OK, I am in the middle of an experiment on this very phenomenon. Like Lynn, it involves Fusion seals. I had the same wrist problem more than a year ago, and those seals were replaced and are just fine now, more than a year and many dives later.
I take care of my seals very carefully; I cannot imagine that anyone could be more careful than I. That is why I was very frustrated a couple of months ago when I saw a gooey spot in the middle of my neck seal, on the outside. I got through a day of diving, but I knew I was in trouble. (I was nowhere near a pool when it happened, and my wrist seals were always exposed to the same waters at all time. The waters in which I was diving were in an inland, fresh water sink hole that has no contact with any potential source of pollution.)
I was very busy after that, so I did not take the suit out to replace the seal for nearly a month. At that time, I saw that the gooey spot has spread considerably and gone clean through the seal. It was like my seal was being attacked by a flesh-eating bacterium. It continued to spread after that.
Once I got the seal off, I cut the unaffected parts into squares and introduced potentially harmful chemicals. I put suntan lotion, all my toiletries, mask defogger, gasoline, alcohol--anything I could think of that may have contaminated the seal on those squares.
Nothing happened in any case.
I talked to a chemist who said he would be surprised that seals would have this problem, since he would think they would be engineered to resist anything of this sort. He mentioned the fact that it seemed to be spreading, and suggested the possibility that, given the fact that latex is a natural product, the problem might be organic. I therefore cut out two similar patches of affected seal and put them in baggies. I heated one in the hope of killing anything biological. I also dabbed some goo on an unaffected square. I want to see if one continues to spread and the other does not. Of course, if nothing happens nothing will be proven, since the spreading may have stopped already on its own.
Another chemist was contacted, and he had another thought:
The question first asked should be "Why is the material failing under its intended use application" not What is causing it to fail?
Elastomeric and polymeric materials are highly crosslinked compounds making them a 3D network molecule which can't be dissolved in solvents. Sun lotions could act as a solvent but should only be absorbed without significant change in the material other than swelling. The "goo" is an indication that the rubber, latex or other material is slightly dissolving which make me think the material is failing because it is: 1) the wrong material for this application or 2) it is defective due to improper or incomplete polymerization or crosslinking.
Also, how much sun expose does the collar receive while not being worn? If one assumes sun lotions are absorbed in the collar, they might aid in photodegradation of the material under the sun. But this still brings us back to why is the material failing under it intended use. So I might conclude that the collar is defective.
So, I don't know, but I do know it is happening in more than a few cases. I would hope that the manufacturers who are having this problem would do a study of their own to find out why it is happening. I read an online posting by a manufacturer that suggested that the problem was
probably caused by pollution, especially gasoline from outboard motor engines. One application of gasoline to a piece of my seal proved that this is not true. I would think they would have tried that themselves before offering it as an explanation.