As a rule, use higher-density fillers when bonding higher-density materials such as hardwoods and metals. Any of the adhesive fillers are suitable for most bonding situations. Your choice of a filler for general use may be based on the handling characteristics you prefer. Fillers may also be blended to create mixtures with intermediate characteristics.Adhesive Fillers vs. Fairing FillersFillers are used to thicken the basic resin/hardener mixture for specific applications. Each filler possesses a unique set of physical characteristics, but they can be generally categorized as either Adhesive (high-density) or Fairing (low-density).Adhesive filler mixtures cure to a strong, hard-to-sand plastic useful in structural applications like bonding, filleting and hardware bonding.403 Microfibers, a fine fiber blend, is used as a thickening additive with resin/hardener to create a multi-purpose adhesive, especially for bonding wood. Epoxy thickened with microfibers has good gap-filling qualities while retaining excellent wetting/penetrating capability. All West System products are manufactured under a Quality Management System that conforms to BS EN ISO 9001:2000. As a result West System epoxy is a marine epoxy of the highest quality; to the extent that it has been approved by the Lloyds Register of Shipping for the last 20 years.