Paint is Fading Looking for Test 4

[Cervantis]

I have been asked to investigate a problem that involves fading of paint when exposed to sunlight for longer than 3 weeks. The surface material is Aluminum. The paint color is black. The product comes in already painted, and we affix it to another part. But after 3 weeks the painted surfaces changes from Black to Grey. We suppect that the UV additive was not used, but we can't figure out how to tell with a simple quick test. We have a UV chamber, but this test is 500 hours or 20 days. Any IDEAS on how to test a painted surface for UV protection quickly.

I thought I would use the most powerful tool in the universe, ENG-TIPS.com to find a conclusion to this conundrum.

Best,

Cervantis

 

[tnatale]

A couple of points:

As the base color is black, the most likely pigment is going to be carbon black. In general, carbon black is very UV stable and is used as a UV stabilizer.

What you are describing seems more like chalking, which is typically a breakdown of the resin, which turns light colored and powdery.

There are ASTM tests to measure chalking.