There is one mistake in this article, which is all too common with younger photography hobbyists, especially from the US. It is using CineStill home kits as some kind of reference for C-41. In reality, this is a cheap-o copy of Tetenal´s press kit from the 1980´s, It is not operating at the standard temperature, nor is the time standard. No photofinishers are developing C-41 at 39°C (102°F) or for 3:30 minutes, as the standard is 37.8°C (100°F) for 3:15.
Hey Samu, I presume you’ve read this, thinking of me as a younger person. I’m at the age where this feels flattering — so thanks for that!
That said, C-41 is a standardized process. It’s meant to produce identical results, although temperatures and development times can indeed vary.
If you have evidence of these kits differing in some meaningful way from what you consider a standard, I’d love to publish your findings — or you can post them right here in the comments.
Samu Skogström
Dmitri