Kodak to End Manufacture of Acetate

[Photo_Smith]

You conclusions are wrong according to the data sheets (from the 1990's) all EFKE materials were coated on CTA to my knowledge none of the KB, R or PL variants were ever coated on PET (Estar) base.
It is possible some of the later stocks may have been near the final production run but personally I've not seen any of these possibly you have a last production run where they might have used pretty much anything they could.
In my experience the films were quite fragile 1950's technology.
The next generation will be on PET according to Mirko CHS II and CMS 20 and Silvermax is already.

Thank you for the link but I'm well aware or the two materials 300°c metling point for CTA vs 515°C for PET the mechanical strength at over 2.5x times for PET etc etc etc

 

[haempe]

Adox/Efke KB 25 was CTA possibly you mean Adox Silvermax which is on PET base as are some of the Rollei films.

Efke films were PE; Silvermax is clear acetate

 

[Photo_Smith]

Efke films were PE; Silvermax is clear acetate

Not according to my datasheets, that may have changed I was told that Silvermax was on PET but I'm VERY happy to be proved wrong 🙂

Just tried the old tear test on my 1990's Jessop (EFKE) R100 and it tears easily, so things must have changed if you are both right.

 

[haempe]

Not according to my datasheets, that may have changed I was told that Silvermax was on PET but I'm VERY happy to be proved wrong 🙂

Just tried the old tear test on my 1990's Jessop (EFKE) R100 and it tears easily, so things must have changed if you are both right.

I don't know at which time Efke switched the base, but they have done this.
And Mirko lamented in his German forum about the price of the clear acetate base for the Silvermax...

I think the details can be found on the Adox/Fotoimpex website

EDIT: link for Silvermax and link for CHS25 (sorry, German only)