Item Industry Grade Fine Grade Appearance white crystal granule or powder White crystal powder Assay ( dry ) 98 % min 99%min Assay ( wet ) 75 % min 84%min Moisture 23-25 % 16¡À0.5% Free acid 0.65 % max 0.65% max Chlorine 0.20 % max 0.20 % max Melting point 102-105 ¡æ 102-105 ¡æ