West System 407 Low-Density Filler

West System's 407 Low-Density Filler is the fairing filler of the West range: a microballoon blend that mixes into 105 epoxy to make an easy-sanding, low-density fairing putty. It cures to a dark red-brown, shapes cleanly with a fairing board, and holds enough strength for faired surfaces above or below the waterline once sealed. 407 or 410? Both sand easily. 410 Microlight is lighter and the easiest sanding of the two, but West limits it to areas out of the water and away from high load. 407 gives up a little sanding speed for real strength, which makes it the pick for hull-side fairing, below-waterline work, and anywhere the faired surface takes abuse. Mixing it Wet out the surface with mixed epoxy first, then thicken the batch with 407 to a peanut-butter consistency for fairing or a bit looser for skim coats. Spread, let it cure, and knock it down with 80 grit before finishing. Our fairing filler calculator sizes the batch for you. The house-brand route Our Phenolic Microballoons are the same class of filler at a fraction of the price per quart, and our pre-blended Fairing Compound adds the anti-sag silica for you. The Compare section below puts them side by side.