Technology: Perfect preservative for canned film

时间:2019-03-02 01:02:06166网络整理admin

The ‘vinegar syndrome’ that rots movie film stored in sealed cans has been beaten at last. Researchers working for Kodak, which made most of the film now in storage, have found a simple way of mopping up the chemical that destroys the film base and makes colour film fade. The vinegar syndrome was discovered in the late 1940s, as the movie industry began to use film with a cellulose triacetate base. Although all films and copies of old films are made on this base, no one had a cure until now. Film is stored in a sealed can to protect it from dirt and physical damage. But the can traps moisture in the film and the air. It also concentrates traces of acetic acid that the film releases as it ages in a moist environment. The acid then acts as a catalyst, accelerating the decomposition of the base and releasing more acid in a vicious circle of self-destruction. In a separate process, any moisture sealed inside the can breaks down the dyes present in colour film, especially the yellow dye. The release of acid accelerates this fading. Although silica gel absorbs moisture, it does not absorb the acid chemicals. Now researchers at Kodak’s headquarters in Rochester, New York, found the simple trick of putting some zeolite (a form of sodium aluminosilicate) in the can with the film. The zeolite absorbs any water inside the can’s atmosphere and also any acetic acid, thus stopping the decomposition. It is packaged in a semipermeable polyethylene jacket to prevent it touching and soiling the film. Kodak began testing the system last year with 10 old movies, including a 1936 negative of Broadway Melody. The company is convinced that the simple treatment works,