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Static: The "layers" of film stick together and an extra "loop" of film tries to go into the brain, sometimes casing a wrap. Answer: Get FilmGuard.

Damage: Usually becasue somebody mis-threaded the projector somehow. As the film rewinds on the platter it will seem to grow in diameter. It will also be kind of "spongy". That's becasue the sprockets in the projector have jumped the track, so to speak and have put little "dents" in the film. These dents push the layers apart becasue they act like "spacers" betwen them. Answer: Inspect the film. If it's damaged you'll have to get a new print.

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Excessively dry conditions in the booth can also cause winding problems. When the relative humidity is very low (e.g., in the winter when the heat is on, or in a desert climate), the gelatin emulsion on the film loses moisture to the dry air and shrinks temporarily. Since the polyester film base doesn't change much with humidity, the shrinking emulsion pulls in, causing the film to cup or curl excessively. Severe curl or incorrect winding tension may cause the film roll to wind unevenly, or take on the shape of a polygon ("spoking") instead of a perfect circle.

Kodak recommends maintaining a relative humidity of 50 to 60 percent in the projection room. At very high humidities (greater than 65%), the gelatin emulsion may actually get more soft and sticky, and the film can have "negative curl". At very low humidities, the emulsion shrinks so the film will have excessive "positive curl", and the film surface becomes less conductive, so static dissipates more slowly.

Every projection room should have an accurate humidity gauge to measure relative humidity. The low cost digital gauges sold by Radio Shack (e.g. Model 63-855) and Edmund Scientific are surprisingly accurate. Another quick gauge is to simply observe a short clip of free-hanging print film. It should have a very slight amount of "positive" curl, where the edges of the 35mm film curl upward only a few millimeters.

If the humidity is too low, use a humidifier to add moisture to the air. In moist or tropical environments, a dehumidifier or air conditioner may be needed to keep the humidity under 65%. Adjusting the HVAC system balance may help too.

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Speco platter #3 was a loose winding kind of platter and the projector in #3 was embossing the film because one of the pad rollers was too tight to the sprocket. When I moved the print to the platter in #5, also a Speco, but one that wound tight, the damaged film would "cone up."

I adjusted the pad roller and that was the end of that problem. How do you adjust the pad roller, you ask? You take two pieces of film and thread them over the sprocket like you would with one. Then you try to turn the pad roller. if it is too tight, you adjust the pad roller stop-screw. The pad roller should just be loose on two thicknesses of film, but tight on three thicknesses of film.

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