Float Glass
Clear picture framing float glass is most common and least expensive for general purposes. Often called standard glass, and not be confused with lower-quality window glass.
Diffused Glass
Diffused glass or, or non glare is about twice the price of clear glass. Its etched surface blurs the image when viewed from side angles, especially when glass is properly separated from the art surface, the more the separation the more the blur.
UV Glass
Ultraviolet-filtering glass is available clear or non-glare, and is recommended for all preservation projects. It is coated inside to filter out more than 95% of harmful UV light, which may cause fading.
UV rays are in all light, but very strong in sunlight and fluorescent light. Cost of UV-filtering glass is about twice the price of non-glare glass.