Film base is a transparent substrate which acts as a support medium for the photosensitive emulsion that lies atop it. Despite the numerous layers and coatings associated with the emulsion layer, the base generally accounts for the vast majority of the thickness of any given film stock. Historically there have been three major types of film base in use: cellulose nitrate, cellulose acetate (cellulose diacetate, cellulose acetate propiarate, cellulose acetate butyrate, and cellulose triacetate), and polyester (sometimes called Estar). See: transparency (optics) alpha compositing GIF#Transparency transparency (overhead projector) market transparency transparency (telecommunication) transparency (computing) For X11 pseudo-transparency, see pseudo-transparency. ... The word substrate can mean the following: In biochemistry, a substrate is a molecule which is acted upon by an enzyme. ... Photosensitivity is the amount to which an object reacts upon receiving photons of light. ... A. Two immisicble liquids, not emulsified; B. An emulsion of Phase B dispersed in Phase A; C. The unstable emulsion progressively separates; D. The (purple) surfactant positions itself on the interfaces between Phase A and Phase B, stabilizing the emulsion An emulsion is a mixture of two immiscible (unblendable) substances. ... Film stock is the term for photographic film on which films are recorded. ... Nitrocellulose (Cellulose nitrate, guncotton) is a highly flammable compound formed by nitrating cellulose (e. ... Cellulose acetate, first prepared in 1865, is the acetate ester of cellulose. ... Triacetate also known as cellulose triacetate, is manufactured from cellulose and acetate. ... For the film, see the article Polyester (film) Close-up of a polyester shirt SEM picture of a bend in a high surface area polyester fiber with a seven-lobed cross section Polyester is a category of polymers, or, more specifically condensation polymers, which contain the ester functional group in...

Nitrate

Nitrate film base was the first base commercially available, thanks to celluloid developments by John Carbutt, Hannibal Goodwin, and Eastman Kodak in the 1880s. Unfortunately, nitrate also had the drawback that it was extremely flammable (being essentially the same chemically as guncotton) and decomposed after several decades into a no less flammable gas, leaving the film sticky and goo-like. As this happened, the likelihood of auto-ignition increased even further. Projection booth fires were not uncommon in the early decades of cinema if a film managed to be exposed to too much heat while passing through the gate, and several incidents of this type resulted in audience deaths by flames, smoke, or the resulting stampede. While an accident of this sort was famously recreated in Cinema Paradiso, the risk was certainly not fictional; in one instance, the Laurier Palace Cinema in Montreal was the site of a fire on January 9, 1927 that occurred during a kids' film program and resulted in 77 children between the ages of 4 and 18 killed. 1978 was a particularly devastating year for film archives when both the National Archives and George Eastman House had their nitrate film vaults auto-ignite. Eastman House lost the original camera negatives for 329 films, while the National Archives lost 12.6 million feet of newsreel footage. Because the ignition of cellulose nitrate creates its own oxygen, nitrate fires can be very difficult to extinguish. The US Navy has produced an instructional movie about the safe handling and usage of nitrate films which includes footage of a full reel of nitrate film burning underwater. The base is so flammable that intentionally igniting the film for test purposes is recommended in quantities no greater than one frame without extensive safety precautions. Most nitrate films have been converted in recent decades to polyester copies, and original nitrate prints are generally stored separately to prevent a nitrate fire from destroying other non-nitrate films. Sometimes nitrate collections are even split up into several different fireproof rooms to minimize damage to a collection in toto should a fire occur in one part. Usually a theater today needs to pass rigorous safety standards and precautions before being certified to run nitrate films; this includes a fireproof projection booth, fire chambers surrounding the feed and takeup reels, and several fire extinguishers built into the projector and aimed at the film gate should a trigger piece of fabric ignite. Nitrate film is classified as "dangerous goods", which requires licenses for storage and transportation. Celluloid is the name of a class of compounds created from nitrocellulose and camphor, plus dyes and other agents, generally regarded to be the first thermoplastic. ... The Reverend Hannibal Goodwin (1822-1900), a Episcopal minister at the House of Prayer in Newark, New Jersey patented a method for making transparent, flexible film out of nitrocellulose. ... To meet Wikipedias quality standards, the remainder of this article may require cleanup. ... Nitrocellulose (Cellulose nitrate, guncotton) is a highly flammable compound formed by nitrating cellulose (e. ... The autoignition temperature of a substance is the lowest temperature at which it will spontaneously combust in a normal atmosphere, without an external source of ignition, such as a flame or spark. ... Categories: Stub | 1989 films | Italian films ... City motto: Concordia Salus (Latin: Well-being through harmony) Province Quebec Mayor Gérald Tremblay Area  - % water 366. ... More than one country maintains a national archive: The Canadian Library and Archives Canada The New Zealand Archives New Zealand (formerly National Archives) The United States National Archives and Records Administration The United Kingdom National Archives This is a disambiguation page — a navigational aid which lists other pages that might...

Acetate

Despite the dangers of the nitrate film base being known practically since its development, it was used in virtually all major motion pictures prior to 1952, when Kodak completed a four year conversion program to the sole manufacturing of acetate base film stocks. Kodak actually began working with acetate "safety film" as early as 1909, and started selling it in 1910 for 22 mm film. Acetate has always been used with 8 mm and 16 mm formats, as they were originally created for amateur home movie usage, and generally was used for most sub-35 mm formats to minimize risk to the general public. (Several formats, such as 17.5 mm, which were often re-slit from 35 mm were nitrate, however. One of Kodak's reasons for choosing 16 mm instead of 17.5 mm for a standard amateur format width was specifically to prevent nitrate re-slits from being used in home movies.) Acetate also is the only base which has been used with color negatives. All motion picture camera negatives are now shot on acetate film because it is safer than nitrate but not as strong as polyester bases, which may damage the camera rather than the film should a jam occur. Acetate film does not burn under intense heat, but rather melts, causing a bubbling burn-out effect - this can be seen simulated in films such as Persona or Velvet Goldmine, or, if one is unlucky, in actuality during a film screening where the a frame becomes stuck in the projector's film gate! Acetate films are also subject to degradation over time, however, as the acetate catalyzes into acetic acid vapors, causing shrinkage of the film base and acidification of the base and eventually the emulsion. This is known as vinegar syndrome, because the film begins to smell like vinegar due to the acetic acid presence. For other uses see film (disambiguation) Film refers to the celluliod media on which movies are printed Film — also called movies, the cinema, the silver screen, moving pictures, photoplays, picture shows, flicks, or motion pictures, — is a field that encompasses motion pictures as an art form or as part of... 8 mm may be referring to: 8 mm film, or its replacement Super 8mm film The American film entitled 8mm about a private detective verifying the existence of a snuff movie. ... (Redirected from 16 mm) 16mm film was initially created in the 1920s as an inexpensive amateur alternative to the conventional 35 mm film format. ... Persona is a movie by Swedish director Ingmar Bergman, released in 1966, and featuring Bibi Andersson and Liv Ullmann. ... Velvet Goldmine (1998) is a film directed and co-written by Todd Haynes. ... Vinegar syndrome [= VS] is a problem with cellulose triacetate film, in which it degrades and releases a smell resembling that of vinegar. ...

Polyester

Polyester is the most recent film base to have been developed, and was first used for specialized photography applications in 1955, but it was only in the 1990s that it became overwhelmingly popular for motion picture prints. It is highly preferable for post-production, exhibition, and archival purposes because of its flexibility, strength, and stability. Its strength is sometimes also a weakness, however, in that polyester base films are so resistant to breakage that they are often more likely to break the film equipment should a jam or extra tension occur. Movie cameras therefore do not use this base for shooting the original camera negative, as it is vastly preferable and less costly in time and money for the film to break instead.

Identifying a film base

There are several factors which can aid in identification of the film base of a roll of film. Many are not 100% conclusive, and it is best to use a selection of these to positively verify a film base.

• The edge printing will often say "nitrate" or "safety" on it.
• No Kodak film manufactured after 1951 is nitrate, and no film of any kind is polyester before 1955.
• Deterioration artifacts are distinct between nitrate (noxious nitric acid gas; amber discoloration; soft, sticky, or powdery film) and acetate (acetic acid gas, red or blue discoloration, shrinkage, brittleness, presence of bubbles or crystals).
• Polyester shows red and green interference colors when viewed through cross-polarized filters.
• A solution of diphenylalanine and sulfuric acid will turn nitrate deep blue.
• A highly controlled burn of one frame of nitrate will result in a bright yellow flame which consumes the film almost completely. (ONLY PERFORM WITH THE HIGHEST OF CAUTION!)
• Nitrate film is soluble in a variety of solvents - namely methyl alcohol, ethyl, and ether.
• Float testing of the specific gravity of the base in trichloroethylene should cause nitrate to sink, acetate to float, and polyester to remain around the middle. However, this can be complicated by impurities and deterioration factors.
• Light aimed through the back of a roll of film will shine through if it is polyester, but will not if it is acetate.

References

• Wilhelm, Henry and Carol Brower. The Permanence and Care of Color Photographs: Traditional and Digital Color Prints, Color Negatives, Slides, and Motion Pictures, Chapter 19. Grinnell, Iowa : Preservation Publishing Company, 1993.
• Film Preservation Handbook
• Kodak Chronology of Motion Picture Films
• NEDCC Technical Leaflet - A Short Guide to Film Base Photographic Materials: Identification, Care, and Duplication