Self-indicating silica gels will adsorb moisture in exactly the same way as standard non-indicating (white) silica gel, but they will literally indicate when they are becoming saturated by changing their colour.

This is useful in two ways. Firstly, a silica gel sachet or breather unit where the gel has changed colour, gives an immediate warning that it should be replaced.

Secondly, if regenerating the silica gel, the self-indicating grade will be ready for reuse, when its original colour has returned.

silica gels uses a small concentration (between 0.5 and 1.0% weight for weight) of moisture sensitive cobalt chloride indicator, which gives a blue silica gel. This changes to pink as it adsorbs moisture and becomes saturated, returning to blue as it is regenerated.