Glauber’s salt (Sodium Sulfate, Glaubersalz, Natrum Sulfat) – Na2SO4 is sodium sulfate. It is an
electrolyte, sulfuric acid salt. It is widely used in dyeing textile materials: in the case of dyeing
cellulosic fibers with direct and active dyes it is used as a dye activator that increases the
substantivity and sorption of dyes. In the case of dyeing wool with acid dyes, Glauber's salt is
used as a retarding agent (leveling agent) for dyeing. In the first case, Na2SO4 is dissociated into
the ions and reduces the electric barrier between the negatively charged fiber and dye ions. In the
second case, Na2SO4 is dissociated into the ions and competes with the dye anions for sorption
on the active NH3+ groups of the wool (acidic medium).