It really isn't true that red filters quit being used. Some materials are not sensitive to the broader spectrum of an amber light, making it feasible to use one. The broader spectrum is probably easier for many people to work under. Some manufacturers recommend amber safelights on the strength of improved working conditions even for materials where an amber safelight is marginal. But some materials _are_ sensitive to parts of the amber, or even to the whole visible spectrum, and other types of filter (or even no light at all) must be used. A quick perusal of B&H stock indicates that lots of red safelights are still offered. De