SP Microfibres are very fine wood-cellulose fibres commonly used to create structural adhesives for bonding both wood and grp.
Because any low viscosity resin system is readily absorbed into a porous surface such as wood, an unfilled adhesive may tend to give a ‘dry joint’. With their absorbent properties, microfibres can retain a significant quantity of adhesive within a joint and limit resin absorption into the surrounding surface, thus ensuring an adequate resin supply for adhesion. Where the strongest bond is required, e.g. timber scarf joints, microfibres should always be used in preference to hollow sphere-types of filler.
For bonding parallel to the grain with lower density, lower strength timbers, such as cedar or obeche, a microballoon mix is often adequate, and is of lower density.