This is a vitreous volcanic rock that contains molecules of water of crystallisation. This mineral, crushed to a default grade, is heated at 1,200°C in special furnaces. At this temperature, the occluded water turns into steam and acts as an expanding agent until a light grain is formed, consisting of closed, empty microcells, thereby multiplying its volume up to 20 times. This is a physical process only.

The distinguishing feature which sets perlite apart from other volcanic glasses is that when heated to a suitable point in its softening range, it expands from four to twenty times its original volume.

This expansion is due to the presence of two to six percent combined water in the crude perlite rock. When quickly heated to above 1600°F (871°C), the crude rock pops in a manner similar to popcorn as the combined water vaporizes and creates countless tiny bubbles which account for the amazing light weight and other exceptional physical properties of expanded perlite.

This expansion process also creates one of perlite’s most distinguishing characteristics: its white color. While the crude rock may range from transparent light gray to glossy black, the color of expanded perlite ranges from snowy white to grayish white.

Expanded perlite can be manufactured to weigh as little as 2 pounds per cubic foot (32kg/m3) making it adaptable for numerous applications. Since perlite is a form of natural glass, it is classified as chemically inert and has a pH of approximately 7.

Perlite, once its volume has increased, keeps all of its initial mineral properties such as: Non- tóxic. It does not contain or emit any toxic or harmful substances.

Imputrescible – It does not contain any organic substances, it is a mineral.

Incombustible – It does not burn, it avoids fire propagation, it only melts at 1,000°C and above: it is a fireproof product.

Chemically inert – It is a natural glass (aluminium, potassium and sodium silicate). It stabilises over time.

Light – Expanded perlite has a low density, between 50 and 125 Kg/m3, making it an excellent material for insulation and soundproofing.

Economical – If we consider the cost-volume-insulation capacity ratio, expanded perlite is the most economical insulating material around at present. It is nature’s best insulator.

Due to its closed, empty microcells, perlite eliminates any heat exchange through conduction and radiation. The perlite grains also immobilise any air present, thus avoiding the transmission of heat through convection.