Dihua ‘s glass is a borosilicate glass type 3.3 as specified in international standard ISO 3585,whose chemical resistance of glass is more extensive than that of all other known materials.Borosilicate glass is highly resistant to water,acids,salt solutions,organic substances and also halogens such as chlorince and bromine.It also has relatively good resistance to alkaline solutions.Only hydrofluoric acid,concentrated phosphoric acid and strong alkaline solutions cause appreciable surface removal of the glass at higher temperature.This kind of glass is manufactured from natural raw materials(sand,calcium carbonate and sodium carbonate) and doesn’t contain any materials which could be released and constitute a hazard to man or the environment .Glass can be reused several times and disposed of without difficulties. Silicon content >80 % Strain temperature 520 ℃ Annealing temperature 560 ℃ Softening temperature 820 ℃ Refractive index 1.47 Light transmittance (2mm) 92 % Elastic Modulus 76KNmm - 2 Tensile strength 40- 120Nmm - 2 Glass Stress Optical Constants 3.8 * 10-6mm 2 /No Processing temperature （ 104dpas ） 1220 ℃ Linear expansion coefficient（ 20-300 ℃） 3.3 * 10-6 K - 1 Density （20 ℃） 2.23gcm - 1 Specific heat 0.9jg - 1K- 1 Thermal Conductivity 1.2Wm - 1K- 1 Water resistance (International Organization for Standardization 719) Level 1 Acid resistance (International Organization for Standardization 195) Level 1 Alkali resistance (International Organization for Standardization 695)