I'm aware of a number of different Kodak filmstocks:

Older Eastman -- The sort that fades to red.
SP -- Better fade characteristics, but tends to fade to brown.
LP -- a short-lived low-fade filmstock
LPP -- Low fade

However, occasionally I run across a film with the designation "4B" printed in the margins. Some claim that this is a particular type of filmstock, but I've seen prints labelled "4B" from the early 1970s through the late 1980s -- in other words, the filmstock spans the transition to low-fade stock, and I've seen 4B prints that are faded, as well as 4B prints with no fade whatsoever.

My question for John Pytlak (or anyone else who might know) is, does "4B" indicate a particular emulsion formulation, or does the designation mean something else, such as a production or distribution code?

The "Chronology of Kodak Motion Picture Films" lists the history of Kodak film types:
http://www.kodak.com/US/en/motion/about/chrono1.shtml

Here's information on Film Identification:
http://www.kodak.com/country/US/en/motion/support/h1/identification.shtml

The "SP" referred to the first film designed for the "Short Process" ECP-2 process, EASTMAN Color SP Print film, 7/5383. For higher temperature Process ECP-2. For greater release printing efficiency in larger labs. Quality similar to 7/5381 with which it will co-exist. Discontinued 1983

The era of "low fade" Kodak print stocks began in 1979, with the introduction of EASTMAN Color LF Print film, 7378 which had improved cyan dye post processing keeping. Process ECP. Markedly improved cyan dye dark-keeping stability. It was discontinued January, 1982.
EASTMAN Color LFSP film, 7379 was the same as 7378 except for Process ECP-2. Markedly improved cyan dye dark-keeping stability. Discontinued 1983. These two films sold for a slightly premium price, and so were not widely used for general release prints.

In 1982, EASTMAN Color Print film, 7/5384 was introduced. It had improved cyan dye dark keeping. Process ECP-2A. Replaced 7/5381, 7/5383, 7378, 7379. In SMPTE Journal December 1982 and BKSTS Journal August 1983. This is the film that had the "LPP" designation.

In 1988, EASTMAN Color Print film, 7/5384 was modified to eliminate need of formalin in stabilizer, which had been required to stabilize the magenta dye. Process ECP-2B has no formalin.

In 1993, EASTMAN EXR Color Print Film 5/7386 replaced 5/7384. Process ECP-2B.

All the above films were available on ESTAR base as well, with a rem-jet antihalation layer, but strong and durable polyester base did not become popular for 35mm release prints until the mid 1990's.

In 1997, SO-886 was the first print film featuring an ESTAR base that had a proprietary transparent conductive antistatic layer with solid particle antihalation dyes that were removed during processing.

In 1998, KODAK VISION Premier Color Print Film 2393 and KODAK VISION Color Print Film 2383 were introduced, featuring additional improvements to the antistatic ESTAR base, and new emulsion technology:
http://www.kodak.com/US/en/motion/products/lab/2393.shtml
http://www.kodak.com/US/en/motion/products/lab/2383.shtml

The current print process (ECP-2D) no longer requires the complex rem-jet removal step.

It is well known that improper processing and storage conditions often play a significant role in dye fading. For example, insufficient washes may leave residual thiosulfate (fixer) in the film, or result in the incorrect emulsion pH. Work by the Image Permanence Institute clearly shows the advantages of cool and dry storage conditions:

http://www.rit.edu/~661www1/sub_pages/page3a.htm
http://www.rit.edu/~661www1/sub_pages/frameset3.html

Nitrate and acetate films should also be stored in vented containers, to reduce buildup of acid vapors that cause base deterioration (e.g., "vinegar syndrome") and greatly increase the rate of dye fading. If sealed containers are used, Molecular Sieves will adsorb excess moisture and acids:
http://www.kodak.com/country/US/en/motion/support/technical/molecular.shtml

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

Other than the codes I provided on the Kodak website, earlier color print films may not have unique edgecodes for each film type. Until a few years ago, the edgecode was printed on print film during slitting, using a photographic stencil that could not be easily changed between product runs. So other than common information like strip number and manufacturer name, different film types could be printed with the same code if they were slit on the same slitter.

I recall that a few years ago, some film was made WITHOUT ANY EDGECODE for a few months, until Kodak developed the technology and procedures to print the edgecode in a way that would not interfere with SDDS or Dolby Digital tracks. As you know, the edgecode is now printed in magenta dye so as not to interfer with the red LED reader used for SDDS, which "sees" only the cyan dye.

Today, the edgecode is printed with computer-controlled green lasers, so the code is unique for every roll of film manufactured, allowing us to track the batch through the entire manufacturing process.

Here is a typical edgecode today:

2383 603 074 0 27 20 K.ODAK 2001

2383 is the film type (KODAK VISION Color Print Film)
603 is the emulsion batch
074 is the roll number
0 27 20 is machine tracking information
K.ODAK tells who made it
2001 is the year of manufacture

Other film manufacturers put much less (or even no) information on their print film, despite the advances in edgeprinting technology.

Here's a link to more information:
http://www.kodak.com/US/en/motion/support/h1/identification.shtml

------------------
John P. Pytlak, Senior Technical Specialist
Worldwide Technical Services, Entertainment Imaging
Research Labs, Building 69, Room 7525A
Rochester, New York, 14650-1922 USA
Tel: 716-477-5325 Cell: 716-781-4036 Fax: 716-722-7243
E-Mail: john.pytlak@kodak.com
Web site: http://www.kodak.com/go/motion

That means that after all the nitrate and acetate has shrivelled into dust, future generations of archivists will be deprived of the pleasure of looking up tables full of cryptic symbols whenever they want to date an element. Takes all the fun out of it if you ask me!

I don't think it was some sort of conspiracy to use a secret code for the date. The code symbols have been public for quite some time. Rather, I think it was due to a limitation of the old edgeprinting methods that used photographic stencils that were hard to change, and had limited message capability. Edgeprinting technology used by Kodak has come a long way, and we can now track the film down to every individual roll.

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