Static Electricity Problems with 35mm Sound

[Paul Finn]

Since the subject of a static electricity charge on film has come up again, I'm wondering if there are known issues, or historical information available, about 35mm analog (SVA) sound being affected? If so, what was identified as the affect and what corrective measure(s) were taken?

Thank you, Paul Finn

[Marcel Birgelen]

Since analog SVA sound is scanned optically, I'd expect this not to be a problem, unless the buildup is so enormous, it causes actual arcing in the reader.

[Ryan Gallagher]

Since analog SVA sound is scanned optically, I'd expect this not to be a problem, unless the buildup is so enormous, it causes actual arcing in the reader.

and if there was that kind of build up, you'd think it would be shed to ground somewhere before the optical reader. Attic mounted SRD might be a different story, first in the path, but still would require arcing, which you'd probably see/hear while operating it?

Other than platter woes, an mag sound, static's main concerns are in it's hunger for dust and dirt and shed to cling to the print.

[Jim Cassedy]

The old (actually, ancient) optical sound heads used phototubes, and some soundheads
even had a small pre-amp which used one or two vacuum tubes to boost the phototube
output before sending it to the main amplifier. I know those pre-amps were vary high-gain,
and I suppose small static discharges might have been picked up by their primitive electronics,
although I don't recall it being a big problem. Microphonics, from loose elements in either the
phototube amplifier tube(s) were a much bigger problem.
I do recall visiting several projection rooms not long after platters became commonplace and I
would quite often see metal Christmas tree tinsel or garlands hung in such a way as to contact
the film as it left the platter. I was told back then that this was to drain the static electricity charge
off of the film. I think the acetate film running over the plastic platter rollers would pick up a charge,

[Marcel Birgelen]

I do recall visiting several projection rooms not long after platters became commonplace and I
would quite often see metal Christmas tree tinsel or garlands hung in such a way as to contact
the film as it left the platter. I was told back then that this was to drain the static electricity charge
off of the film. I think the acetate film running over the plastic platter rollers would pick up a charge,

That stuff is made from vinyl coated with the thinnest possible layer of metal. So thin, you can even see through it in most of the cases. You'd expect that stuff to have a conductivity of close to nothing, so I guess they only made it worse with their Christmas decorations serving as improvised lightning rod.

[Jack Ondracek]

Considering the projectors are well-grounded through conduits, utility wiring, cable shields, etc, the film has to travel a long way through serious discharge construction before getting anywhere near an optical reader, which has its own isolation... as noted by others above.

The tinsel over the film is an interesting idea, but I can't see it addressing a problem that wouldn't be drained off along the natural film path, if it existed at all.

[Gordon McLeod]

Static discharge to a stereo solar cell was a issue during dry canadian winters with the Bauer U2 the film would build up a static charge on the plastic gate bands and discharge to the solar cell causing static noise and in one case blew the cell apart. At that location we ended up putting a thing piece of copper foil on the top of the cell just folded slightly down and connected to the chassis

[Mark Gulbrandsen]

I thought Eastman applied a coating on the release print material that killed the static issues. Having worked in States that had extremely low humidity, I remember this being somewhat of a problem on release pint material in the very early days of Estar. It created havoc on some platters where several layers of film would stick together and on occasion get pulled into the pay out head... We called it Stiction... I also remember that Film-Guard pretty much cured the issue, and a year or two later Kodak applied a clear coating of some sort that killed the static. I do not remember any sound problems...

[Ryan Gallagher]

Such things are probably used in film lab settings... but has anyone ever deployed an ionized air knife or other blower to dissipate static charge in a booth? Maybe after platter pay out or before platter takeup? Overkill for sure, but fun idea. There are all kinds of shapes and sizes for assembly lines or clean room application.

I remember you could get some similar things for dark rooms sized for 35mm too. I might even have one in storage.

Normally i'd say blowing room or compressed air across the film is a bad idea for contamination, but the with the dust static collects, it might be the lesser of the two evils.

Here is one company:

https://www.exair.com/products/static-eliminators.html

Here is a workbenchy sized "fan" form factor unit for sensitive electronics:
https://www.keyence.com/landing/stat...r_01171439.jsp

[Mark Gulbrandsen]

Such things are probably used in film lab settings... but has anyone ever deployed an ionized air knife or other blower to dissipate static charge in a booth? Maybe after platter pay out or before platter takeup? Overkill for sure, but fun idea. There are all kinds of shapes and sizes for assembly lines or clean room application.

I remember you could get some similar things for dark rooms sized for 35mm too. I might even have one in storage.

Normally i'd say blowing room or compressed air across the film is a bad idea for contamination, but the with the dust static collects, it might be the lesser of the two evils.

Here is one company:

https://www.exair.com/products/static-eliminators.html

Here is a workbenchy sized "fan" form factor unit for sensitive electronics:
https://www.keyence.com/landing/stat...r_01171439.jsp

Not really, but they are very common in film labs to help remove a given chemical completely. For theaters, Film Guard was a better choice, because it killed the Static, kept the print looking like new, and eliminated a lot of wax and emulsion buildup in the projector. Plus, theaters kept using the cleaners after the static issue was fixed.The new release print film was released in 1999.

[Josh Jones]

Many of the older machines had the optical playback assembly mounted an an isolated chassis to reduce vibration noise from the gear train. As such, it was sometimes not that well, if at all grounded, and static noise was a problem. I believe most of this went away with reverse scan readers.