Ockham's razor for me - photoflo and hang, nothing else, and never a water mark ever. The kids at school go through all sorts of contortions, tools, and god knows what else and get all kinds of spots. From what I can tell, and I have not done any scientific testing on this, yet it seems to hold true with the kids, is that trying to dry too fast is the main cause of water spots. I let the film sheet the water off all by it's gravity driven self, and it always dries clean. When the kids do their thing they always try to get it dry as fast as possible and they end up with spots. I don't know if it's just me or not, but the simplest method has always done the best job.
- Randy