To be honest, i did go over the whole ground strip with a fiberglass pen, removing as much black as possible and leaving only the parts that look fine with the mask. The sole touch up seemed a bit pointless when I was doing it. Kinda like random bits of solder on top of perfectly good copper. I also came across difficulty getting the board back into the metal 'board holder thing' under the keys as it was too thick with the extra solder on the ground strip.