A novel flame retardant and fire extinguishing product for preventing and fighting fires in solid materials is disclosed herein. The product is thixotropic and non-toxic, and comprises water, one or more flame retardants, one or more stabilizers, and one or more preservatives. In some embodiments, the product further comprises one or more thickeners, one or more binders, one or more fining agents, one or more firming agents, one or more water retention agents, one or more water-soluble fluoropolymers or other water-soluble polymers with similar properties, one or more detergents, and/or one or more surfactants. The product may be used as a flame retardant to prevent fires and in active firefighting. The product may be biodegradable in a natural environment, may be readily cleaned off equipment and materials using water, and may also provide other features which render it safe for the environment as compared to other commonly used products in fire prevention and firefighting.