Simply brush, sponge or spray on some distilled water and let it dry thoroughly (overnight is best). Then, resand with your final grit paper to break off the whiskers. Now when you apply the finish, ...

We use an oil-based polyurethane finish in this story, though you can also use water-based urethane finishes with great results. But the color and depth you get are no match for oil-based urethanes.