Uv glass identification

Tommy P

MGF, Master Grumble Framer
Nov 16, 2003
Mid North Indiana
I know several ways to check if a glazing has UV coating but I am having sveral customers bring in pieces done by other framers years ago and they want to know if their pieces have plain or UV glass on them. I replace with CC if they do not.

Other than tearing them apart and doing the scratch test on the UV side is there any other way to know if it is UV without taking the package apart? Is there a "black light" test or some other way that will save me the work of a dismantle?
Yes, but again, I would have to dismantle to see the edges.

I'm trying to eliminate the WORK here!
Yes, a black light will show nearly white through UV glass, but violet through ordinary glass. If something white is in the frame, that works. A mat's beveled edge might not be enough surface to discern the color of light, though.

Another way to tell if Conservation Clear was used is to catch a sharp reflection in the glass, such as the edge of a fluorescent ceiling light, which will show a slightly rippled reflection.
Thanks Jim. Does it require a specific type of black light? Would that type of bulb bought at, say, WalMart be okay or does it take a more "scientific" type?
But, John, the original question was about the presence of UV coating. Both Guardian and Denglas have a "UV Clear" version that is roughly equivalent to the TruVue ConClear. Essentially regular glass with a UV coating. The spray application of the Guardian and the dipping then bake application of the Denglas causes a different artifact than the rippling that the roller application of the TruVue has.
Put it in a bright window. If the art fades in a week, it's regular glass. If it takes 10 days, it's UV.

(I'm actually a big fan of conservation clear, but sometimes we expect too much from it.)

Wouldn't it be nice if the previous framer had used a sticker identifying the glass and other components?
Given this some thought today.

Tape a small pocket memo to a dustbuster, having first recorded someone saying "NON UV - NON UV - NON UV" in a robotic voice.

Put dustbuster over glass, wait 5 seconds, turn on pocket memo and say "'Fraid it's normal glass"
Shining a black light through glass in a frame is NOT a definitve test for UV filtering glazing. Only paper and mat board with optical brighteners will glow brightly under black light.
John, you are right; UV light color is not always a definitive test, but it often works. Paper and matboard are often inside a frame, and we don't need a bright glow-in-the-dark indication.

Even in full room light, any surface that would show the violet color of the black light would do the trick. In class demonstrations, we use a small black light and a piece of ordinary white paper -- with the lights on. When we view the light's illumination directly on the paper, it is very violet. When we show it through ordinary glass, it is a lighter shade of violet, because ordinary glass filters some UV light. And when we show it through UV filtering glass, the light's color appears almost white.