Fixing mistakes in watercolor

Sometimes a small piece of 220-grit sandpaper can save your life... I had to move the boundary of this white area slightly out to the right in order to fix a symmetry issue, but the area was bounded by phthalo blue, which really penetrates the paper deeply and doesn't want to let go. I scrubbed gently with a damp nylon bristle brush first, which removed some but not all the blue color along the boundary, and then I scraped it lightly with an x-acto knife (after drying the area thoroughly). This removed the color, but it also frayed the paper surface in a less than attractive way. So I cut a narrow rounded triangle from a sheet of extra-fine-grit sandpaper and used that to sand down the distressed paper surface to its original smoothness. After such drastic measures, the best thing to do then is to leave this area alone going forward. Even though it looks smooth and fresh once more, this paper is tweaked and it will not stain evenly ever again! Which is fine, since it was intended to be a highlight anyway. So the take-home message is this: You can't go back to square one in watercolor, but you can make a one time "adjustment."