Never been to Hendricks mill myself, I'm down in Dorset so a bit far, but shadow figures in old industrial buildings is something I've been looking into for a while now. There's something about those places - the machinery, the weight of all them hours people spent working there, maybe dying there - that seems to attract them.
What did it look like when you saw it? I always ask this because people describe them differently. Some say completely solid black, some say more like a dark mist that holds a shape. In my experience the solid ones are the ones worth paying attention to.
Anyone else here actually visited the site before demolition? Would be good to hear from people who went in person rather than just speculation. I've read too many threads that go nowhere because nobody actually has a firsthand account to share.