There used to be -- until about a year or two ago -- a neat place in downtown Northampton where you could pick from a variety of "blank" unglazed white ceramic pieces (cups, mugs, plates, etc.), decorate them yourself with different colored glazes, and then have them fired. The result would be a unique personalized and useful piece of crockery.
A few years back I made several things there, including a plate with a Turtle on it (I used a photo of this on the inside front cover of one of the TMNT Volume 4 comics), and this coffee mug.
I decided to draw all four Turtles on this one mug, and used the smallest brush they had available. I had to thin the fairly thick black glaze quite a bit to get it to the point where it would act like ink instead of gloppy paint.
As I recall, because I wanted it to look clean and tidy, I didn't do any preliminary drawing with pencil, but instead went right in with the thinned glaze. Like drawing directly in ink, that kind of thing can be a little nerve-wracking, but I like the way it came out. -- PL