West System Filler Colloidal Silica 6 406
Great for general bonding and West System's most versatile filler, 406 is a thickening additive that keeps your epoxy from dribbling down off vertical joints. It creates a smooth mixture and dries to an off-white colour. Being an adhesive filler, it is difficult to sand after curing and is used mainly for bonding rather than cosmetic purposes. People often use other fillers in combination with this one; it's good for toughening up fairing compounds.