I pre-washed my Tmax 100 MF 120 for 30 seconds with water, when I dumped the wash into a bucket it was very dark/purple. I developed as normal and when the developer was added to that bucket the purple water was cleared (or was it when I added the fix?), either way there was undeveloped material in that pre-wash water. My negs were a little flat. I'm wondering if pre-wash with roll film is not required. I always prewash my 4x5 TriX 320 with great results. Is Prewash recommended with sheet or roll film? Would it have mattered, i.e. does the developer "stick" the image to the base, or can that undeveloped latent image be washed away or degraded in 30 seconds of water prewash?