I tried an alcohol ink patina on my brass Nemesis yesterday. I'm undecided on whether or not I like it. I used blue and lime green Adirondack ink on those Adirondack felt pad thingies. Two coatings makes it show up more. The only things I had to seal it with were water based varnish and Krylon. The Krylon removes the ink, so I put two light coats of the varnish on, then sprayed on a coat of Krylon.
When I did it, I put all the tubes together, and removed the two brass end caps so the tubes would all match, and the caps would both stay brass for contrast. I put the end caps back on when I sprayed the Krylon, because I figured the Krylon would help keep the end caps from tarnishing. My husband and mother thought it looked pretty. I'll try to take a picture of it today.