Kyodo Printing Co Ltd, Japan has developed for the first time HumiJudge, a humidity indicator that uses no cobalt chloride. Reacting to the humidity in the ambient environment, the indicator turns blue at low humidity and red at high humidity. Kyodo Printing will propose the product to electronics and automobile component manufacturers for whom humidity control is necessary.The HumiJudge is free from heavy and rare metal and do not use the RoHS restricted 6 hazardous substances. With high visibility, same hue alteration as cobalt-based indicators, the humidity indicator HumiJudge can be disposed easily as normal waste paper. The hue alteration configurability is in a range between 5% and 30% RH (relative humidity).
Most of current humidity indicator cards made of paper use heavy metal cobalt compound (cobalt chloride). Cobalt compound, however, is specified as a carcinogenic substance by the International Agency for Research on Cancer (IARC), American Conference of Governmental Industrial Hygienists (ACGIH) and Japan Society Occupational Health, among other organizations, and therefore recently the need for replacement of cobalt has been increasing, according to the company.
