"Jeff Wisnia" wrote in message
...

stuff snipped

What happened is that the eye screw securing one end of the picture wire
had pulled right out of the frame wood. No one was there fiddling around
with that painting when it fell.

I would say it was a combination of the wood aging and the screw-eye
responding to years of vibration. Screws depend on friction to hold, and
each passerby vibrates the screw and can eventually cause it to loosen
because the weight of the picture is constantly trying to "unscrew" the
screw. That's why Locktite exists. (-: Screws have been loosening
themselves forever, from both wood and metal and metal's not likely to
respond to high humidity. It also sounds like the original choice of
materials was not suited for the job at hand.

If you ever had street paving done, you know how much pictures rattle around
on the wall when the use a compactor. The weight of the frame plus 25 years
of vibration could have easily loosened the screw-eye enough to have pulled
out, especially if it was undersized to begin with. Would heat or humidity
effect it? Sure, different materials expand at different rates from the
heat. In this case, though, I think it was just time and the natural
tendency of a screw under load to unscrew itself.

--
Bobby G.