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.


  • 3 spot reversible humidity indicator (30%, 40%, 50% RH)
  • Spots change from blue (dry) to pink (humid).
  • Designed for use within sealed environments.
  • Complies with Mil-I8835 and Mil STD-2073-1
  • NSN:6685-00-752-8240
Model # MS20003-2
Brand Clariant®
NSN # 6685-00-752-8240
Complies With Mil-I8835 and Mil STD-2073-1
Type Reversible Blue - Pink
Dimensions 80 x 50mm
RH Levels 30% 40% 50%
Carton Quantity 125 cards per tin
Shelf Life 3+ years in original packaging