Use this filler when a low density, sandable, paint-ready surface is required, such as fairing compounds. It cures to a sandable solid and when used in conjunction with Colloidal Silica can be pulled or drawn to a feather edge. Add an equal amount of silica by volume to the mixed epoxy and then thicken the rest of the way with Phenolic Micro Balloons. The liquid sheen should just go away when the material has been mixed correctly. MAS recommends using medium hardener and our FLAG resin with the Phenolic Micro Balloons mix.