Color changing device for time indicating label and methods of making and using the same

The present invention relates to the present invention relates to a time indicating label comprising (a) a label substrate having a first and second surface, (b) an acid-base indicator composition, and (c) an activator composition, wherein one of (b) or (c) are on the first surface of the substrate and wherein (b) and (c) when brought in contact remain adhered. The label may have a pressure sensitive adhesive on the second surface of the label. The invention further relates to a method of using the time-temperature indicating label. The labels provide an effective means for determine the safety of frozen foods. The labels also provide a means of providing security by providing name badges that are time sensitive and may not be reused. The name badges provide a means to monitor the length of a visitor's time and prevents reusing the name badge.