09 · 18 · 17

How do you restore an old film?

By: Gabriela Martínez @GabbMartivel

Seeing a big screen classic projected directly from the nitrate roll is an experience you rarely have the fortune to relish. The high amounts of silver in your emulsion allow you to project luminous and bright images in black and white with a range of greys that a digital copy can hardly reveal.

Getting a direct copy of the original film, whether nitrate or polyester, involves a deep and sometimes long restoration work that can take months or even years.

Accompanied by Francisco Ramírez Vázquez, head of the Cinematographic Laboratory of UNAM’s Film Library, we toured the facilities of this institution to know the process of restoration of an old film.

The objective of the cinematographic laboratory is to maintain the material of the film archive of the library in good condition. Many of these materials arrive in poor shape or duplicates, so a review of their conditions and verification that there is a copy of the same work. Generally, the films arrive by means of donations, and many of them are silent cinema of the 20s. It is important to preserve them because there are few copies.

“Rescuing them implies making a new negative, scanning and doing digital restoration because, over time, the characteristics of the film change: it is unstable, it moves a lot. The films begin to deform or contract, so you have to give it stability and return the correct tones,” said Francisco Ramírez. He added that the best aid for preserving them is polyester film (16mm, 35mm or 9.5mm) because it is a secure medium that can be stored for up to 300 years, unlike a digital copy that if it is not migrated to data constantly, can be lost.

The evaluation of the material

Once a copy is accepted for restoration and conservation, it must go to the workshop. Here we review the technical file of everything that comes and the classification is done to enter it into the database of the file. To find out what year the film is from, we look for symbols engraved on the side of the perforations, which are then compared with a list of codes used to identify the year of production of the film.

In the workshop, the negatives or positives of the films are rehabilitated and restored, since there are materials that come with the so-called vinegar syndrome, which is known as the natural decomposition with the passage of time of the acetate film, which acidity makes it smell like vinegar. The damage caused by this syndrome is measured with a pH strip that helps to determine the degree of acidity, then the film is “vaccinated” with the help of desiccants and sealed in a can so that, within a period of approximately two months, it can be re-checked to see how much of the material has been recovered. In case the film has not been fully recovered, a photochemical (picture) restoration is done frame by frame and manually.

Movies with vinegar syndrome.

pH strips.

Nitrate films, for their part, can be damaged by sulfation of the material, which causes the material to harden, turn to dust and become unusable.

Inside the workshop sections of films that no longer have the perforation to pass through the projector and the machines of the laboratory are also repaired. This is achieved with perforated tapes and a perf-fix machine, used to add those missing pieces of films.

‘La muerte de Carranza’ (1919, Dir. Salvador Toscano)

Perforated tapes.

Perf-fix machine.

Developed in the laboratory

Once the original film is physically restored, it needs to be transferred to a new support (polyester film) to ensure its preservation. In order to be able to project a film, it is necessary to develop it, so in the laboratory there is a development room where the latent image is printed so that it is visualized on the new support and can be projected again. “Here they are made in 16mm and 35mm only for black and white films because almost everything that is restored and needs to be developed is in those colors. When color development is needed, we go to the Churubusco or Labo Digital facilities,” explained Francisco Ramírez.

This process is made by a developing machine and is similar to the photographic development: it is done with red light and chemicals are used that allow the image to be revealed in the new support. It is then rinsed and dried, just like a photograph.

Before doing a development, the laboratory should do a chemical analysis based on the Kodak manuals to know how many and what liquids are needed to develop, as well as the temperature at which the developer liquid should be and the time the film must be in it.

“A second review of materials is done in the lab to see the conditions in which the film is going to be printed. Marks of synchronization between image and sound are checked; for example, they take distances, clean negatives to avoid contamination projected on the screen,” added Francisco Ramirez.

Developing machine.

Chemical analysis control.

The polyester films where the new copies are made have a shelf life of five years and are stored in freezer chambers that allow keeping the materials at 10 degrees Celsius.

Rescue by optical impression

With the optical printing machine, it is possible to rescue shrunken or fragile materials and can be enlarged to obtain, from a film in 16 mm, a 35mm copy. When the film leaves the workshop and still presents conditions that make it difficult to manipulate, it takes to this machine that has a small projector that allows seeing the image during the process of printing in the new support to verify angles and frames, frame by frame, to get a good negative. This is a laborious process since a two-minute stretch can take up to three days to be rescued. “Sometimes the film can get out of position and we have to stop the printing to readjust frames and angles before we can continue,” said Francisco Ramírez.

Optical printing machine which was used to add special effects.

Sometimes the perforations of the film are different from those allowed by the machine, as the first films had smaller, round perforations, and there are any machines that can carry them anymore. When obtaining a copy of materials with these characteristics, the process may take longer, as the film does not get caught correctly in the hooks of the machine, causing the frame to continually slip, enlarge the perforation or damage the tape. “It is the only way to obtain a copy and manage to rescue those films to bring them to a new medium that allows the image to be digitized,” added Francisco Ramírez.

Automatic correction of color and light

The automatic corrector of color and light works by means of an automatic optical system and electronic cards that allow stabilizing the light in the new copy. This machine is used when the materials are in good condition and can do in an hour the work that in older machines could take up to three days. The machine mounts the image and sound separately. It is a process that is done with the light off to avoid the development and allows to print the new negative of image and sound at the same time. Once you have the copy with the light correction, you can develop it in the laboratory.

“Previously, there were techniques to color the films even though these were in black and white. This is called dying and turning. In some cases, the filmmaking factory, Kodak, painted the entire film in a single tone – it could be red, green or yellow – and that’s where the images would be printed on.”

Filming of the movies was done in different light conditions. If you do not level the light on the negative and make the impression with a single light value, the projection may look darker or brighter at different times. When it comes to color movies, the images may look green, magenta, red or yellow.

Previously, the correction was done manually with the help of another machine, and the person who did it had to be based on a piece that allowed to maintain the control on the levels of light in the film. The problem was that sometimes there were very short scenes, and the change had to be made very fast so that it did not have different levels, which did not guarantee that the light levels were the same.

Francisco Ramírez explains how the automatic corrector of color and ligh tmachine works.

Digitization Rescue

Once restored, they go to the scanning area where this form of rescue can be applied. Here a special machine is used with soft reels that do not damage the films, although they are in bad condition. With the software included in the scanner, you can frame, correct light level, scan to full HD or to a more compressed file.

Digitization of ‘La marcha de Zacatecas’ (1968, Dir. Raúl de Anda Jr.) in 16 mm

“Sometimes movies are ‘dismantled’ and must be rebuilt through research. Such was the case of El tren fantasma  (1926, Dir. Gabriel García Moreno), which took two years of research to restore. With this film, for example, a way to digitally substitute missing frames and adding the subtitles from typographies similar to those to the original film had to be found,” Francisco Ramírez explained.

UNAM’s Film Library Medal

Since 1987, UNAM’s Film Library recognizes personalities or institutions that contribute to enriching the film heritage of the world in all its aspects with their history, activities, analysis and interventions in the world of cinematography.

The medal, which is presented each year during the Morelia International Film Festival (FICM), is a symbolic and artistic work that is 99.9% pure silver extracted during the process of film development, restoration and rescue within the laboratories of the Film Library.

UNAM’s Film Library Medal

The road before seeing a restored old movie on the big screen is long and elaborate. Knowing what is behind such an event highlights the importance of not missing out on the opportunity to attend their screenings.