Humidity Indicator Cards

Humidity indicator cards provide a simple, reliable, visual indication of the relative humidity within a sealed environment. As the humidity increases, the spots on the card change from blue (dry), through to lavender, to pink (humid).

While they are not precision indicators, they are useful for quickly determining if an environment has exceeded a particular humidity threshold. For example, if all of the spots are pink on a 30-50% card, then the humidity in that container has exceeded 50% RH. If all the spots are blue, then the humidity is still 30% or below.

It is recommended that the card is not placed in direct contact with metal objects as the chemical indicator in the card may cause corrosion of some metals.