Humidity Indicator Card use color changing to judge humidity changing. When it is dry, the dot(s) on Humidity Indicator Card is blue. If the dot(s) changes from blue to pink, it means the humidity inside the package reaches or exceeds the relative humidity which the dot(s) corresponding to.
The color changing of Humidity Indicator Card is reversible. Humidity exceeds the humidity corresponding to the dot(s), the color change from blue to pink. If humidity is lower than the humidity corresponding to the dot(s), the pinked Humidity Indicator Card can change back to blue. But it need more time from pink to blue and need enough desiccant to make Humidity Indicator Card resume blue.
We are professional in producing Cobalt-Free Humidity Indicator Card manufacturer