Close your tweezers and slip the point inside the crack in trhe seed and then let them open to spread the hull. If you leave it on more than just a short time, like hours, it can cripple your plant and it will probably not be semetical at all.
The things that cause it the most is 1: Planting the seed too shallow and 2: germinating it and then planting the seed with the tap root pointing stright down. The root naturaly hooks up, then down and drags the hull off. It it's pointed down it has to push the seed up and has trouble draging the hull off.