I used gel pens and watercolor pencils on some of the illustrations in this coloring book. The gel pens colored more richer than the watercolor pencils. If I would have added water to the watercolor pencil drawings they probably would've come out richer-looking. I didn't want to add water to this coloring book or tear out a page to add water separately, which is why I didn't test out the watercolor pencils with the drawings in this book. I have colored on some pages on the right hand side of this book because sometimes it is awkward to color on the left-hand sided drawings. One of the pages has already come out of the book (I think because I had to bend the book to make coloring on the pages easier), so it will be easier for me to color the left-sided drawing with that page.
One thing I noticed with the drawings I colored is that I used A LOT of color on them, which I think is good because I could visualize what colors to use throughout most of the pages and there was very little white left on them.
My review = 4.5 out of 5 stars
Disclosure of Material Connection: I received this book free from the publisher through the BookLook Bloggers <http://booklookbloggers.com> book review bloggers program. I was not required to write a positive review. The opinions I have expressed are my own.