d7e42f72_ES__INC____Roofing_Terminology__VALLEY
Any of various processes by which natural or synthetic rubber or other polymeric materials may be cured or otherwise treated (i.e. exposed to chemicals, heat or pressure) to render them non thermoplastic, and which improve their elastic and physical properties. [VALLEY] 
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ARMKO INDUSTRIES, INC. - Roofing Terminology
VALLEY