Waterproof ink is usually the first requirement of anyone doing ink and watercolor sketches. The nightmare of an ink & watercolor sketcher is when you finish all the linework, start coloring and the ink starts to bleed. Happened to me before. However, if used consciously, watersoluble ink is quite interesting, an alternative if you’re looking to minimize your gear and create loose and fast sketches.
One of my favorites is the PaperMate flair pen. My friend Tom Leytham introduced me to these as a sketching tool and it was an a-ha moment; you add a waterbrush and you’ve got multiple lineweights and different shading values while keeping maximum portability. These pens are very cheap and give you variable lines, depending on the angle you draw and the pressure you use on them. When in contact with water, the ink dissolves in a cool grey tone. This is a quick lunchtime sketch I did in Center City Philadelphia:
I’m currently not a huge fan of waterbrushes, but these are perfect for small sketches on the train or when I have an extra-limited time window. I use this setup when on the move, as I did when I sketched from the ferry with a group of USK-NYC sketchers a couple years ago:
Try this out and let me know what you think.