I'm just now getting around to publishing this test. Before I started putting in nice wood and Fender guitars, I started with some cheap guitars, including an SX Strat, and this garage sale beauty, a First Act mini flying V. The test was pretty broad based, just throw a bunch of light on the face only, and see what happens. I'm not exactly sure what the finish is, although my guess is that it is a urethane based finish, as that is what is most common in the continent of Asia, where this is from.
For this test, I used two rigs, including my low power guitar rig (6x SG-1-40T12 lamps @ 32W) and the rig shown in the image, which has the 20" version of the same lamp (SG-1-20) being powered with the WH8 ballast @ 27W each. Ironic that this smaller rig is actually higher powered, but I build the lamps to run at different levels, so I test them at different power levels. the first week was in the big rig, however.
Let me be clear, I don't consider this a conclusive test, as a lot of unexpected things happened. For starters, after a full week in the big rig with the lights on 24/7, I didn't see a single change in the finish. Zero. That was odd since I expected at least some oxidation. So I left it in there another week. Now I started to see some small differences, in particular, gold flakes in the finish. Literally, it looks like gold glitter. Not a lot mind you, but it is there if you look. I also noticed some stress lines in the finish. Now, I try to vent the rig well and do a good job, so I don't think this is heat. In the picture below, I show you as best as I can, and I make sure the bridge is in the photo for scale. Even though this is a mini, the bridge is the same size as a full sized guitar. You can also see some of the wavy in the finish here.
Next we did a week with the smaller but significantly higher powered rig, vertical instead of horizontal. (this shouldn't make a difference) and the amount of stressing lines in the finish jumped up a good deal. it is hard for the camera to catch it, and my photography studio isn't setup for guitars, but for very small or very large items, so the best way is showing you the reflection of the overhead fluorescent lights. it is pretty obvious here. Some of those dots are dust, some are gold specs. I did include a bit of the neck for scale.
Just above the reflection, you can see a few hairline cracks in the finish, and this photo is pretty color true as well. The bottom image accidentally caught my workbench and the centimeter guide, which works really well for giving you scale. Lucky accident.
None. I've shot UV through thin urethane finishes to age necks but have I've not had them buckle the finish like this; urethane is pretty tough. Necks finished with THIN coats of urethane are easy to age and the finish doesn't block a lot of the UV. I need to buy a used Mexican or Chinese Telecaster to test with, as those have a very thick coat of finish, and the only spare necks I have with that finish have artificial tinting to them, which I hate.
At the end of the day, what happened to this guitar is not what I would have wanted on purpose, although that is in the eye of the beholder. It was a bit too erratic. I've exposed Chinese urethane finishes to UV before (A quilt top, sunburst SX Hawk, Strat copy) and while it faded unevenly, it didn't crack. My guess is the guitar finish is the issue rather than my method, but I haven't ruled anything out. Regardless, if I test it, I will publish it, and maybe it will offer you some info.