Here is an example sketch, followed by the watercolor final:
In a recent attempt to solve this problem, I tried scanning the sketch and coloring the image digitally. I was happy with the result, but while this works for a logo, I was itching to spend more time with traditional paints.
Thankfully, I was lucky enough to see a demonstration by a local artist, Paul Mordetsky, with a newish product called Liquid Pencil. This graphite/watercolor hybrid works like a watercolor paint, but is easy to correct and lighten, even erase when dry! Here is the product description from the Blick website:
Now that I am getting comfortable with this medium, I am using it to create the sketches for my current book project, RENATO AND THE LION (Viking Children's Books, 2017). I'm able to cover larger areas of the paper faster, and drop in values more easily than hatching the heck out of everything. I can't show that work right now, but I can show these quick sketches I did when I got my first jar of the stuff:
Have you ever been sketching and wanted to cover a large area quickly? Or wanted to variegate the tone very subtly, similar to using watercolors? Derivan Liquid pencil is capable of all these things and more.
An innovative new product that allows artists to create authentic graphite pencil effects with a liquid, Derivan Liquid Pencil can be easily thinned with water to allow for the softest colors to be applied with a brush, nib, or other art tools.
Because of its precisely balanced formulation, the Permanent formula "burnishes up" like traditional graphite but won’t smudge. The Rewettable formula allows for removal with water or an eraser, similar to watercolor techniques. Large areas also can be covered quickly and easily.
Derivan Liquid Pencil is available in six graphite shades. Each shade has a definite graphite color; however, there are distinct undertones such as Blue, Yellow, Red, Sepia, and neutral Grey in two different strengths to allow artists a great range of options.
These aren't the best or most finished sketches, but I whipped them out so quickly with a relatively good spectrum of values. I also can focus on my line weights, and erase if I make a mistake. This is informative before painting with watercolors. Prior to this, pencil didn't help me figure out the calligraphic quality to the line that I was looking for. I still love the energy of my pencil sketches, and will continue to do them. But for work where watercolor or oil is the planned final art, Liquid Pencil is my new best friend.