UV Blocking Glass acts as a mirror with regard to ultraviolet light wavelengths (400nm and shorter). UV rays are one of the most significant sources of degradation in museum artwork. As such it is a problem that has prompted much consideration. Since artwork is intended to be seen, it is important that any solution to this problem not obscure visible light (400 – 700nm) wavelengths significantly while blocking or reflecting UV light. Adding an Anti-Reflection coating allows greater clarity in the visible light spectrum by helping to alleviate any inherent reflection in the glass.
Many UV Blocking Glass solutions are said to provide a certain percentage of protection from UV light, often ranging between 96% and 99.9%. It is important to note that there are different kinds of UV light and the amount of protection provided for each kind of UV light is as important as its overall protection against UV. UV B and UV C radiation for instance are significantly blocked by regular glass, but UV A radiation isn't significantly blocked. If an overall rating were given to regular glass it might deceive someone into thinking that their artworks were perfectly fine behind regular glass, when in fact UV A radiation can be virtually unhindered as it passes right through regular glass. Taking this into account means knowing that the UV Blocking Glass you've opted to use doesn't just protect versus UV in general, but is specifically blocking significant portions of the entire range of ultraviolet radiation.