Sharpest tracks for me were with lith film (Ilford)-- I use this for
unsharp masks for BW negatives so I always have some on hand. I do
almost all my stuff now using Avery Clear Full Sheet Labels (when I
am in a hurry) or Xerox mylar film. With the avery labels I usually
use 20 mils as the smallest trace width -- going to 10 mils I find is
chancy.
