Hey folks,
This is an interesting thread, with some great advice. I want to clear up a couple things that are floating around though. For the record, I am a professional picture framer with 20 years of experience.
0.1 the use of glass or plexiglass should be decided not on price etc...but on what you need the glazing to do. Example: pastel drawings HAVE to have glass. Another example: something very sensitive to UV light will require high quality UV blocking glass (such as antique Japanese prints).
0.2 plexiglass prices vary a lot for many reasons but most importantly remember it is a petroleum product ...
1. In terms of UV protection, neither regular glass or regular plexiglass will do all that much. IF your art is going to be exposed to a lot UV light (this means across from a window or a glass walled room) then you should either: use a UV blocking glazing or rotate your work to reduce exposure.
2. UV blocking plex products like Cryo's OP-3 (which I use a lot of) blocks better than most plain products, about 70%. It is a good product that will help, but it is also very costly when compared to regular glass or regular plexiglass. Expect it to be about 2.5 the money of regular (framing quality) plexiglass. Also, OP-3 and its relatives all add a small amount of yellow color to the image. Regular glass will add green, regular plexiglass is neutral.
3. Not all plexiglass is the same. The stuff in the hardware store with blue plastic covering is basically the worst ... paper wrapped (some is now plastic wrapped but same quality - wrapping is "paper colored") is the best in general. VERY important if you make large works, try to get "cast" plexiglass, not extruded. Expect it to be more $ but the payoff is less "wavyness" and fewer bits of debris inbedded in the plexi.
4. All plexi will scratch pretty easily, be gentle ! Of course you should be gentle with all art in a frame !! The cleaner/polish mentioned elsewhere is great (brilliantize). There are polishes made to take out scratches as well (look for Novus #2 or #3).
5. NOW if you have a real UV problem, ie, either a LOT of light or art that is very sensitive to UV. You are going to have to use a museum quality UV blocking glass. The rub ? It is very expensive, you'll probably be shocked and assume they have made a mistake when you hear the price. Things like Denglass UV is capable of blocking about 97% of the UV. There is not a comparble type of plexiglass so you are stuck with having to be careful in handling/shipping etc. The advantage, as mentioned elsewhere, is that the glass is more clear than even regular plexi. When viewed strait on it simply isn't there. The effect is startling if seen side by side with other products. Many of these are also "non-glare" but that aspect is not from sand blasting (as in cheap non-glare glass) but rather from the use of optical coatings very much like what is on the front of your camera lenses. In fact, when viewed sideways they will have the same purple/green reflections you see on a lens. If you do shop around, PLEASE make sure when comparing prices that you are comparing the same brand, same model. These specialized glazings vary a lot in price... don't just say "UV blocking glass".
A couple of quickies: never ever buy cheap non-glare glass, plexi shouldn't be more than 2 or 2.5 times the price of glass. Shop around a bit and support your local shop.
Sorry for the long post ....
David
