials, however, was limited by the fact that when fired, they were porous and thus could not be used to carry liquids. Later the serendipitous discovery was made that when heated and slowly cooled, some sands tended to form a transparent, water-impervious solid, known today as glass. From that point on, it was simply a matter of time before glazes were developed that rendered clay objects not only watertight, but also quite beautiful. 

THERMOPLASTIC A material that becomes soft and moldable when heated, then hardens when it is cooled. 

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