The Na+ and K+ ions are very much alike except for size and since the cation is not incorporated into the crystal, the size has little if any effect. Most of the effect is in ionic strength and Van der Waal's force. They are used pretty much interchangeably and based more on cost or availability. Of course there is no such thing as NaI in the strictest sense.
Kodak film was consistent except for the caveat I noted above about the needs of different markets. I forgot to add though that the different markets also had to adhere to different laws regarding process chemistry and effluent from the manufacturing process.
Regarding color film, Kodak tolerance was far tighter than that of any other company and as such they tried to satisfy the most exacting professional. Thus, if the film was in tolerance but off by just 0.025 in color or even less, they put in a stuffer sheet to alert the discriminating professional. Fuji and Agfa did not do this.
And, BTW, this information is in the Kodak publication "Professional Color Films" in several editions. Those interested can certainly read up on this. The film was good but to the particular professionals they tried to make it even more perfect with exact instructions.
When Fuji E6 first came out, it was so variable that Fuji was forced to withdraw it from the market until they could correct the problem. To this day, a leftover of this is the fact that Fuji suggests a different time for the First Developer of their E6 films.
1. PE do you know anything about problems regarding Kodak B/W emulsions during the first Iraq War 1991. I recently met a photographer/photojournalist who moved to Ilford and Fuji from Kodak and claimed that it was because of emulsion problems and that european photographers received subpar films because of Kodak's military contracts this was not the first photojournalist I've met who told me this story. I don't really believe that it's true but after hearing it more than once I've wanted to check if there was some truth to it.
2. I honestly doubt that Agfa was any less diligent than Kodak regarding Q.C.(also a military contractor, leading manufacturer of medical films etc...) furthermore many photographers I know favoured Agfa film because it had the best color fidelity (natural colors) and consistency. Agfapan was also know for it's superior tonal (not color) reproduction especially in the midtones.
Kodak films are superb and I love using them but they weren't that superior to other manufacturers.
Regarding my previous post I just wanted to say that it is not meant to inflame or to put doubt on Kodak's high quality and Q.C. which is above reproach.
Regarding Natrium vs Potassium PE already said it they are pretty much interchangeable. Agfa and other german manufacturers prefered potassium because they were usually part of a chemical giant (IG Farben and later Bayer Leverkusen) or companies (Perutz, Dr. Schleussner) and potassium was readily available and often a byproduct of other chemical manufacturing processes. The old german name for potassium is potasche or pot ash it's history is rather bloody literally (burned animal bones) just like the old german name Potassium hexacyanoferrate is Blutlaugensalz or Bloodlyesalt (made from mostly oxblood). The old chemical names are often very interesting and tell the history of the product.
Well, German literature lists Potassium as Kalium and Iodide is spelled with a J and thus KI is KJ in German formulas. This caused quite a "discussion" here on APUG a few years ago when one person insisted that Agfa did not use Potassium Iodide simply because he thought KJ was a "secret ingredient". But yes, I mentioned that the European film industry preferred to use Potassium salts in emulsion making.
As for Keeping or quality, I don't know of any segregation of product or orders. I do know that the military used coolers or freezers for keeping film in the tropical climate of areas near the equator. Photojournalists had no such luxury AFAIK. I heard no complaints at that time, and believe me that a widespread complaint such as this would have made news in every magazine and in every newspaper in this area.
As for Agfa films, I have used a lot of them and have run comparative tests since the '60s up until rather recently (Agfa 1000 color neg), and I found them to be quite inferior to Fuji in color and raw stock keeping. I could not even keep the 1000 speed film stable in a freezer for much longer than the actual expiration date. The earlier films were much better than the later films IMHO.
This thread is rather skewed by the fact that some companies tailored emulsions for specific markets.
Kodachrome was far more dominant in the US than the rest of the world mainly because it could be processed relatively locally so was a practical fast option, for a fast turn-around it was useless in the rest of the world as it had to go to one of a few Kodak labs outside the US by post for processing. Towards the end Kodak tried Pro drop off points offering fast service but it was far too late.
So in the UK Kodachrome wasn't an option when a fast turnaround was needed, but Fujichrome 50D or 100D (and the E4 films before that) were. I worked alongside one of the top industrial/commercial photographers on the UK (actually I was his landlord and our darkrooms were in the same building) and I saw how consistent his Fuji results were and his frustration with Kodak Ektachrome films and that mirrored my own experiences. It was why Fuji gained such a strong position in the European market.
In the US Fuji launched an E6 film that bombed aimed at the US market we never saw it in Europe, but then Kodak made products in Europe never seen in the US. However Fuji quicly broke into a US market that had been virtually 100% Kodak's, Ansco was never a threat, and they did that on price and Quality. Kodak were so complacent they let Fuji sponsor the Olympics.
What's more important is we still have good high quality film & paper manufacturers around, it's also important that former & current employees don't use APUG as a sounding board to over-hype themselves and the companies they are or were associated with.
Kodachrome film turn around was less than a week in Asian in the '50s and '60s. In fact, Fuji and Konica made Kodachrome work alike films and ran work alike processes all over SE Asia. And they sold products as far south as AU. The problem was NOT processing, it was rather the cost of the film and the cost of the processing.
Fuji charged $10 / roll for Kodachrome processing and also $10 / roll for the film. In some countries the processing was included in the price which was higher in those cases.
The dominant films in Asia were not E4 or E3. Outside of Kodachrome or Kodachrome type films, reversal films were virtually unknown. But every store sold negative films and made prints for you in 24 hours. They also sold processing kits and the formulas were published. Fuji, Konica and Oriental all used the same (old Agfa) process and produced unmasked color negatives which used a wash after the developer to aid in bringing up interimage effects. I have many rolls of that old film in my portfolio as well as the prints to go with them.
There is no mistake, B&W films and color films were ubiquitous virtually to the present day, and virtually from every company around the world. Oriental was quite big in the far east and SEA. Far larger than we might imagine. I have a 16x20 color print of a Japanese wedding given me by the head of Oriental. It is proudly displayed in my office. It was made on their new paper made to match Ektaprint 3 and Ektacolor 30 paper.
I agree the price is what killed Kodachrome and similar processes. In the last years of it's existence Kodachrome was sold in Austria for 14€ (cheap) to 22€ (more common and mega expensive) similar prices in Germany, furthermore the processing took nearly two weeks because they closed their EU processing and the film had to be send to the US. The old Agfa process was certainly not great but it was the first modern color process and the Germans and Japanese had close ties (unfortunately not for a greater good) so it's no wonder that the japanese choose to use this process. Also matching a look to a certain product had often little to do with lack of reseach but with what the costumer wanted.