They can be set at room temperature in 5 to 15 minutes. The shrinkage problem has been eliminated ; units can be handled at high production rates by unskilled workmen without fear of damage.
In addition, the materials absorb no moisture from the surrounding atmosphere, guaranteeing that the electrical characteristics of the embedded equipment will remain <unimpaired.
The Polyform G series consists of three formulas: No. 107, slight shrinkage, for ease of mold extraction; No. 622, no shrinkage, generally used for potting transformers in cans; and No. 1230, slight expansion, used to embed complete units and adhere to walls of cavity.
According to Mr. G. G. Forman, research director and specialist in metalto-plastic combinations, the new materials take the potting process out of the "mudpie" stage and into the realm of competitive mass production.
Utilizing casting methods made possible with these materials, components of varying size from subminiature radio tubes up to large bus bar units can be successfully encapsulated.
Because viscosity of the new materials can be adjusted over a wide range, from waterlike up to a thick tarry syrup, the entire electrical industry is interested.
In small transformers the new materials replace conventional potting materials including varnishes and waxes. Used with vacuum, a low viscosity formulation penetrates every part of the transformer thoroughly, and achieves complete hermetical sealing.