from approximately 20 seconds to approximately 20 minutes depending on the temperature in the oven and the fabric temperature in step 102 a thp based compound is applied to the fabric examples of suitable thp based compounds include but are not limited to tetrakis hydroxymethyl phosphonium sulfate urea u201c thps urea u201d and tetrakis hydroxymethyl phosphonium chloride urea u201c thpc urea u201d thps urea and thpc urea are fr compounds the thp based compound is combined with water to form a thp based aqueous solution that can be neutralized to a ph in the range of approximately 5 0 to approximately 7 0 using approximately 5 caustic naoh or using one or more other suitable alkali agents note this ph range is suitable for good fabric strength and fr efficiency but the process can also run at an even wider range of phs such as phs ranging from approximately 3 0 to approximately 8 0 the thp based aqueous solution is applied to the fabric and the fabric is padded as described above in step 101 after the fabric is treated with the thp based compound the fabric is dried in step 103 the fabric is ammoniated by placing the fabric in an ammonia chamber in order to form a flame retardant polymer containing phosphorous 3 for example the fabric can be ammoniated by spraying the fabric with or exposing the fabric to an anhydrous ammonia gas in step 104 the fabric is oxidized washed and framed the fabric can be oxidized by placing the fabric in an aqueous solution composed of approximately 10 peroxide the oxidation process may occur in the same chamber as the ammonia chamber or in a separate chamber other suitable oxidizing agents include but are not limited to sodium percarbonate or.