Aerogel is a synthetic, porous, ultra-light material derived from a gel, in which the liquid component of the gel has been replaced with a gas. The result is a solid with extremely low density and low thermal conductivity. Nicknames include ‘frozen smoke, solid smoke, solid air, or blue smoke,’ owing to its translucent nature and the way light scatters in the material.

Aerogel first became known as the insulation material used in the Pathfinder research vehicle that travelled across the surface of Mars. Since that time, research has been carried on into the use of aerogel for ’terrestrial’ applications, e.g. as insulation material for houses and other buildings.

Aerogels are irregularly shaped particles, ranging from about 0.5mm to 4.0mm in size depending on grade. Their primary use is in daylighting applications, where visible light is required to pass through a daylighting unit which still maintains excellent thermal insulation.

Aerogel uses a combination of mineral acid and beach sand that has been dissolved in a liquid known as ’water glass’ (a solution of sodium silicate). When this liquid is combined with an acid, it coalesces to form a silica gel. The pores of the gel contain water, but the gel is low in solids and is capable of producing a low-density dry gel. When the liquid is extracted from the gel, e.g. by evaporation, it shrinks and collapses, just like a kitchen sponge.