Glass can be a basic affair or it can go high tech (with a higher price to match). The main things to consider when choosing glass for a specific project are reflection, UV protection and safety.
Regular glass – standard glass is readily available and the least expensive option for framing. It will help protect your artwork from dirt, splatters, humidity and bugs, but will only block about 40% of UV rays, and its shiny surface has quite a lot of glare which can interfere with viewing the artwork behind it.
Plexiglass – The main reason to choose plexi is for safety. Is the piece intended for a child’s room? Does it need to be moved often? Plexi is lighter and won’t break. It is also available in larger sheets than standard glass, so it is often the best choice for really large items. The downside is that it scratches more easily and can be staticky, which can create a problem with pastels or other loose materials.
Non-glare – this glass is etched on the surface, diffusing the light which passes through it, and cutting down on glare. It works best if you are framing with a single mat, as the hazy surface becomes more pronounced the farther away it is from the item behind it – definitely not a good choice for a shadow box or something you are framing with a triple-thick mat. It does not add any more UV protection than regular glass.
UV glass – UV glass blocks out up to 99% of harmful ultraviolet rays, protecting your artwork from colour loss and paper embrittlement. Valuable, sentimental, and one-of-a-kind pieces warrant the extra protection given by UV glass. Keep in mind, though, that UV glass does not reduce glare.
Anti-reflective glass – Anti-reflective glass has an optical coating which cuts down drastically on light reflection and renders the glass nearly invisible. Most anti-reflective glass will block some ultraviolet light, but not all, and is not considered conservation grade.
Museum glass – This glass truly has it all. It combines an anti-reflective, nearly invisible finish as well as a UV coating that can block up to 99% of UV rays. For valuable works of art it is the way to go.