Marc said something at the workshop that just didn't sound quite right to me, so I thought I'd verify it today. He said, once you had watercolor paint on the page, if you tried to add ink it wouldn't work as the ink would 'feather' and be fuzzy. Well perhaps the ink he uses does that, or maybe it's his combination of ink and paper because I have a lot of pens that don't 'feather' when applied after the watercolor has dried. Forgive the uni-ball white gel pen, it is basically empty and so that wasn't a fair test (I've used it many times over watercolor). So word to the wise test for yourself when someone says, 'You can't do that'.