Abstract: A marking element is disclosed for indicating whether a predefined temperature condition has been maintained. The marking element has a first material capable of flowing when exposed to a temperature above a predefined temperature separated from an absorbent second material by a heat-disruptable barrier layer. The first and second materials are such that when the heat-disruptable barrier layer is punctured and the predefined temperature is exceeded, the first material flows into the absorbent second material to produce a detectable change. The heat-disruptable barrier layer is formed of a heat-disruptable material associated with an element capable of being inductively heated by electromagnetic energy to effect disruption of such layer, thereby activating the marking element.

Abstract: A material such as fabric, plastic, leather or paper incorporates retroreflective properties which result from the application of metal coated microbeads. Methods for the application of microbeads to various surfaces as well as the formulation of printing inks containing microheads are disclosed.