Vermiculite is the name given to a group of hydrated laminar aluminium-iron-magnesium silicates. Raw vermiculite consists of thin, flat flakes containing microscopic layers of water.
When vermiculite is exfoliated thermally, the microscopic layers of water are explosively removed and the flakes expand to worm-like, light weight particles. Chemical exfoliation also leads to expansion but the result is individual platelets with a high aspect ratio that are freely suspended in water.
Vermiculite is inert and does not react chemically or burn. When the flammable substrate is subjected to heat, the Micashield layer inhibits access of oxygen to the combustible material in a similar manner to a char layer.
This physical barrier acts as a suppressant to smoke and to re-ignition. It reduces the temperature evolution of the substrate. It accumulates at the surface of the substrate and forms a barrier to mass and energy transfer. Micashield reduces the rate of flame spread and heat release.
It can be combined with many different materials where it is encapsulated, or encapsulates, rather than being chemically bound.
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