... purity caustic soda pearl is the upgrade product of the solid caustic soda pearl.Testing result:NaOH: 99.4%, Na2CO3:0.27 ... %, NaCl:0.010%, Fe2O3:0.002%Testing result of the Food Grade:NaOH: 99.1%, Na2CO3:0.56%, As ... making, printing, dyeing, soap; the original dye, the dissolving agent of the dye which is not soluble in azote; medicine, food ...