Sal Santamaura
Member
Both Tru Vue AR glass and Art glass only filter about 70% UV light. Conservation clear and museum glass both filter 99% UV light. Wouldn’t you want more UV light blocking for your prints?...
Black and white prints framed behind glass that filters less of ambient UV are not an issue for me because there's almost no ambient UV in the house. Windows are double-pane, so they're already removing 0.7 x 0.7 meaning 51% of any daylight UV is getting in. Framing glass multiplies 0.49 x 0.7 meaning only roughly one third of any daylight UV could possibly reach the print. I don't ever let direct sunlight hit a frame, and even indirect sunlight, i.e. reflected and/or diffused by shutters or blinds is rare throughout the day/year. I have no fluorescents or halogens anywhere; LEDs now provide all the artificial illumination here. Thus, UV is a negligible factor in the deterioration of those prints. Visible light "wearing out" optical brightening agents represents a print life expectancy determinant orders of magnitude more significant than UV. The short answer to your question is "because plastic UV blocking layers on glass distort the color of mats and prints, that's why."
In California, frame shops discourage using glass in framing pictures and photographs. They recommend plastic.
I ignore that recommendation and always have. Any framed pictures hung in my California home are secured to wall studs. They do not move in earthquakes we've experienced up to around magnitude 5.6. Anything larger than that and I'll be more concerned about the house and our safety than the prints. In the meantime, I enjoy looking at images unimpaired by static-charged, scratch-susceptible acrylic and the dust it's attracted.
But in the end, isn’t the ideal for the final print to be framed and displayed, and not sitting in a box or flat file somewhere?
There are many things in life that are less than ideal. Given the choice between ending my making of prints when wall space to hang them runs out or continuing to enjoy photography by making prints and viewing them from time to time, I elected the latter. Your priorities may differ.