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Q: Film Burn ( Answered,   0 Comments )
Subject: Film Burn
Category: Science > Chemistry
Asked by: msteinberg-ga
List Price: $10.00
Posted: 02 Jun 2003 14:30 PDT
Expires: 02 Jul 2003 14:30 PDT
Question ID: 212137
What causes film to bubble and boil and eventually burn when caught in
a projector and how can it be recreated without the projector?  What
we are really trying to do is recreate the plastic burning but with
bubbling which apparently doesnt happen when burning just plastic.  We
know we need to treat the plastic but with what?
Subject: Re: Film Burn
Answered By: clouseau-ga on 02 Jun 2003 15:11 PDT
Hello msteinberg,

Thank you for a very interesting question.

I found a good part of the answer at a cached page for CinemaScope


In CINEMA PARADISO, one of the key symbolic elements is fire; it
causes some dramatic sequences with life-changing results to Alfredo
the projectionist. It just so happens that although fire works very
nicely as a creative tool for director Giuseppe Tornatore, its
potential danger in the projection booth is grounded in good
scientific fact.

Nitrate base film was the first material used for theatrical motion
picture stock since the industry began in the silent era. Many years
of research went into finding just the right compound that could be
used for the film base. Nitrate film seemed to have all the physical
properties that made it ideal: flexibility, the ability of the picture
emulsion (the gellatin material that contains the actual image) to
adhere to it, light weight, and its ability to transmit light. It had
all the right properties save wasn't inert -- rather, it
was highly volatile in the presence of heat; it had a tendency to
explode into uncontrollable flame.  The fact that the very nature of
the projection equipment required that this nitrate film would have to
pass in front of an extremely hot light source needed to produce a
bright theatre picture, made the problem doubly vexing.

The potential for fire in theatre projection was always a very real
possibility. Regulation after regulation were written to govern how
the nitrate film should be handled in the projection booth so that it
would present the least danger of igniting. As a result, projection
booths became fireproof fortresses; their walls, ceiling, and floors
by law had to be constructed of double thick brick or stone block and
the doors of double steel with automatic closures that would swing
them closed if a fire were to start in the booth. Likewise, all the
projection windows or "ports" were to have shutters that slam shut in
the presence of a rise in temperature. In the days before
air-conditioning, many shows stopped abruptly because the fire fuse
link would give way and the shutters would drop in front of the booth
ports in the middle of the show1!   The idea was, that if the nitrate
film "flashed" (that's how it burns - it's a cross between "ignite"
and "explode"), the projection booth and the fire would effectively be
sealed off from the rest of the theatre and the patrons (presumably
creating a "projectionist flambe" in the process)...."

So the flash is caused by the nitrate base of the film stock.

Interesting article. It continues with the history and precautions of
handling film safely.

"...In the mid-forties it was the Eastman Kodak Company who introduced
a new film stock which they called "safety film." Many people
incorrectly assume that this film will not burn; safety film does burn
- but it does not explode like nitrate film. It doesn't burn once the
heat source is removed. Although Kodak developed safety film
specifically for use in the amateur film market,which could not be
expected to grow significantly if the film being offered for sale
would burst into flames if you looked at it the wrong way. The new
triacetate safety film quickly began to replace nitrate film in the
theatrical industry as well..."

So modern film will not exhibit these properties.

So, to recreate this effect, you will need nitrate based film stock
and a heat source.

The National Museum of Photography says:

"...Cellulose Nitrate was first used as a base for photographic roll
film by George Eastman in 1889 and was used for photographic and
professional 35mm motion picture film until the 1950s. It is highly
inflammable and also decomposes to a dangerous condition with age.
When new, nitrate film could be ignited with the heat of a cigarette;
partially decomposed, it can ignite spontaneously at temperatures as
low as 120 F (49C). Nitrate film burns rapidly, fuelled by its own
oxygen, and releases toxic fumes...

...Nitrate movie film was made mostly in the professional 35mm gauge,
though in the 1890s and the early years of this century some amateur
film stocks, such as 17.5mm, were cut down from 35mm film.

8mm, Super 8, 9.5mm and 16mm movie film was always manufactured with a
safety (non-flammable) base, as were the earlier Edison 22mm and Pathé
28mm films. 35mm safety movie film was made from 1908 onwards but was
not widely used by the cinema industry until the mid-1950s...

...Only a few institutions are licensed to project nitrate film. YOU
view and preserve the images on the film is to copy it onto safety
film. The following laboratories copy nitrate film:

Film and Photo, 13 Colville Road, South Acton Industrial Estate,
London W3 8B.
Tel: 020 8992 0037

Hendersons Film Laboratories, 18-20 St Dunstan's Road, South Norwood,
London SE25 6EU. Tel: 020 8653 2255

Soho Images, 71 Dean Street, London W1V 5HB. Tel: 020 7437 0831..."

You might wish to contact these companies to see if you can obtain a
small sample of nitrate based film for your project.

This page has a little more information:

"...Nitrate Film is a type of movie film material that is made of
cellulose nitrate and quickly deteriorates when stored in less than
ideal situations. This type of film material is also known as
cellulose nitrate or nitrocellulose. Cellulose nitrate was discovered
when nitric acid was mixed with cotton, a naturally occurring
cellulose (early.htm). The function of cellulose nitrate is to provide
a flexible base on which to fix an image. A strip of movie film is
essentially composed of two layers: base and emulsion..."

Searching a bit further, I find that this is also used in furniture

Bali Exports:

"Bali Exports Co. uses a variety of finishing processes depending upon
the type of furniture being manufactured.  The most common finish for
Antique Reproduction furniture that is made from mahogany is a finish
called "NC" (Nitrocellulose).

Nitrocellulose is a very strong and durable finish that gives the
furniture a very tough outer shell as well as a beautiful shine and

So, coating a modern film stock with this finish *might* produce the
effect you seek.

It appears to be available from Nobel Enterprises:

There is also an interesting page on nitrocellulose with a viewable
movie on igniting it.

Finally, here are 31 companies that supply nitrocellulose:

Search Strategy:

film +bubble OR burn +projector
nitrate +film
"cellulose nitrate" OR nitrocellulose

I trust my research has provided your answer. If a link above should
fail to work or anything require further explanation or research,
please do post a Request for Clarification prior to rating the answer
and closing the question and I will be pleased to assist further.


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