Perchloroethylene, or perc, has been used in wetgate telecines, film scanners and printers for years. But recent environmental, health and safety regulations in many parts of the world have made wetgate film scanners cumbersome to own and operate.
The idea behind wetgate scanners is that a small amount of liquid perc applied to the film an instant before it’s scanned fills in any scratches on its surface and washes away any dust. And so long as the underlying emulsion isn’t damaged, it can easily eliminate many of the typical blemishes that commonly show up in film. It allows facilities to produce clean files at the front end of the process by eliminating scratches, digs and other imperfections at scan time rather than in digital cleanup.
Perc has been the chemical of choice because of its unique combination of properties – it’s noncombustible, it’s not an ozone-depleting substance, it has a refractive index very similar to film base and it dries quickly.
But the downside is the regulation that comes with it. An advisory from Kodak’s Environment Services group explains that when using perc “workers must be protected against the vapors caused by fugitive losses from the process. Likewise, existing regional and local air pollution regulations may impose further restrictions on usage and emission controls. At the end of its useful life, waste perc is subject to a strict waste management regime that may include many regulatory restrictions associated with recycling activities.”
But a German company – Kodika Elektronick – has developed a replacement chemical for wetgate scanners, with none of the environmental, health or safety concerns. The company is keeping the chemical’s name and composition under wraps for now, pending patent approval. At IBC, Arri previewed a prototype of a 16mm wetgate for its Arriscan based on this new environmentally friendly substance.
“Perc really requires a gas mask if you want to work with it,” said Elfi Bernt, Arriscan product manager. “This liquid is nontoxic, and that’s why we can show it at IBC. We are allowed to use this liquid on the show floor.” In addition, says Arri, the liquid “perfectly matches the refraction index of the film carrier.”
Imagica is also eager to explore this new chemical. The company won a Scientific and Technical Academy Award in 2002 for its Multi-Format Optical Wetgate Printer, and currently offers a wetgate system for its Imager XE Advanced Plus scanner.
“Imagica has already been providing perc-based wetgate solutions for our scanners, and we are very interested in supporting this more environmentally friendly solution,” said Richard Antley, VP, Imagica Corp. of America. “I could see this leading to a surge in wetgate use for scanning, and possibly a resurgence in wetgate printing,” he said.
In 2006, Los Angeles-based IVC Digital Film Center was the first post house in North America to install Imagica’s wetgate system on its Imager XE Advanced Plus scanner for 2K and 4K DI and restoration projects.
At the time, Jim James, IVC’s chief engineer, explained the advantages of wetgate scanning: “By doing a wetgate scan, you can drastically reduce the amount of digital cleanup, saving time and money. Whereas digital cleanup requires you to go in later to replace bad pixels with new pixels, the necessity of these time- and labor-intensive fixes is reduced or eliminated following a 2K or 4K wetgate scan because the imperfections are never captured.”
“It’s not as friendly as it should be, and it’s getting more and more expensive, and eventually it’s going to have to go away,” said Dick Millais, VP, marketing, IVC Digital Film Center. “But we really depend on perc doing what we do. If there’s a viable alternative that doesn’t cost more money and will run in our liquid gate printers and liquid gate scanners, then why not?”
“Liquid gate printing is sort of a black art,” he said. “You have to have people really familiar with liquid gate the vagaries of handling of it, and you have to be very, very vigilant,” he added.
“The only issue with using a wetgate device is that it cannot help if the emulsion itself is damaged. It is otherwise quite effective,” said Antley.
Written by Scott Lehane
