Borosilicate glass has a very low coefficient of thermal expansion, about one-third that of ordinary glass. This will reduce the effects of stress due to temperature gradients, resulting in stronger fracture resistance. Because of its very small shape deviation, this makes it an indispensable material for telescopes and reflectors. It can also be used to handle highly radioactive nuclear waste.
The borosilicate glass begins to soften at approximately 821 °C (1510 °F), at which temperature the Model 7740 has a high borosilicate viscosity of 107.6 weights.
Borosilicate glass is denser than ordinary glass.
Although more and more resistant to thermal shock than other types of glass, borosilicate glass can still break due to rapid or uneven temperature changes. When broken, borosilicate glass cracks tend to be rather large, rather than crushed (it will unit rather than split).
Optically, borosilicate glass has low dispersion (about 65 Abe number of crown glasses) and relatively low refractive index