The primary purpose of glazing in art framing is to physically protect the work of art from damaging factors such as humidity, heat, and soiling. Laminated glass and some acrylic may be used to protect against physical damage from glass breakage and to offer protection from a malicious attack. Regular glass as well as some glass surface treatments can also filter some of the damaging ultra-violet radiation (UV) and heat (NIR). Artworks that require protective glazing are those rendered on paper or fabrics (including photographs), which contain pigments and dyes that absorb UV and are susceptible to discoloration. In the case if the framed object or artwork is UV resistant, UV protection can still serve the purpose of preserving the integrity and colors of non-conservation grade framing materials susceptible to UV damage, such as mat board (passe partout).
The chart below details all the types of glazing we can use for your design. There are a lot of options, but most projects can be narrowed down to much fewer choices.
For more information, and a larger version of this chart
click on the image for a link to the manufacturer.