I found this thread on the PSA message board about an experiment that was done on the affect of light source (natural/artificial) exposure to PSA slabs over a 90 day period. The results are extremely interesting.

Light Exposure Experiment on PSA Slabs

I keep my SGC / BVG cards and some autographed baseballs on a mounted shelf around the top of my office walls. In essence they are exposed to artificial light 1/2 day (2 60 watt bulbs with a frosted glass shade on ceiling light) and the wood blinds are kept closed ~90 percent of the time, as I'm cognitive of the affect of any direct sunlight. I haven't noticed any problems, but this has me genuinely concerned. I enjoy keep the cards 'on display' 24/7, and the thought of keeping them in boxes is disappointing. I've had this shelving system up for about 1 year. I haven't noticed any fading problems.

I inquired to SGC about their UV protection when I built my shelving and received a response that they should be fine in artifical light, but it wouldn't be good to keep them in direct sunlight. I don't recall any definitive statement from SGC on the UV technology of the plastic or any concrete information. I'm going to contact them again.

All the major card grading companies should be using UV protection in their plastic casings. It doesn't appear that PSA is given the results. Does SGC? Does BVG? I'd surmise that they don't. If they did, you think it would be noted.

Your comments, especially with the affect and any technology information on the SGC slabs are welcome.

Enjoy Your Collection & SKOL VIKINGS!