The Humidity Indicator Card provides a visual record for monitoring the relative humidity inside sealed containers and in the atmosphere. The indicator elements on the cards are nine separate small squares in a vertical line. Each one responds to humidity changes in 10% increments. The square turns color (pink to blue) to indicate the change in relative humidity. The accuracy of the card is 5% in each application. The indicators are water soluble and the card must not be placed in direct contact with water, steam or metals. High temperatures will also affect the accuracy of the humidity readings and in this case the humidity indicated will be lower than the actual relative humidity. The indicators are reversible, but we recommend that the cards be kept in a sealed container until use. The card is rectangular, 1 1/2 inches by 4 inches. The edges of the card can be cut away leaving just the indicator strip, 3/4" by 2 3/4".

Sold in packs of 10 or 25.