Cobalt-containing humidity cards, while visually displaying humidity changes, pose environmental concerns. Their working principle involves cobalt chloride absorbing moisture and changing color; it is blue when dry and turns pink as humidity increases, corresponding to different humidity values. This process is reversible; the color change from red to blue requires drying conditions. However, since the EU classified cobalt chloride as a Group 2 carcinogen in 2004, there are strict restrictions on cobalt-containing products, and products exported to the EU must comply. Currently, humidity cards containing cobalt chloride are about to be banned.
Cobalt-free humidity indicator cards, as a more environmentally friendly option, quickly determine ambient humidity through color changes; the color changes from dry to hygroscopic, visually indicating the desiccant's effectiveness. These cards have become the mainstream in the market due to their convenience and affordability.
In response to increasingly stringent regulations, TOPCOD has established a humidity card division and developed a new generation of environmentally friendly humidity indicator cards, including Type I, Type II, and Type III. These cards feature upgraded production processes, high daily output, compliance with the EU RoHS directive, and have passed CTI and SGS testing. The new humidity cards exhibit distinct color variations, superior craftsmanship, and greater ease of use, meeting modern environmental standards.