I believe things happen for a reason. In the case with Ron, the picture book I'm currently illustrating, that reason fell in my favor.
Not too long ago, I complained about having to hand transfer my images to watercolor paper because my art supply store suddenly decided that 140-pound watercolor paper was too thick for their machines. I didn't want to paint on 90-pound watercolor paper. But now that I've finished the first phase of under painting, I can clearly see a difference between the machine transfered images and my freshly drawn line work. The original line work contains a certain energy, a desired randomness, lacking in the transferred images. Besides that, with this transparent technique, some of the pencil lines will show through in the final art, so the clarity of my pencil lines are preferred.
With this book, I'm experimenting with something new (for me), a modified Flemish technique. Modified, because I'm not following all the various stages, or else I'd end up painting on this book for the next year. This technique of creating a grey-scale or "grisailles" underpainting dates back as far as the 15th century.
The next step is to seal my underpainting with a coat of varnish, tinted with a warm color, such as burnt sienna. I haven't decided if I'm going to use a tint yet. I'm going for that black and white, colorized look, from the 1950s, which has a colder feel. Think: The Andy Griffith Show in Technicolor.
In the end, probably a couple weeks from now, I'll begin add transparent layers of color, and then finish it off with opaque highlights. I'm crossing my fingers.