In article <5rjuv2$h1u$1@news.ccit.arizona.edu>, deyoung@u.arizona.edu says...

>I just finished going through some of my filters that haven't been used in
>some time, and I discovered a slight fog on many of them. It cleaned off
>fairly easily, so no big deal, but I'm wondering where it came from in the
>first place.
>
>My guess, though I can't verify it since I had cleaned them all before it
>occurred to me, is that it might be related to these little packets of
>silica gel desiccant that comes with them usually -- I stored most of them
>in the original plastic Tiffen case with the desiccant. A few didn't have
>one, and a few weren't fogged, but I can't say for sure it was the same
>few since it didn't occur to me until later.
>
>Has anyone seen this kind of problem before?

Spontaneous fogging seems to be a Tiffen filter trait...;-)
I buy Tiffen only when absolutely necessary (to get colors
not available elsewhere at a reasonable price), and, when
I can, remount the glass in better rims. Unfortunately,
they still fog (even when stored without the gel packets,
and in Nikon filter cases, which do not fog Nikkor filters).
Try Hoya, if possible - they are a reasonably-priced, better
alternative...
Hope This Helps
(David Ruether - http://www.fcinet.com/ruether )