A thickening additive used to control viscosity of epoxy and prevent epoxy runoff in vertical and overhead joints. A very strong filler that creates a smooth mixture, ideal for general bonding and filleting. Our most versatile filler. Often used in combination with other fillers, it can be used to improve strength, abrasion resistance, and consistency of fairing compounds, resulting in a tougher, smoother surface. Color: off-white.