... , spraying can be 3. Non- pollution 4.With SGS 1.Application fieldProtection of marble, granite, sandstone, ancient architecture, artifacts ... 0.995 or 1.015Refractive index(25 degree ): 1.390~1.410High hydrogen content( percent sign ,m/m): 1.56 or 1.58Low hydrogen content ... (percent sign,m/m): 0.1~1 ...