Fumed Silica

Fumed silica, often known by trade names Cabosil and Aerosil, or as colloidal silica, is a thixotropic flow modifier. This fine white powder is used to thicken adhesive and fairing mixes and reduce their flow on vertical surfaces. Relatively small quantities added to a resin mix containing glass bubbles will give non-sag properties. Silica is also used with micro-fibres to produce high strength, non-sagging structural adhesive. The inclusion of fumed silica will increase the hardness of the resulting mix, making it more difficult to sand. For this reason silica is usually added in the minimum quantities to any mix for which sanding is anticipated.