... dyeing, soap; the original dye, the dissolving agent of the dye which is not soluble in azote; medicine ... . 2. Special feature: High purity (the content of NaOH can reach 99%), even particles, few impurity, ... of the heavy metal and other impurity, we take the 50% ionic membrane liquid caustic soda pearl as material, every part of ... Na2CO3:0.56%, As :<0.0003%, Heavy metal :<0.002% Pb:0.0003%, Hg:0.000005%