Hello.
I noticed that some of my florescent lamps seem to glow a greenish color under a blacklight bulb.
The odd thing is, none of my other lamps do it. The only lamps that do it are all of my GE reveal linear florescent tubes and a relabeled Philips F40T12 Cool white florescent tube. [datecode being 6E so i think the lamp was made around may of 1996]

I wonder if anyone else has seen this as it's quite interesting.

Hmm that is unusual indeed. Perhaps part of the phosphor is very sensitive to UV light more so than other components giving the green glow?

What color designation are they ?

my philips alto does this, I've noticed it when i swap it from my fluro fixture for the blacklight tube, it always likes to glow green, its usually sitting right next to the fixture after i swap it out, my old sylvania merc likes to glow a pink colour aswell, but my philips merc does not, some of my CFL's do it aswell, they glow a skyblue colour

My philips alto 13w florescent PL lamp seems to glow a faint blue color under blacklight.