When using metal reels for the first time DON'T forget to practice loading them in daylight before attempting to load in a changing bag.
A couple of days ago I had 5 x 35mm films to process and did the first 4 in my 2 Paterson Universal tanks, easy. Because the tanks and reels were wet and I didn't want end my developing session I reached for a metal tank and my new Hewes reel which I have never tried before. I had a quick look at the Hewes reel and identified the orientation needed to hook up the film on the pegs at the centre of the spool.
Once in the changing bag I had a problem getting the film to hook up in the reel. I suspect I had it skewed at the point and I didn't get the same pair of film sprocket holes hooked up properly. After hanging up the film I had 4 or 5 areas on the film that obviously hadn't been touched by developer or fix. B*gger!!!. Took the film down, Loaded it CORRECTLY in daylight and refixed the film. Lost about 6 frames.
In over 40 years of developing 35mm in Paterson tanks this is the first major developing failure I have had with 35mm. The last minor problem I had many years ago was with air bells along one edge of the film. Learnt that Paterson's instruction for 290ml solution is very tight to ensure film is covered. I usually process with another 20 - 30 ml. (HC-110 at dil H is 1+63, or 5+315 = 320ml). I also learned about tapping the tank to loosen air bubbles. Hah, the first time I tapped the tank I banged it hard on the counter top and chipped the bottom of the tank. Thus my oldest tank, about 47 years old proudly wears a battle scar from that encounter with the bench.