The joy of flex, part one

This flourish is made with a superflex nib on an E. Johnson dip pen from the 1800s. Even then, superflex nibs were a bit of a specialty item; and their relative fragility made their survival to modern days less likely. Note how the ink separates to follow the individual tines as they spread past the ink’s ability to maintain a sheet across the gap.

"How do you know when a nib is flexible?" asked the puzzled young man before me, a frown crinkling between his eyebrows.
"Uh-h-h. . ." My response, slightly less than articulate, illustrated my bafflement. For me, it’s kind of like breathing -- hard to explain step by step to, say, a fish with new lungs. But the young man had a legitimate question: How do we determine whether a nib is rigid, semi-flex, flexible, or a wet noodle? How can a person judge whether he or she might like to try one, or for that matter what it ought to do once in his/her possession? Can we make comparisons to pens that nearly everyone would have access to, so we’ll have a more or less equal baseline for comparison?
That sent me on a quest to those more knowledgeable than I about nibs, metallurgy, calligraphy and flexible-nib-based handwriting, and flexibility in general. Sam Fiorella, John Mottishaw, Pier Gustafson, and David Nishimura, to be exact -- all well-known and well-respected names in the pen-collecting world.
First, we should note that nib flexibility involves many factors. Among those are alloy composition, tine length and width, nib thickness, slit length (to some extent), and others. Less controllable factors (at least as far as objective analysis is concerned) come into play, also, such as the writing characteristics of the person wielding the nib -- for example, the pressure on the nib and the angle at which it’s held to the paper. And if those weren’t daunting enough, we still have to add the physics involved, which includes such things as friction, opposing forces, and things I haven’t messed with for 30 years.
You can relax; we aren’t going to go into those technical bits. They can be fascinating, but also complex, and deserve detailed discussion on their own. Since they aren’t relevant to our main point, which is how to determine a nib’s flexibility and give it some sort of classification, we’re going to ignore most of them.

General classification agreement
I was pleased to see that everyone essentially agreed with my initial assessment: The only practical way to determine a nib’s flexibility is to try it out -- feel it -- and judge its behavior against that of other nibs. In other words, we all use a subjective/relative assessment rather than an objective/measurable one (although I’m sure such a set of criteria could be developed if one were so inclined).
"I judge it like you do, by the feel of the nib and just how it writes," said Fiorella. "No magical formula!"
Nishimura offers descriptions that he uses to judge flexibility:
Semi-flex: nibs with "suspension," i.e. they respond to pressure with a change in feel, but without creating significant line variation.
Flex: nibs that provide significant line variation.
Superflex (the "wet noodle" variety): nibs that must be used with a light touch, that open up with very light pressure and can be destroyed by careless or inexperienced handling.
"There’s really not much more one can do, as a practical matter," Nishimura said. "There’s no simple answer to flex descriptions."

Above left, you can see some of the typical characteristics of a rigid vintage nib: short, stubby tines and a short slit with a broader shoulder. Above right, a more flexible nib with longer, thinner tines, a narrower shoulder, and a slimmer profile overall.

Many pen experts recommend testing a nib for flexibility by pressing it gently against your fingernail. The more quickly the tines spread and the lighter the pressure, the more flexible the nib. This nib, on a 1920s Conklin, is fairly flexible, spreading significantly with little pressure.

A simple methodology
Mottishaw, the metallurgist and nib-modifier in the crowd, had similar thoughts but a different way of expressing it, and offers a simple, easy test for flexibility. "Rather than an objective criteria I would describe a methodology," he said. "Because flexibility is a characteristic in a gold nib, to bend when put under pressure, the test becomes one of feeling.
"What I like to do is place the tip of the nib on my left thumbnail and feel how much pressure is required in order to separate the tines. I suppose one could measure that in grams (ounces might be a little crude), but I never have."
Obviously, then, the lighter the pressure needed to cause the tines to spread appreciably, the more flexible the nib. The thumbnail test is a common one among penfolk; look around any pen show or gathering of pen collectors, and the fountain-pen users will be testing each other’s nibs on their thumbnails for just the effect Mottishaw mentions. (Caveat: Do this gently and cautiously until you know what you’re doing so you don’t accidentally spring a nib beyond its ability to recover.)
It’s significant, also, that people experienced with flexible nibs tend to the definitions Nishimura offered. Agreement was pretty much universal as to what constitutes rigid, semi-flex, flex, and superflex. That will make our task somewhat easier.
Gustafson, a professional calligrapher and graphic designer who creates the exquisite thick/thin flourishes of Spencerian, copperplate, and related hands with the ease with which most of us blink our eyes, once wrote and illustrated a pocket-sized booklet, which he jokes is "fraught with subjectivity," that delved into the intricacies of nib flexibility. It’s important to note at the outset that the mark of a top-notch calligrapher is not the breadth of line, but the fineness of the finest line produced and the quality of the transitions from thin to thick and vice versa (the desirable qualities vary from hand to hand). It takes considerable control to make that just-barely-there stroke (and make it consistently) preparatory to the pressured stroke that splays a nib. Part of the nib’s ability to do that is the only other nib quality we’re going to discuss, and that briefly: Return, as Gustafson calls it.
Return refers to the rapidity with which a flexed nib returns to its original shape. If it does so instantly when pressure is released, it has a fast return; if more slowly, a slower return. This will affect the kind of thin/thick lines it will make, regardless of who’s wielding it. A fast-return nib will allow an instant switch on the upstroke from thickest to thinnest line; a slow-return nib will not, and will result in a more gradual change from thick to thin. Sometimes this is desirable; sometimes not.
We’ve compiled a list of modern and vintage pens that tend to exhibit the characteristics we’re illustrating. This list is not exhaustive, nor even hard and fast. It’s entirely possible to have variation within manufacturers and within the same model range. We hope that at least one or two among them will be available to everyone, so you can try the various nibs against your own thumbnail and get a feel for flex vs. non-flex. In addition, these descriptions will help readers understand exactly what we mean in future when we classify a nib as flexible, semi-flex, or rigid.

Rigid nibs, which have little to no flex, leave lines of uniform width regardless of pressure. Left to right, Rotring Core, XS nib (about the same as F); Retro 51, M; Visconti Pericles, F; Cesare Emiliano, M. Please note--these images are intended only to illustrate line-width variation, not to be beautiful!

Rigid nibs
Most modern nibs fall into this classification. They often are just as suitable as ballpoints or rollerballs for multi-copy forms and are certainly easier for ballpoint-reared hands to master. I can’t think of a modern nib that’s genuinely flexible (Nakaya and Namiki Falcon would fall into my "soft" category). The change in fashion to rigid nibs occurred in the early 1920s when the first Sheaffer Lifetime and Parker Duofold nibs were made thick and solid to live up to their long warranties. Sheaffer Lifetimes and Senior Duofolds from 1924 through 1930 will usually be rigid, as are all Waterman’s manifold nibs, and most vintage manufacturers -- Conklin, Wahl-Eversharp, Mabie Todd -- included rigid nibs in their line-ups. The Parker 51s and Sheaffer conical (Triumphs, Snorkels) and inlaid nibs (PFMs, Imperials) generally fall into this category. Contemporary pens with rigid nibs include such readily available (and usually inexpensive) pens as the Parker Vector, Sheaffer No Nonsense, Diplomats, Heros, Cesare Emilianos, Pelikan Futures and Pelikanos, and disposable fountain pens such as Pilot Varsitys. Most modern Waterman nibs are rigid -- a nice irony, since their early nibs were among the most expressive in the industry -- as are most current Parker and Sheaffer nibs.

These lines, made with semiflex nibs, show slight variation from very light to fairly heavy pressure. Left to right, Ancora Ravenna, F; 1940 Sheaffer Balance, EF; 1940 Parker Duofold, F; modern Pelikan 400, F.

Semi-flex nibs
Most Pelikan nibs, on the 400 models and up, tend toward semi-flexibility. When pressed, these "soft" nibs give slightly, imparting a gentle, cushion-like "bounce" to the feel of the writing. This doesn’t give significant line variation, but it can set up an engaging writing rhythm; it’s almost as if they give your fingers a boost toward the next letter. Semi-flexes also can be found in many of the Italian brands, such as OMAS, Stipula, Delta, and Ancora. Nakaya's flexible nib is on the soft side of soft for me; it comes closer to old-style flex, but isn't quite. Generally, you’ll not find these among the under $100 pens (although there can be exceptions, usually where you least expect them). Waterman #2 nibs from 1915 through 1925, with the New York imprint, and Sheaffer’s ca. 1920 self-fillers are vintage examples.

With flexible nibs, we begin to see some genuine line variation (and it takes much less pressure to get it). Left to right, Security, F nib; Waterman’s #7 Red, F; 19th Century Aikin-Lambert dip pen, F-M

Flexible nibs
Among early flexy Waterman nibs, the #2s are the most ubiquitous. The flexibility of the Pink and Red nibs in the 5 and 7 series is legendary. Wahl, Conklin, and Mabie Todd made a range of flexible nibs in the semi-flex and flexible categories. Mottishaw adds that few truly flexible nibs were made after 1930 and even fewer after 1940, but points out that Canadian-made post-1930s Waterman and Parker pens slated for export often had flexible nibs, as these had a place in the hearts of many Europeans (who also had flexible Pelikans, OMAS, and Mont Blanc pens to choose from).
Pre-1920 Parker and some early Sheaffer nibs had lovely flexibility, too. Dip pen nibs usually offer more flex at lower prices, and it’s really not that difficult to learn to control the ink flow with a dip pen. I still use them to write letters from time to time and find it quite soothing. That can make it an inexpensive way to try out flexible nibs to see if you like them. I'm reminded of a craze for Sailor's Zoom nibs a while back -- everybody had to have one, but the majority of people realized after they'd bought the specialized nib that they couldn't handle it well. You won’t find any modern fountain-pen nibs that are genuinely flexible, no matter what their manufacturers and catalog-writers say.

Note the differences in ink intensity in these examples of superflex lines. The left one has a slower return than the one on the right; and you can see that when the nib is spread to its maximum, the ink lays slightly thicker toward the outside edge, near the tines. Also note the curlique outline at the end of the far-right example; as the nib was lifted, the tines sprang back together quickly enough to leave an instructive footprint. Left to right, Mabie Todd, Aikin Lambert, Fairchild, all dip pens from the late 19th and early 20th Centuries.

Superflex nibs
Waterman, Mabie Todd, and Wahl-Eversharp are about the only vintage firms that made superflex nibs, and they can be hard to find. After all, super-flexibility wasn’t something everyone wanted even when the pens were originally made. Some Parker and Conklin nibs from about 1910-1917 can fall into the superflex category, but they aren’t common. You’ll find this quality most often in dip pens from the mid 1800s onward; you won’t find it in any modern pen. Be sure, if you’re considering a superflex or even a flexible nib, that you have an opportunity to try it gently and see how quickly and widely the tines spread. A pen show is a perfect place to do so, with a vast array of nibs and a lot of people to help you choose (and test gently). If that’s not an option, members of pen-related lists and boards online are good sources of information, too, and again, some dip pens at your local art store can give you an inexpensive trial run.
The accompanying illustrations, which make no pretense as to beauty but are utilitarian only, should help you judge where on the flex spectrum a specific nib falls. Using superflex pens requires a delicate touch that does not come naturally to hands reared on ballpoints, rollerballs, and the like.
Flexible nibs part two discusses what flexible and italic nibs are supposed to do, with the goal of helping you decide whether you want one or are getting the most out of those you already have.