AEROSIL® fumed silica can prevent or at least slow down the settling of fillers or pigments in heavily loaded adhesive and sealants. After long time storage times, some settling may be observed however in many cases with AEROSIL® fumed silica sedimentation is soft and can be easily resuspended. This effect is mainly due to the reduced mobility of the pigments/fillers in the liquid system and mainly caused by a yield value and less on the viscosity increase.
The picture shows, that the hydrophobic grades AEROSIL® R 202 and AEROSIL® R 805 hold the calcium carbonate in suspension after 90 days of storage time at 50 °C. The test with the hydrophilic silica AEROSIL® 300 and 20 parts chalk (left glass cylinder) shows after 28 days of storage time a significant sedimentation of the calcium carbonate. The white glass cylinders with AEROSIL® 300, AEROSIL® R 202 and AEROSIL® R 805 and epoxy resins do not change during the storage.