Abstract: A compound is provided having the means of intumescence at temperatures above 195° C. to 220° C. The compound is an intumescent powder defined by the molar ratios (2.20 to 3.70) SiO2/(0.20 to 0.35) Li2O: (0.65 to 0.80)(Na2O+K2O) where the coefficients of Li2O and of (Na2O+K2O) total 1.00 and thermoplastic material having a plastic state at less than 195° C. If the thermoplastic contains a halogen, as does Polyvinyl Chloride (PVC) the halogen acts as a flame retardant in the event of combustion and prevents complete burning of the plastic. If there is as filler mixed with the compound which is endothermic this assists with the fire retardant effect of the compound.

Abstract: An intumescent powder where the molar ratio of SiO2 to Li2O+Na2O+K2O is between 2.20 to 3.70 to 1.00 and the molar ratio of Li2O to Li2O+Na2O+K2O is 0.20 to 0.35 has an intumescent point of 195° C. or higher and thus will not prematurely intumesce if mixed with another material at temperatures below 195° C. The powder as used is usually dried to 8-12% by weight to moisture for most purposes is ground to 50 to −500 microns. Preferred methods of manufacture comprise taking a source of lithium hydroxide or lithium silicate and a source of sodium silicate to create a powder with ratios as outlined above.