monophosphates: Sodium monophosphates are manufactured from furnace and (post-purified) wet-process acid and sodium carbonate or .

Sodium hydroxide has to be used in the manufacture of trisodium phosphates, since sodium carbonate is not alkaline enough. The salts, which can be anhydrous or hydrated, are produced by conventional techniques. In the dehydration of both hydrogen phosphates particular temperatures must be maintained to avoid condensation to di- or poly-phosphates.

Sodium di- and poly-phosphates: Diphosphates, di-sodium dihydrogen diphosphates and tetrasodium diphosphates are industrially produced by heating sodium hydrogen phosphates.

Both reaction time and temperature must be limited during production to prevent further condensation to higher molecular weight phosphates.

Condensation can be carried out in rotary kilns or in spray towers.

Polyphosphates: Pentasodium triphosphate is obtained by the condensation of and disodium hydrogen phosphate in a 1 :2 ratio:

Industrially, a phosphoric acid solution is used which is neutralized with the appropriate quantity of sodium hydroxide or sodium carbonate. Condensation of the monophosphate solution is carried out in one or more stages in spray towers or rotary kilns.

The anhydrous pentasodium tripolyphosphate produced has a high and low temperature modification, which react at different rates with water to the hexahydrate. The proportions of the two modifications is dependent upon the temperature at which condensation takes place.

Higher molecular weight polyphosphates: Oligomeric polyphosphates with n = 2 (tetraphosphate) to n = ca. 25 (Graham's salt) can be obtained upon condensation of disodium hydrogen phosphate with sodium dihydrogen phosphate by increasing the proportion of sodium dihydrogen phosphate in the mixture.

The manufacture of these glassy polyphosphates or melt phosphates occurs as follows:

Sodium dihydrogen phosphate is converted by way of disodium dihydrogen diphosphate (see above) to the high molecular weight Maddrell's salt (n > 1000) upon heating at temperatures above 250°C.

Due to the high corrosivity of melts containing sodium polyphosphate, it is produced in vats lined with zirconium silicate bricks. When the reaction is complete, the melt is quenched on cooling rollers. In a process developed by Hoechst AG (FRG), the polymeric phosphates are obtained by phosphorus combustion with air in the presence of sodium hydroxide in a graphite-lined tower. The total energy for the process is provided by the combustion of the phosphorus.