Allochroic silica is the addition of silica and inorganic salts with crystal water, small amounts of silicon dichloride, such as cobalt salts. When it is dry and loses the crystal water, it is blue. When it absorbs water and obtains the crystal water, it is pink. Allochroic silica can be recycled. When the color changes, it can be baked in a dry box to return to the anhydrous state for continuous use. The blue silica points can be divided into blue glue indicator, allochroic silica and blue glue. The appearance is blue or light blue glass particles.
It is usually used as an indicator. Its characteristic is that it will turn red after absorbing moisture. When it is not hygroscopic, the particles are blue. When it is wet, the colloidal particles absorb moisture and gradually become light blue. When it continues to absorb moisture, it will turn pink to indicate that it needs to be replaced with a new silica for continuous use. When it is used in conjunction with ordinary silica desiccants, it can indicate the degree of moisture absorption of desiccants and the relative humidity of the environment.
It is mainly used for moisture absorption and rust prevention of instruments and meters under closed conditions. It can be widely applied in aviation, military, power industry, civil and other moisture-proof function and humidity indication.