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"