Home About ANICA Search News Contributions Contact Us Members' Corner

ANICA Home > Assessment Guidelines> Identification of cellulose acetate in collections


Identification of cellulose acetate in collections

The identification of cellulose acetate within collections is a first step in planning how to manage this material. A range of formats in Australian collections are on cellulose acetate. These include: sound material, motion picture film, microfilm, photographic negatives, and microfiche, and may include other less common formats such as graphic arts films and overlay transparencies.

Although this Guide is limited to identifying documentary based formats, it is worth noting that cellulose acetate was used for a wide range of collection items including dice, casino chips, glasses frames, and imitation tortoiseshell goods. These are all subject to the same type of degradation and should be cared for appropriately.

Film Collections

Film base materials for motion picture film, microfilm, microfiche and photographic negatives are often difficult to differentiate from each other. All films in their undeteriorated state tend to fulfil the basic requirements of being clear and flexible, and identification of the major polymer involved can be complex.

While a variety of film bases have been used throughout the past century, only three of these form the major part of most collections. They are:

  • cellulose nitrate;
  • cellulose acetate; and
  • poly (ethylene terephthalate) (commonly referred to simply as 'polyester').

Other bases, such as polycarbonate and polystyrene, were never used to any great extent and are quite rare. The cellulose acetate category encompasses the mixed esters of cellulose acetate butyrate and cellulose acetate propionate as well as cellulose diacetate and triacetate. All the acetates have similar deterioration characteristics and preservation requirements, and can be considered as a group.

The following sections will provide a practical guide to the steps necessary for the identification of film within collections.

Sound collections

In the case of sound collections, the principal materials used for the base are cellulose acetate, polyvinyl chloride (PVC) and polyester. (Polyvinyl chloride is another unstable carrier, which releases hydrochloric acid as it deteriorates). So called 'Acetate Discs' are really based on a modified nitro-cellulose compound, and are not cellulose acetate.


previous / next / Back to Contents page

Home About ANICA Search News Contributions Contact Us Members' Corner