Tuesday, 12 March 2013

Modern Film Creases More Easily?

Until last week I had not developed a film for over 20 years. I did so for reasons that will become apparent in later posts.

I was using 35 mm Ilford FP4+ and noticed that it seemed to crease much more easily than the old FP3. I had to be very careful even when hanging it up to dry and, later, putting it into the scanner.

To make sure my memory has not been playing tricks I dug out some strips of FP3 negatives from the 1960s. Sure enough, they were much more difficult to crease. Apart from feeling more robust, they also seemed thicker. So, out came my vernier calipers to see if the overall thickness had changed (I knew emulsion thickness has been reduced over the years). I made five measurements at different places on the strip. The average for my 2013 rolls of FP4+ came out 12.8µ (I shall use the old non-SI unit µ instead of typing 0.0128 mm). That agrees nicely with the Ilford technical information of 12.5 µ as the thickness of acetate base. 1960s FP3 was 14.5 µ while a 1960s Kodak film was 13.8 µ.

So, old FP3 was thicker (by 13%) than modern FP4+. Is that difference sufficient to account for the lack of flexibility that leads to creasing — or is the base of different material? Whatever the reason, old FP3 was — and is — much easier to handle before and after development than FP4+.