I tried another long expired Orwo NP27. It doesn’t look pretty. The emulsion got tons of defects and it seems that the beginning and the end of the film behave worse compared to the middle. In general I observe that faster films age much worse compared to an ISO50-100. These film which I got with a bunch of others films on ebay expired in 1980. Oh my, the film expired 34 years ago. Isn’t that vintage?
I developed the film in Kodak HC110 diluted 1+119 for eighteen minutes with one rotation every three minutes. I don’t think the process has much impact on the outcome. The results are and remain more or less horse shit.
However, it’s fun experimenting. Enjoy the mess.