Watercolor on canvas is really fun. I did this little piece recently from a photo I took while at the beach last year.
Yes, this piece is layered (poured). I treat the canvas with Golden's White Absorbent Ground, several thin coats. Then I treat it just like I would any watercolor paper. The nice thing is that I can mask and dribble paint, and I can also easily lift! This little painting is now on my etsy shop.