Chemistry in Pictures: Cinema protetto

You may remember the scene in the classic film Cinema Paradiso, directed by Giuseppe Tornatore, where a reel of cellulose nitrate film ignites in Alfredo’s face, leaving him permanently blind. Known as safety film, cellulose acetate started to replace cellulose nitrate in the 1920s due to its nonflammable properties. Nowadays, a huge amount of European cultural heritage can be found in cellulose acetate movie stock produced during the 20th and 21st centuries. Although safe, cellulose acetate is chemically unstable and very susceptible to degradation, and a century of visual and audio memories is in danger of being lost. This microscope image shows a cross section of cellulose acetate film, containing a movie produced between 1950 and 1960, under polarized light. The whitish particles at the surface are triphenyl phosphate, a plasticizer used to make the film flexible. Plasticizer migration causes the polymers’ physical properties to change and renders the images indecipherable. The European project NEMOSINE provided this historical sample to the Department of Conservation and Restoration at NOVA University Lisbon. To avoid the deterioration of this cultural heritage, NEMOSINE has two main goals: to fully understand the degradation mechanisms and to develop innovative packaging that will extend the polymer’s lifetime and provide an alternative to energy-intensive cold storage.

Submitted by Artur Neves

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