"Rich Grise" wrote in message
news
After about 10 years, it got a black spot that grew so fast that
the thing was useless in a few months.

This happens when moisture gets under the lamination. I'm not sure of the
exact failure mechanism (what _precisely_ does the water do the to EL
material -- react with it? or just support growth of, e.g., mold that
subsequently destroys the material?) I had a similar experience to yours,
although in my case it only took ~5 years. I went to the company's web site
(http://www.limelite.com/) and found that the early models were known to
have such a problem but that supposedly it's been fixed.

---Joel