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Topic: Does ester count as acetate?

Aaron Sisemore
Flaming Ribs beat Reeses Peanut Butter Cups any day!

Posts: 3061
From: Rockwall TX USA
Registered: Sep 1999

posted 05-11-2006 11:22 PM

quote: Frank Angel
we have been holding reels of tape up to the light to determine if it is poly or acetate since the early 80s.

However, in the case of open reel tape, its ACETATE that lets light shine through and polyester is totally opaque. (the reverse of 35mm film) I assume it has something to do with the base thickness of acetate vs poly.

quote: Frank Angel
So how come triacetate film is so susceptible to acidosis (VS) whereas not a single 10in reel of any of our acetate audio tapes, at least to my knowledge, has ever gone vinegar? I would imagine they are a different variation of acetate, no? I mean, physically they are very different animals.

I have see reels of acetate base tape go vinegar. Almost always the tapes were stored in plastic bags or in metal film-style cans.

Acetate base tape also degrades in much the same manner as its 35mm counterpart (especially if stored in less-than-ideal conditions: It will begin to shrink, causing the tape to curl and twist, making it difficult to maintain precision head contact. It also will get very brittle at this stage, making transport almost impossible in some cases without the tape breaking.

-Aaron

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John Hawkinson
Film God

Posts: 2273
From: Cambridge, MA, USA
Registered: Feb 2002

posted 05-11-2006 11:49 PM

Mark asks, "Now, where can I find an industry chart (maybe somewhere in the EK website) that confirms the meaning of the edge numbers?"

Kodak seems to've reorganized this stuff umpteen times since I last saw it, but I'm sure it is there somewhere. If you look at the Technical Data Sheet for 2383, under Identification, it says:

quote:

Processed film has magenta edgeprint (compatible with digital sound) with the following information printed along the length of the film: "2383/3383 (strip number) KODAK (date)".

2383/3383 Film is only available on ESTAR support, and is never on triacetate support.

Hopefully that's good enough for you. I think there's a more general set of explanations about edgecodes somewhere, though.

--jhawk

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Monte L Fullmer
Film God

Posts: 8367
From: Nampa, Idaho, USA
Registered: Nov 2004

posted 05-12-2006 03:33 AM

Hey Frank .. have any of those poly tapes have the backcoating where they get that 'sticky shed' syndrome to where you baking those reels of tape to get the moisture out of the backing material?

Do agree, seen acetate tape stored in an airtight situation where they do go to vinegar....

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Stephen Furley
Film God

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

posted 05-12-2006 07:49 AM

Triacetate base recording tape hasn't been available over here for a very long time; I think the last time I saw any on sale was probably in about the late '60s. The environmental conditions in some of the film vaults that I've seen have not been good, and this certainly wouldn't help. All other things being equal, recording tape should be more prone to this, as the presence of FE(III) ions, as in iron oxide tape coatings, tends to accelerate the process.

Does diacetate film base suffer from the same problem?

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John Pytlak
Film God

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

posted 05-12-2006 08:05 AM

Information about Kodak edgeprinting information is available on the Kodak website, and some of the sites that deal with film archiving:

EASTMAN KEYKODE Numbers

quote:
KEYKODE Identification Numbers

Triacetate Base - Estar Base - Keykode Number ID

Datecode Symbols

quote:
Until 1982, the date code was comprised of two symbols except for the following years:
1916, a circle; 1917, a square; 1918, a triangle; and 1929, a plus sign. For 1928 and
1948, three circles were used to identify the year of manufacture.
Date codes were repeated every twenty years until 1982. For example, the same symbols
appear on film manufactured in 1921, 1941, 1961 and 1981. In 1982, a third symbol was
added allowing for many more years of unique date coding.
Starting in 2001, date symbols will no longer be used for films without KEYKODE Numbers.
The actual date of manufacture will be part of the latent edgeprinting on these films.

KEYKODE Numbers

quote:
What are KEYKODE Numbers?
EASTMAN KEYKODE Numbers are machine-readable bar codes on Eastman film stock that exactly replicate the human-readable key number. They are printed every half foot and include a reference dot that identifies the frame to which each number applies.

http://www.sabucat.com/pdf/dcc.pdf

quote:
THESE ARE THE DATE CODE CHARTS FOR EASTMAN KODAK MOTION PICTURE FILM AND DUPONT FILM. READ THE SYMBOLS ON THE
EDGE MARKINGS OF THE FILM FROM LEFT TO RIGHT, AND COMPARE TO THE CHART. THIS WILL TELL YOU WHEN THE FILM WAS
MANUFACTURED AND WHERE. WHITE PRINTING TELLS THE INFORMATION ABOUT THE NEGATIVE, AND BLACK PRINTING TELLS THE
INFORMATION ABOUT THE POSITIVE PRINT. EXAMPLE: THE BLACK PRINTING READING LEFT TO RIGHT ON A PRINT OF "THE
PRODUCERS" IS " + + ". THE CHART TELLS US THAT THIS IS A PRINT STRUCK IN 1968, WHICH INDEED IS WHEN THE FILM WAS
RELEASED.

In addition, specific information about the edgeprinted product code is usually included in the technical datasheet for each Kodak motion-picture film on the Kodak website.

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