Storage Tank Steps

There is a huge rail yard in my city, and with it a number of industrial type buildings and facilities. I was needing to run some tests of a film developer I was needing to switch to so I loaded up some film and went to one of them that isn't behind a fence and locked gate; unusual in this day and age. I don't know what is stored in this tank, but I suspect it might be some kind of fuel since most trains are fueled by diesel fuel. I used a Toyo 45A, 150mm Sinaron with a #61 Dark Green filter because the stains on the tank were rust. The film was Kodak T-Max 100 rated at an ASA of 50. The developer I was testing was a formulation of Pyro, which I did not continue using and ultimately switched to D-76 in a 1:1 solution.