Westvaco Corporation

Frank T Knapp

Wilfred H Gendron

An envelope and blank structure is disclosed for use with promotional mailings. The envelope includes at least one window opening in its front panel which is normally covered by a sheet of transparent window material. The outer surface of the window material is in turn applied with a non-transparent coating for obscuring a message included within the envelope beneath the window opening. The message may subsequently be revealed without opening the envelope by scratching or rubbing the coating from the window material.

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Chicopee, MA, United States of America

Frank T Knapp