ink and water brush

Originally I had bought this tiny sketchbook with the intent of using it to jot down art notes to myself (you know, actual writing) but it is so portable that i couldn't resist turning it into a sort of book o' thumbnails.  I have been having much fun with it, using some chinese calligraphy ink and water brush with (as a happy accident) a neon orange stabilo for the underdrawing.

Here are a few:

I think, however i will need to fill another water brush with a more diluted mixture for my mid-tones..