Product thaw indicator - includes diffusion agent which above given temp. can diffuse through wick to indicator window

摘要

A device for indicating whether or not a product has thawed and then been refrozen includes a housing which is securable in good thermal contact to the exterior of a package containing a frozen product. The walls of the housing insulate it from the environment while at the same time assuring good thermal contact with the product. A closed membrane within the housing contains a diffusion agent, and a wick extends from the membrane to transparent windows in the wall of the housing. A dam extends across the wick to separate the closed membrane from the windows to control diffusion of the diffusion agent through the wick.