Abstract: The invention concerns the production and use of thickened synthetic amorphous silica in water as a fire extinguishing and protection agent in which the water is mixed with 1% to 9% by weight of fumed silica, and the resulting thin fluid suspension is rapidly thickened with mixing and shearing by the addition of from 0.003% to about 0.5% by weight of an additive selected from the group consisting of polyethylene glycols, polypropylene glycols, and their derivatives thereof, wherein the additive has a molar mass between 700 and 600,000.