Recently a client asked if we would examine a frame made some years ago and determine if the glazing blocks ultra-violet light. Some of the media used in making the work were almost certainly light sensitive, so the collector wanted to replace the glazing if it did not block UV. To test the acrylic glazing we used an ELSEC UV meter, which measures UV values as the proportion of ultra-violet light to visible light.
We fist tested the glazing under the fluorescent lights in our showroom. In the first three images below the meter registers 25 microwatts per lumen with no glazing, and zero mw/lum under the glazing, indicating that all or virtually all the UV is being blocked by the acrylic.
we also used a UV "black light" lamp for a second test. As shown in the fourth image, the meter indicates 5000 mw/lum from the back light source without glazing, and under the glazing 30 mw/lum; showing that the acrylic is blocking over 99% of the UV.
We told our client that his glazing did not need replacing.