... ( 2ZnO.3B2O33.5H2O)Excellent gradeFirst gradeWhiteness9995Surface water % ≤0.51.0Particle size, um3-53-5ZnO, %37.0-40.0B2O3 , %45.0-48 ... non-toxicity, slight solubility in water, good thermal stability, fine particle size, low specific gravity, great free-flowing etc. As one high ...