In article <4btt1q$6ka@sirius.intxpress.co.nz>,
edison@nelson.planet.org.nz says...
>I believe that any flexible plastics such as foam and vinyl constantly
>emit small quantities of gas from the solvent that makes them
>flexible, storage in proximity to other plastic and rubber and one
>will affect the other. I've has the vinyl/cardboard case of my
>Nikkormat EL collapse when stored in a drawer which had some
>polysterene foam in it and the foam light seals are shot too. Others
>may disagree but I think the best place to keep a camera is just on a
>shelf in a room in the house which is not suject to extreme
>conditions and with a dust cover over it so as to allow the air to
>remain 'fresh' around it.

Seems reasonable to me, and the best explanation I have heard that
would account for the seeming randomness of the occurance of gooey
foam - and (fortunately) I have stored cameras and lenses for years
on open shelves (with paper towel dust covers) - has worked well so
far for me. Thanks!
Hope this helps.