Aerogels are materials that are very similar to normal gels, except for the key detail that the liquid component has been replaced with a gas! Since liquids were such a large component of gels by weight, Aerogels are very lightweight. This type of material is translucent and has been given nicknames like “solid smoke” or “solid air.” It is produced by extracting the liquid component from a gel using a process called supercritical drying, which allows the liquid to be evaporated away without causing the solid network of chemical bonds to collapse. Aerogels have been produced from a variety of materials including alumina, silica, chromia, and tin dioxide.