403 Microfibers Adhesive Filler is a fine fiber blend. Use it to thicken epoxy blended resin/hardener and create a multi-purpose adhesive. Its most popular use is for bonding wood. Epoxy thickened with microfibers has good gap-filling qualities but will still do an excellent job of wetting-out/penetrating into wood fibers. You can blend it into any WEST SYSTEM® 105 Epoxy Resin®/200 Series Hardener combination, G/flex® 650, or G/5® Five-Minute Adhesive.