Difference between flexibility and smoothness?
Why does adding flex not increase smoothness?
Flexed Nibs Are Less Smooth
Adding flexibility is a customization that provides for added line-width variation depending on the pressure used while writing. However, adding flex actually makes for a less smooth writing experience, as the tines on a flexed nib move independently and are more exposed, tending to catch on the paper. This scratchiness or feedback is actually a desired feature with a flexed nib, but is in contrast to the smoothness normally valued when utilizing a fountain pen.
"Soft" Does Not Mean Smooth
Confusion can also arise because stock flex nibs, such as those on the Namiki Falcon series, are usually referred to as "Soft" nibs. "Soft" in this instance does not refer to smoothness in writing, but to the fact that the nib tines are designed to be soft and to flex while under pressure.
But Soft And Flexed Nibs Add Distinctiveness To Your Writing
So while both stock soft and custom flex nibs are great for artists, calligraphers, or just anyone looking to add more distinctiveness and variation to their writing, they are not designed to be the smoothest possible writers. For that, look to standard stiff nibs. And remember that any pen or nib unit you purchase from Classic Fountain Pens, whether stiff or soft, standard or customized, will be tested and optimized for your personal writing characteristics before it is shipped on to you.