Recently I stained a white mahogany exterior door using MinWax oil base stain. I used only one coat because the homeowner did not want the color to be any darker. I put one coat of Helmsman Spar urethane on the door and noticed a couple of runs. I tried to sand off the runs with 220 grit sandpaper and it began to take the stain off. Any advise??? Some one told me a high grit sandpaper soaked in Mineral Spirits. Any help would be appreciated.