The Fountain pen will only write smoothly if both sides of the nib consistently glide across the paper during the writing process. For this reason, the writing tips of the nib must be shaped for different writing positions. There are "straight" nibs and "*oblique" nibs. Interruptions when writing with a fountain pen that has been filled and cleaned are usually an indication that the shape of the nib tip does not correspond to the way in which the fountain pen is being held. In such cases, different nib tips should be tested to find the right one.
*Oblique nibs in most cases are special order.