I used 10-count PC for this project, which is a different animal from the bigger 7-count stuff you usually see at your local craft store. (In the photo above, it’s the stuff in the center. The “count” refers to the number of squares per inch, by the way.) 10-count has a finer finish, which takes very nicely to six-strand or pearl cotton embroidery floss.
If you can’t find 10-count canvas locally, you can get it online. It’s great stuff! (If you’re curious, the canvas on the right is 14-count. I’ve made little gift boxes with it.)