A process for preparing a flame retardant composition, the process comprising: adding to a container at least one flame retardant salt, a nitrogen-containing compound, and optionally water; and mixing the contents of the container to give a dispersed mixture or dissolved solution comprising the flame retardant composition; wherein the at least one flame retardant salt comprises an ammonium salt of phosphoric acid; wherein the ammonium salt of phosphoric acid comprises water soluble ammonium polyphosphate (APP); wherein the water soluble ammonium polyphosphate has a total nitrogen as N from about 5 to about 15 weight percent, and a total phosphorus as P2O5 from about 30 to about 40 weight percent, based on the total weight of the ammonium polyphosphate (APP).