How to validate for silica gel seft indication?
Typical specification of silica gel beads with self colour indicator is as follows,
Appearance - Dark blue crystals / beads
Solubility in water - Insoluble in water
Loss on drying (at 150 deg. C) - Approx 2%
Moisture absorption capacity - Min. 27% at 80% Relative Humidity for 24 hours
Mesh size - 5 to 8 #
Change of colour from blue to pink indicates moisture absorption by Silica gel crystals which can be determined by Karl Fischer titration method.