I finally had a chance to color in my new Minnesota song bird drawings. I used old water-colors (I think originally from a coloring book...they're quite old) and colored in a print out on 110lb card stock. The card stock isn't made to be water-colored, and the paper did warp a little, but not too bad. Coloring over printed (or drawn) ink can be tricky because you can fade the ink lines if you make it too wet or brush over it too many times. However, it meant I could try again if I messed up by just printing out another copy.