Not necessarily true here! You can trap flux inside a weld and make a nasty inclusion in the finished piece. You want enough flux to coat the workpiece and give it a glassy look while hot. Provided that you prepped your steel properly, the flux is mainly a barrier to oxygen.
One other thing to note. When you're setting the weld, you don't need to hit the billet like you're Thor. A medium blow is all you need. It's more important to move the hammer blows rapidly across the workpiece and set things in place than to smash the crap out of it. If you hit it too hard you'll just cause the layers of the billet to slide sideways rather then weld.
-d
