Blacklight test weirdness, guitars glow, that shouldn't

Hi folks, this issue might have been discussed before, but I haven't been able to find a satisfactory answer.

So here we go: I did said blacklight test on one of my old guitars, a 1975 Guild Starfire, which I expected to glow in the dark, and it did. No surprise here, since it's nitro lacquer.
But I also tested a couple of other guitars in my possession, namely an Ibanez Artcore AFS95T, which I bought just a couple of years ago, and which should not be finished with nitro. Sure enough it did have this greenish glow. The headstock of the guitar is black, but under blacklight it glows green. It's harder to see on the body, because it's greenish under normal light anyway. But it glows!
How's that possible? It's way to cheap a guitar to be finished with nitro.

I then tested my old Takamine Hirade E90 classical guitar from 1984, which was a top of the line Takamine guitar back in the days, but still the finish shouldn't be nitro. It's way to durable and feels very much like poly or whatever modern finish they used back then.
You guessed right, it also glows under blacklight. Some parts don't glow as much, like a bit that chipped and got fixed years ago, as well as other parts that you'd expect to have some wear. Nowhere though has the finish been worn to the wood (which a nitro finish on a well played guitar would have). So I highly doubt that it's a nitro finish.

This got me thinking. They say, the blacklight makes nitro finish glow in the dark. What if blacklight makes other finishes glow too? It seems that this test is no reliable test whatsoever whether or not a guitar was finished with nitro. All it does, is expose repairs. But other finishes glow as well. Or do they?

So did I get this wrong in the first place, and this test has never been a reliable way to identify nitro, or does this mean, that the guitars in question must have been finished with nitro, as unlikely as it might be?

I'm really looking forward to your replies, as this got me well confused.

And since it's December 31st, I wish all of you a happy new year 2018!

Thanks!

 

Oh, so I see. The blacklight test does NOT say anything about whether or not it's nitro, it only helps to find inconsistencies in the finish.
It's a fair point that all sorts of other materials will also glow. I didn't think of that, but it's of course something I should have been aware of. So it's not surprising that some of my cheaper guitars with poly finish would also glow in the dark.

Thanks for our input, folks!