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A humidity indicator will detect the percentage of relative humidity inside a package. Rosewood supplies indicators in both clock and card format. Screw-in indicator clocks can be attached to a barrier foil bag to create an airtight seal and allow continual monitoring of the relative humidity conditions inside the bag. This device is ideal for long-term storage applications.

Indicator cards can be placed in clear polythene windows. Moisture sensitive spots on the card change colour in response to levels of relative humidity inside the barrier foil bag. A blue colouration on the card indicates that it is below 40%.