Manufacturers of optical coatings and components

Schott RG series glass is a colloidally colored red/black glass (except RG1000, which is ionically colored; and RG9, which is a mixture of ionically and colloidally colored glass) that transmit infrared radiation and absorb ultraviolet and most visible radiation.  In general, colloidal colorants are highly dependent on secondary heat treatments during manufacture and exhibit variation within any given melt due to temperature gradients during the striking process.

All of the Schott RG series glasses exhibit a tendency to stain and are susceptible to acid etching, except RG1000.   RG830 and RG850 are very susceptible to staining and acid attack.  All RG series glass is relatively impervious to alkali attack.