So I'm developing some film for a client. Two of the rolls are Delta 400 Pro, and two of them are FP5+. My developer of choice is D76, and I dilute it 1 to 1. I do all my own film that way, but my own film is almost always Tri-X. Then I consult the Massive Dev Chart. Delta 400 Pro in D76 1+1 rated at 400 says 14 minutes. FP5+, same info, says 13 minutes. So I cut a corner and developed all four rolls in the same tank for 13 1/2 minutes. The FP5+ came out fine. But both rolls of Delta 400 Pro are *really* dense. Very heavy base plus fog. I can see images, but they will probably be difficult to print.
I also developed two rolls of Delta 100 Pro and one roll of Arista 400 according to Massive Dev, and they are fine.
The film isn't mine, so I don't know its history. Any idea what's up?
Thanks in advance,