Color-changing silica gel is also divided into several categories.

Name Blue Glue Indicator, Color Change

Color-changing silica gel) (low humidity-high humidity) blue-purple-light purplish red

(Light blue-purplish red-light red) Indicator main components: Cobalt chloride process is the most mature, the lowest cost, characteristics and application: it is generally required to be used in occasions.

Orange glue (silica gel with orange turning green,

Cobalt-free color-changing silica gel) orange-yellow-green-dark green

(Light orange-light yellow green-green) Indicator main component: ammonium ferrous sulfate.

Characteristics and application of copper chloride: cobalt-free, relatively safe, replacing blue glue.

Orange glue (orange white silica gel,

New cobalt-free color-changing silica gel) Orange-light orange-colorless indicator Main component: ammonium ferric sulfate.

Characteristics and application of ammonium ferrous sulfate: it does not contain harmful metal elements such as cobalt and copper.

European and American countries are widely used.