The reed pen or 'qalam' is the traditional writing instrument of Islamic calligraphers. The natural reed is seasoned so that it becomes hard enough to be used as a pen. For writing, the reed would have one end cut into an angled nib. The same reed pen is usually used for a single piece of work. If the nib is recut and the width of the nib changes, it would affect the letters. One of the first lessons for a student of Islamic calligraphy to learn is to trim and create an angled nib.