I am not a pipemaker by trade either Anthony, but I have been a professional woodworker my entire life. We never raise the grain with water unless we will be using a water based stain and/or finish, which is rare in commercial woodworking. If you are going to raise the grain, do it when you are on your final grit. Remember to sand very, very lightly after raising the grain, just knock off the fuzz that you've raised. If you sand any more than that you are defeating the purpose by exposing fresh fibers.