Aerogel holds 15 entries in the Guinness Book of Records, more than any other material. It is the lightest solid in existence according to the record book. Henceforth, may be the most unique material on the earth.Aerogels have extremely high surface area as well as porosity. These unique properties are being used for thermal and acoustic insulation. Therefore, sometimes called "frozen smoke". This material is produced by the supercritical drying or ambient pressure drying of liquid gels. The most common type is silica aerogel. In this context sol-gel processing of water glass (sodium silicate) and alkooxide based silica aerogels is described. The silica gels are dried at ambient pressure to reduce final cost of the aerogel. Their physical properties are studied. Это и многое другое вы найдете в книге Ambient pressure dried silica aerogels and their properties (Jyoti Gurav)