Retouching a lot of files from scanned 35 mm negatives spanning several years, I noticed that I have a serious re-touching problem only with Delta 100 (my other standby being Tri-X). I appreciate that the emulsion on Delta 100 is very much thinner than that on Tri-X, and at first thought I supposed it was therefore likely to show up specks of dirt more. But if the dust is opaque, it will block light to the scanner whatever the thickness of the emulsion. And the thinner emulsion takes less time to dry, so it should accumulate less dust. Can there be any other complication to explain the difference? I filter all chemicals and wash water using a Paterson 20 micron filter. Washed films are dunked in wetting agent and air-dried. Before scanning, all negs are puffed with a rubber blower and gently brushed, then carefully inspected for dust. If the dust were in the scanner, it would show on all negs and presumably get worse with time. Any suggestions much appreciated, thanks.