Kodachrome color coupler history

[Heinz_Anderle]

As I was commissioned by my uncle to scan a selection of his favorite slides (among them Kodachromes from 1959/1960), I examined the scarcely available data to explain the differences (notable upon film scanner calibration) between the three film generations.

I have the booklet "Complete guide to Kodachrome II/Kodachrome X" by Patricia Caulfield, 2nd. ed., New York: Universal Photo Books 1964, with the density vs. exposure and the spectral absorbance graphs for both Kodachrome (I, 10 ASA, process K11), and the process K12-successors Kodachrome II (25 ASA) (and X, 64 ASA). The current Kodachrome 64 (and 25 and 200) require(s) K14 processing, and in the 1996/1998 data sheets (E-55 and E-88), Kodak has given the (same) spectral absorbance graphs for professional and amateur Kodachrome films.

I have read out the approximate absorbance maxima for each dye from the graphs for the following table:

dye K11 K12 K14

yellow 455 nm 435 nm 445 nm

magenta 525 nm 540 nm 540 nm

cyan 655 nm 640 nm 640 nm

It seems that for the transition from K12 to K14, only the yellow dyer had been changed.

It is noteworthy that the grain in today's Kodachrome 64 appears as fine as in Kodachrome (I), and that the almost 50 year old Kodachromes taken by my uncle appear as fresh as photographed yesterday.

 

[Ian Grant]

The grain might appear fine but the colours have disappeared well not totally but very significantly. I have my fathers Kodachrome slides and the deterioration is horrific. It's the worst I've seen of any colour process, and Kodachrome is supposed to be the most stable.

Ian

 

[AutumnJazz]

The grain might appear fine but the colours have disappeared well not totally but very significantly. I have my fathers Kodachrome slides and the deterioration is horrific. It's the worst I've seen of any colour process, and Kodachrome is supposed to be the most stable.

Ian

How were they stored?

You can't, for example, expect slides stored in a very humid atmosphere to be as good as if they were stored in a cool, dry, sealed box.

 

[dynachrome]

I saw Kodachrome slides in about 1990 which a family friend had taken in 1944 in Marseilles. They looked quite good. I wasn't there in 1944 so I can't say that they looked as good as new. The older processes like Duffay Color, pre-E-6 Agfachromes, Anscochromes and E-3 Ektachromes have not lasted nearly as well as Kodachrome.

 

[David Grenet]

If I recall correctly, the change in the yellow coupler was a change to CD6 which a certain Engineer who hangs around here had something to do with...

 

[Photo Engineer]

Yes, I worked on CD6 which was scheduled to be used in Kodachrome yellow, E6 and EP-3 processes, but the lawsuits by GAF and others ended that when Kodak lost. It is a long sad story which led to a product that did not meet our (my) expectation for stability in the early E6 and EP-3 products.

But, more properly, the peak dye density is useless without 2 other measurements. One is the half band width of the dye, and the other is the unit neutral forming capability (how much of each dye makes an 18% gray for example).

In addition, one should have the integral and analytical densities of the 3 layers in a neutral and in separation exposures.

More important than this all is the fact that Kodachrome couplers are NOT colored couplers. The term colored couplers can only be correctly applied to the orange masking couplers in negative films. If the coupler is colorless, then it is a coupler in name and fact, and nothing else.

PE

 

[Ian Grant]

How were they stored?

You can't, for example, expect slides stored in a very humid atmosphere to be as good as if they were stored in a cool, dry, sealed box.

They were stored in a slide box in a drawer in a bedroom, so not in a humid atmosphere. It's the earliest Kodakchrome slides that have faded badly, taken around 1959/1961, the rest aren't bad.

Ian

 

[nworth]

The complete details of process K-14 have been published, including the chemical formulas. I'm not sure if the detais of K-12 are available, but it dates from the period when Kodak started licensing Kodachrome processing. At least a few years ago, CD-6 was still available from a commercial chemical maker.

 

[Stephen Furley]

Some years ago Brian Coe used to give lectures at the now-closed Museum of the Moving Image, in London. He described the process for hand processing Kodachrome sheet film, I'm not sure if it was K11 or K12, many years previously. I don't think I'd want to do it myself.

 

[John Shriver]

Ian, were your Kodachromes processed by Kodak, or by someone else? Although if you're in the UK, they would probably be processed by Kodak, since the 1956 anti-trust settlement only un-bundled processing in the US.

I've never seen any signs of fading in Kodachromes. I've seen some processed by independent US labs (Technicolor, Berkey, etc.) that looked so-so, but I think they looked that way the day they were processed.

Ektachromes from 1959-61 are another issue entirely -- exceedingly fragile, a little too much heat and they fade to magenta real fast.

 

[Ian Grant]

Yes the Kodachromes were processed by Kodak UK, the ones that faded were a different version of the film to my fathers later ones. They were all shot with a Kodak Batam Colorsnap II, and the ill fated 828 film which later resurfaced in a cassette as Instanmatic - 126.

Ian

 

[Grant F Walker]

Kodachrome Processing can effect the colors lasting. How long before film processed? K11 & K12 is a complex process. A quality lab and personal is needed to check the chemicals.
Even when the chemistry is not correct, temp. of dyes too cold or hot there is pressure to run the film. We would sometimes have to run customers film anyway. When it came to Pro film it had to be processed with a test strip and returned to them with the film. Worked in a lab that processed film at 35ft per minute to 65ft. 1960/70. grant