Indicating silica gel desiccant also name color changed desiccant. When absorbing water, the silica gel bead will turn its original color to another color. Commonly, there are blue, orange and other color indicating silica gel desiccants. Besides we can divide them to with Cobalt and Cobalt free types.
The normal blue silica gel desiccant contains Cobalt chloride, which can change color to pink after water adsorption. We should avoid inhalation and contacting with food because it is poisonous. And the cobalt free blue silica gel desiccant contains Congo red which usual as Acid-base indicator. The original blue will change in the PH value from 3.5 to 5.2, if the state is alkaline, the blue will turn to red, if acid, blue purple.
The cobalt- free orange silica gel desiccant is more environmental friendly (after adsorption, the orange will turn to dark green). The main reason for color changing is the desiccant contains ingredient of Methyl violet which will change color (from orange gradually to dark green) according its PH value between 0.13 to 0.5.
