Hi-Sil T-650 Thixotropic silica PPG Industries Rheology Modifiers / Thickeners >> Mineral >> Synthetic Silica Polyesters ADHESIVE >> Solvent based SEALANT Hi-Sil® Thixotropic Silicas Hi-Sil® T-600 and T-700 are synthetic precipitated silica thixotropes used in a variety of coatings, resins, sealants and adhesive systems as rheology modifiers and anti-sag/suspension aids. Hi-Sil® T-650 Thickener/thixotrope for solvent based coatings, polyester gel coats, resins, adhesives, caulks, sealants, inks. Synthetic, precipitated silica thixotrope. Used as a rheology modifier and an anti-sag/suspension aid in solvent based adhesives, caulks and sealants.