I used watercolor markers for inks in the first book, then switched to a very labor intensive process using ultra fine sharpie markers in the second book.  I'm refining that process for the third book, and have begun experimenting with a middle tone grey again using some ebony pencils to play with the spaces in the drawings. 

To test out my ideas, I've been doing some scaled down, quick ink studies on the side using some of the actual layouts from the book.  With a lot of work on the immediate horizon, it's nice to iron out a few wrinkles before jumping right in. 

I'm still hoping for a late summer release...