| 摘要 |
An apparatus for invalidating trading stamps of the type that are placed in disposable paper books for redemption, and the stamps prior to distribution to customers having an insignia defined on the printed surface thereof by a temperature sensitive ink. The apparatus is equally adapted for use in invalidating certificates having redemption value, when the certificates have insignias defined thereon in temperature sensitive ink. The books of stamps or certificates of the above description are received at a customer servicing structure in a redemption center, which structure has a movable locked redeemed stamp book and certificate receiver associated therewith. The receiver when filled with redeemed stamp books or certificates is moved to an electrically operated device, where the stamps or certificates therein are subjected to a predetermined temperature substantially different from that of the ambient temperature for not less than a predetermined length of time, to permanently change the temperature sensitive ink that defines said insignias from a first color to a second color. The second color is one that has a fixed meaning to personnel in the redemption center and indicates that the stamps or certificates have been redeemed. After the stamp containing books or certificates have been so temperature treated they are valueless, and may be freely transported to an area remote from the redemption service center for subsequent delivery as raw stock to a paper mill.
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