TEMPERATURE-SENSITIVE PRODUCT BEARING A REPRESENTATION

摘要

There is disclosed a product, such as a competition card (10) or greetings card, bearing an initially hidden representation. The product comprises a substrate carrying a temperature sensitive first element (14) and a temperature stable second element (16). At ambient temperatures the first and second elements (14, 16) combine to obscure the representation, however at a higher temperature the appearance of the temperature sensitive element (14) changes to reveal the representation.