Ink line with watercolour wash is a common medium in illustration. In the case of a picture book it can be a little daunting to ink 30 pages of illustrations, especially if you're intimidated by India ink's permanence and potential for accidents. One way to overcome this is to scan your final pencil drawing, open it in photoshop and use the levels function to darken your line. You can print the darkened and cleaned-up drawing directly onto 90 lb watercolour paper. Some printers, particularly HP, allow you to choose the paper you're printing onto. 140 lb paper is too heavy, but for 90 lb watercolour paper, choose control/command P > print > layout > paper type/quality > plain paper > greeting card > HP textured greeting card paper. If your paper has a fine deckle edge, position the paper to feed deckle first. You can then paint directly onto this "ink" illustration. You will get some bleed of the black line, but I've found it isn't too bad and a small price to pay when I have 30 pages to ink. the following is a pictorial demo of how to clean up and darken a pencil line so that it looks like an inked line. The demo concludes with the final watercolour for the cover of I Want to Go to the Moon by Tom Saunders (Simply Read, 2010) . The black line was printed on 90 lb cold press Winsor Newton paper using my HP 1220 injet printer. (And don't forget, if you're looking for a classic sepia ink look, it is easy to adjust the colour of the line using Command/control B for colour balance and Control/command U for saturation and light/dark adjustment before printing.) The drawing used for the final art is a more developed version than the one I used for the first part of the demo. I used the blueline technique to arrive at the final drawing. Click on the link for the blueline tutorial.