Humidity Indicator Card

This humidity indicator card is a useful tool to help protect sensitive items from exposure to too much moisture in the air. It works by taking advantage of the color-changing properties of the chemical cobalt dichloride (CoCl2). When dry, or anhydrous, the CoCl2 circles will appear bright blue. When exposed to moisture, they will gradually turn pink. By cleverly creating several circles of various concentrations, a measurement of relative humidity exposure can be determined, rather than a simple yes or no. Card can be reset and reused by placing it in a dry container (such as a sealed bag with desiccant or rice) for 24 hours. 1.75" x 4.56"