From:
http://amasci.com/weird/unusual/e-wall.html
David Swenson of 3M Corporation describes an anomaly where workers
encountered a strange "invisible wall" in the area under a fast-
moving sheet of electrically charged polypropelene film in a factory.
This "invisible wall" was strong enough to prevent humans from
passing through. A person near this "wall" was unable to turn, and so
had to walk backwards to retreat from it.
This occurred in late summer in South Carolina, in extremely high
humidity. Polypropelene (PP) film on 50K ft. rolls 20ft wide was
being slit and transferred to multiple smaller spools. The film was
taken off the main roll at high speed, flowed upwards 20ft to
overhead rollers, passed horizontally 20ft and then downwards to the
slitting device, where it was spooled onto shorter rolls. The whole
operation formed a cubical shaped tent, with two walls and a ceiling
approximately 20ft square. The spools ran at 1000ft/min, or about
10MPH. The PP film had been manufactured with dissimilar surface
structure on opposing faces. Contact electrification can occur even
in similar materials if the surface textures or micro-structures are
significantly different. The generation of a large imbalance of
electrical surface-charge during unspooling was thereforE not
unexpected, and is a common problem in this industry. "Static cling"
in the megavolt range!
On entering the factory floor and far from the equipment, Mr.
Swenson's 200KV/ft handheld electrometer was found to slam to full
scale. When he attempted to walk through the corridor formed by the
moving film, he was stopped about half way through by an "invisible
wall." He could lean all his weight forward but was unable to pass.
He observed a fly get pulled into the charged, moving plastic, and
speculates that the e-fields might have been strong enough to suck in
birds!
The production manager did not believe Mr. Swenson's report of the
strange phenomena. When they both returned to the factory floor, they
found that the "wall" was no longer there. But the production workers
had noticed the effect as occurring early in the morning when
humidity was lower, so they agreed to try again another day. The
second attempt was successful, and early in the morning the field
underneath the "tent" was strong enough to raise even the short,
curly hair of the production manager. The "invisible wall" effect had
returned. He commented that he "didn't know whether to fix it or sell
tickets."
- Bill Beaty
