Oxford Duplication Centre Ltd

    FILM SUPPORTS Like photographic prints and glass negatives, film-based media are composite objects, consisting of a film support and a binder/emulsion layer with an image-forming or recording substance suspended in it. Film has been used as a support for many different types of media since the late 19th century, including various types of still photography film, slide film, microfilm, amateur movie film (8mm and 16mm), and motion picture film. Three types of film have been used as supports: nitrate, acetate, and polyester films (with the latter being the most stable). Many modern film-based media use a polyester film base, but not all. The characteristic deterioration of these films will be discussed in this section, along with typical deterioration mechanisms of the binder and image-forming materials. 1 NITRATE FILM Nitrate film was invented in the late 19th century in response to the need for a more lightweight and less fragile support for photographic negatives. The fir...

Acetate Film Base Beginning in the mid-1920s, highly flammable nitrate film was slowly replaced with cellulose acetate film base (cellulose diacetate, cellulose acetate propiarate, cellulose acetate butyrate and cellulose triacetate).  It became known as "Safety" film. Despite this name, cellulose acetates do have stability problems. Like cellulose nitrate, the deterioration of cellulose acetate is autocatalytic: once deterioration has begun, the degradation products induce further deterioration. It affects the plastic support of acetate film, causing it to become acidic, to shrink, and to give off of acetic acid producing a vinegary odor.  A useful tool in helping determine the amount of acid vapor present, and gain an overview of the condition of acid vapors in an entire collection are "A-D Strips" (acid-detecting strips). They are acid-base indicator papers, which turn from blue to green to yellow in the presence of acid, and measure the extent of the acetate bas...

INTRODUCTION New technologies are adopted based on their advantages, and disadvantages are considered later or sometimes not at all. Preservation often involves working to mitigate those disadvantages and, in the case of photography, this means working to increase the stability of inherently unstable materials.  There are three broad types of film-based photographic materials: cellulose nitrate, cellulose acetates, and polyester. These materials have been used as a support for negatives, positive transparencies, motion pictures, microfilm, and other photographic products. Unfortunately, cellulose nitrate and cellulose acetates are unstable. The products of their degradation can severely harm and even destroy photographic collections, in addition to posing serious safety hazards.   IDENTIFICATION Nitrate Film Base In August 1889, Eastman Kodak began selling the first photographic negatives on cellulose nitrate flexible film support. This innovation was the foundation of an...