View Full Version : Kodachrome Secrets

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Photo Engineer
06-28-2007, 04:44 PM
This does highlight two important points.

1. There are no secrets to Kodachrome. It is free for the taking if you can get the chemicals and it can be home processed.

2. There is no competition nor interest in it by anyone but Kodak, and the customer base is decreasing. (it is not the other way around as I have pointed out before - Kodak even developed that 400 speed Kodachrome and was met with frank indifference in the market to any 'improved' Kodachromes in the late 80s)


Earl Dunbar
06-28-2007, 09:31 PM
That (no interest in improved/400 Kodachrome) is really sad.

06-29-2007, 09:44 PM
That makes perfect sense, and is likely the reason for the patent being abandoned, as the first maintenaince fee is due at 3.5 years from issuance. The fees increase as the patent ages, so it would be logical for EK to review each patent for usefulness before paying the fees.

Thanks for that info. I have to admit that I wasn't aware there were maintenance fees on patents. That puts it into a whole different light.


06-29-2007, 09:51 PM
So what can you tell us about the manufacturing? How many layers make up Kodachrome?

Also, I heard stories about the process being a nightmare to monitor -- not only temperatures that have to be held sometimes to +/- 0.05 degrees, but pH, specific gravity, etc. One story was that you essentially had to have a degreed chemist on staff to run a line.

I also got the impression that Kodak didn't sell the chemicals "ready mixed", that you essentially had to compound each solution.

And, finally, no one else has mentioned the coincidence of the last name of the co-author of USP 3,658,525...



06-29-2007, 10:16 PM
And, finally, no one else has mentioned the coincidence of the last name of the co-author of USP 3,658,525...

That patent describes Kodachrome processing. I must admit I wouldn't want to have to make those chemicals from scratch, but then I'm not a chemist either.

06-30-2007, 12:14 AM
I also got the impression that Kodak didn't sell the chemicals "ready mixed", that you essentially had to compound each solution.

Between 1954 and 1961 a legal case was made against Kodak in the the USA under the Sherman act. Several issues were brought up, the main being selling Kodachrome and Kodacolor there including processing, thus keeping other businesses out of the business in a substantial way. Within a seven year period Kodak had to change the situation. Which meant in the Kodachrome case licensing finishers to process this film and enabling them practically to do so. To my understanding this meant selling them chemical kits, though I haven’t found anything more substantial on the latter issue at a short glance at my literature.

Photo Engineer
06-30-2007, 09:39 AM
Kodak does indeed sell a Kodachrome kit, but it is a complex mixing job I understand. Our labs mixed it from scratch.

The color developers are high pH and contain both developer and coupler. Therefore, as they keep they turn cyan, magenta and yellow. What else. And, control is a beast with the system.

It must run constantly with good replenishment or it goes out of control and drifts. It takes over 1 hour to process it, but it was routinely done by hand at Kodak.

The film has 9 emulsions and at least 6 layers, but I've forgotten most of it. I do remember that it is very very thin and is essentially a set of B&W coatings layered on top of each other that respond to the process to create the color. You can duplicate this by making tricolor positives on 3 sheets of any good pan film, and running them through a Kodachrome type process and then sanwiching them together.

In that case, the developers can be simple C41 or E6 type developers (depending on pos or neg) and the couplers can be rather simple organic chemicals just for demo purposes. (If you don't want exact color and good dye stability). This is a straightforward process to accomplish.

Yes, I am one of the co-inventors of the CD-6 used in Kodachrome. It was also to be used in E6 and in RA (EP-2 originally), but lawsuits again intervened from Ansco and Pavelle, and so the plans were cancelled for everything but Kodachrome.

The dye stability was much better with CD-6 under some conditions tested and the development reaction was faster. But, here we are without it now due to those law suits which claimed that Kodak changed the process to hurt competition. Well, our concern was not the competition, but rather the quality of the final image. We were very discouraged over that.


06-30-2007, 10:30 AM
In spite of the tricky development of a Kodachrome kind of film and though having gained free access to Agfa patents and knowledge, Ilford decided after WWII just to go the former way concerning their ideas on developing an own three-layer colour film.
They stated that they were not able to synthesize the necessary ballasted couplers, but were able to make or obtain those more simple type couplers used in a non-substantial film. Further they wanted to produce 8mm cine reversal film and a non-substantial film promised finer grain to them. Somehow they achieved to get around the Kodachrome patents and released in 1948 their non-substantial three-layer “Colour Film `Dī” (10 ASA).

07-29-2007, 09:57 AM
Concerning patent maintenance fees, as I recall (having once actually paid a fraction of the fee out of my own pocket) the cost is only a few hundred dollars, so I doubt that cost of paying the maintenance fee was a significant factor in Kodak's decision to abandon the patent.

Photo Engineer
07-29-2007, 10:15 AM

Consider the fact that Kodak has thousands of patents, and they must be maintined in many countries. This is a significant expenditure.

It was one patent among many that were weeded out. The reason being lack of interest and the fact that Fuji quit making a Kodachrome material so no one was going to try to duplicate the patent.

The color paper patent regarding CD6 was not abandoned.