403 Microfibers Adhesive Filler, is a fine fiber blend. Use it to thicken epoxy blended resin/hardener and create a multi-purpose adhesive. It’s 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 Resin/20X Hardener combination, G/flex Epoxy 650, or G/5 Five-Minute Adhesive. Blended with epoxy, it will cure to an off-white color.
VIDEO: A Guide to Adding Filler to Epoxy
Because epoxy can be thickened with high-density fillers into a non-slumping consistency it can bridge large gaps in wood joints, without loss of strength, thus saving a great deal of time labor otherwise needed to create a strong joint.
Read about how master strip plank boatbuilder Ted Moores used WEST SYSTEM 403 filler while strip planking the electric launch Sparks. As he explains, The key to a joint that did not fail was to saturate the end grain with mixed un-thickened epoxy until it stayed shiny, followed by a thin coat of epoxy thickened with 403 Microfibers Adhesive Filler.