Be careful of the spot putty. The stuff never stops shrinking. OK for very light scratches and such, but it will crack eventurally if used in too large an area. I use a catalzyed spot putter called glazing compound (I use soem stuff called Dolphin Glaze). Works and sands pretty much like the old spot putty, but it's catalyzed so, once it cures, that'ts it. What you have is what you have. No concerns about shrinkage.