West System 409 Microsphere Blend
A pure white, hollow glass bubble-based, low density filler designed for filling and fairing of fibreglass. When the filler is mixed with WEST SYSTEM® epoxy at a ratio of 10% to 25% by weight, it creates a smooth creamy paste for filling and fairing over glass fibre repairs.
The cured epoxy/filler is very easy to sand. Being white in colour the cured epoxy filler mix will be hidden easily behind paint or polyester gelcoat, but must be protected by further coats of epoxy if used below the waterline.