Sodium silicate solutions were dried to form water containing amorphous solids. "Synthetic" sols were also prepared by dispensing silica colloids in NaOH solution. The size of the colloids was varied by using different grades of pyrogenic silica as precursors. The resulting sodium silicate liquids were dried at temperatures between 40-120 deg C under controlled climatic conditions. The residual water contents were determined gravimetrically. A gradual solidification of the solutions during drying is observed. Under appropriate drying conditions, amorphous materials are obtained. The process of solidification is interpreted as immobilisation of the colloids due to the extraction of water, thus reducing the distances between the colloidal particles. A correlation between structural parameters and drying conditions is discussed.
