If you want a clean crisp line, you want to get some contact paper, or shelf liner, which has less adhesive and is easier to remove, (or they have masking materials in art stores) and apply it to the canvas where you want it to be covered. You can use paper and tape to protect big areas between the masking. Be tedious and get it exactly how you want it, then spray as lightly as you can and still cover. Don't even think about touching it till its dry. Have an exacto knife handy when you pull the masking material incase you need it to preserve your shape. If you wanted brighter color, you may also want to use a sharpee very carefully. The brush would work, but you would have to be really smooth, and careful. )