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Topic: Effect of Heat on Black-&-White Films

Manny Knowles
"What are these things and WHY are they BLUE???"

Posts: 4247
From: Bloomington, IN, USA
Registered: Feb 2002

posted 09-30-2002 06:19 PM

Antonio's thread "A matter of HEAT" reminded me that I had this question to ask:

I heard a story about a drive-in that was running Mel Brooks' YOUNG FRANKENSTEIN and they had to get another print because the heat from the lamp causes B&W film to swell. It wouldn't fit on the rewind platter after just one showing.

What's up with B&W film?

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Ken McFall
Jedi Master Film Handler

Posts: 615
From: Haringey, London.
Registered: Apr 2001

posted 09-30-2002 06:40 PM

Hi Manny,

I don't know all the tech stuff on this subject but from what I can remeber 'Real' B&W stock has a lot of silver in it and this absorbs heat and embosses the print in the shape of the apature plate.
I also seem to recall it got worse when Xenon lamps became the norm as they tend to be 'peaked' much more than carbon arcs were and the hot spots were torture to B&W stock.

It's definatly to do with heat absorbtion, someone else will have to give you the science on it.... All I can recall is being told to de focus the lamphouse to reduce hot spots and drop the current as well.

At my age memory can play trick so if all of this is hot air I'm sure someone will let me know

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Stephen Furley
Film God

Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002

posted 09-30-2002 06:57 PM

The silver in a black and white emulsion absorbs infra red more than the dyes n a colour one, therefore it tends to overheat, and distort.

In the days before halogen lamps, most 16mm projectors used 750W tungsten lamps, but could also take a 1000W version for larger screen sizes. However, the use of these was not recommended with black and white film, for this reason.

Triacetate safety film is not very tolerant of overheating, and buckles quite easily. Polyester is much more resistant to heat, but, of course, it is still possible to damage the emulsion if it gets hot enough. Nitrate seems to be somewhat more resistant to heat than triacetate, but of course, there are other very good reasons not to overheat nitrate film.

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 10-01-2002 01:32 PM

Yes, silver-image B&W films absorb significant infrared energy, and are therefore more prone to heat-related effects than color films (most dyes are relatively "transparent" to infrared energy):
http://www.kodak.com/US/en/motion/newsletters/pytlak/fall97.shtml
http://www.kodak.com/US/en/motion/newsletters/pytlak/winter97.shtml

Color prints with "silver retention" processes also contain some silver in the image area, and are more prone to heat-related effects:
http://www.theasc.com/magazine/nov98/soupdujour/pg1.htm

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: +1 585 477 5325 Cell: +1 585 781 4036 Fax: +1 585 722 7243
e-mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

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Bill Gabel
Film God

Posts: 3873
From: Technicolor / Postworks NY, USA
Registered: Jan 2002

posted 10-01-2002 02:05 PM

Back in 1993, the GCC theatre I was working at opened "Schindler's List". We opened it on three screens. The main house was a Century
SA (water cooled gate) with a Christie 4K lamphouse and the other two screens were Century SA's with a Christie 1.6k lamps. If you remember the print, it was Black & White with Color scenes slugged into the movie. Universal paid for a studio call for the TAP setup. If you
ran this picture as TAP had you set it up. And your projector was not
water cooled. About two hours into the picture on the non water cooled
projectors. We would hit the color scenes it would go out of focus.
So every time on those projectors, we would get a call from the
downstairs that we were out of focus. This 5 screen theatre, the main houses were a twin and across the street was the tri-plex house.
So by the time you got across the street, it was back into the B&W
scenes. This film opened on I think a Wednesday, by Thursday Universal
had sent three more prints to test. By Friday I had a total of seven
prints built-up. We found out that TAP never thought about projectors
that were not water cooled and running a 3 hour+ B&W picture with
color scenes slugged in on a platter.

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 10-01-2002 02:21 PM

I wrote about the "Schindler's List" projection issues in the October 1994 issue of Kodak's "Film Notes for Reel People":
http://www.film-tech.com/manuals/H5034.pdf

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Frank Angel
Film God

Posts: 5305
From: Brooklyn NY USA
Registered: Dec 1999

posted 10-01-2002 10:38 PM

John,

Whatever happened to Film Notes for Reel People? It was a great publication. In the last days it seemed to come irregularly and then it just stopped. I've got them bound together. Every so often a film student shows some interest in the theatre and the booth and I shove the binder in his hand and tell him if he's serious, to read it from cover to cover. I wish it were back, even if it were printed only when enough new material accumulated.

Frank

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John Pytlak
Film God

Posts: 9987
From: Rochester, NY 14650-1922
Registered: Jan 2000

posted 10-02-2002 07:24 AM

"Film Notes for Reel People" evolved into "Cinema Notes". Every few years, a subscription renewal card was sent with the publication. If you forgot to renew, your free subscription lapsed.

Kodak began publishing "Cinema Notes" on the Kodak website a few years ago. Past "Pytlak's Practical Projection Pointers" articles are available on-line, and more are planned. Please let me know what topics are of interest:
http://www.kodak.com/US/en/motion/newsletters/pytlak/

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