I have seen figures who have been graded with a clear bubble. But the bubble has started to turn yellow after it was graded. My chief chirpa the only yellow i can see is from the tape holding the weapon.
I have figures that are graded "Y" that have better (less yellow) bubbles than others that didn't grade "Y" it just depends on the condition of the bubble when graded, how it has been kept since it was graded and probably the mood of the grader as well.
The joys of AFA.
At the end of the day all the bubbles are going to yellow and drop off eventually.
Yep agree with Ron, they won't just fall off, seperation can occur on MOC's with weak seals, normally a corner or the bottom but these are going to be around for a long long time, yellowing however is something that even with precautions can happen!
Depends how they are stored i keep most off my stuff out off sunlight. I had a lot in the loft before but that was a bad move because of the temperature
The only yellow i can see is near the tape. I have a few Kenner's that have yellow bubbles which have got worse even though they have been stored away. That's the joy of MOC collecting.
I agree most bubbles will turn yellow eventually but we cant predict when. Some lines are definately more prone than others.
Regarding bubbles falling off with age.
If you have beater card with a sealed bubble try and push down on the top of the bubble to simulate gravity and you'll get an idea of just how strong the seal is. As Ron said its been 30 years now and they haven't fallen off personally i dont think they ever will at least not in the next 100 years 8)