The Joy of Flex

By Bill Riepl

originally  issued October 1998 in
Stylophile's Online Magazin
adapted and revised for Enter-Net
by Det Baumann, February 2000

Sometimes it might seem the "holy grail" of fountain pens. One of the first things you begin hearing about when you are smitten with this odd desire to use such an "old fashioned" piece of equipment as a fountain pen is the "flex" nib. From some of the descriptions, you might begin to assume that such nibs are a vital part of any pen collection. you may begin to feel like a failure as a collector if you don't have one, or a dozen or so!

Well, rest assured, this is not the case. I know of no requirement for a flexible nib in order to define yourself as a successful collector. Flex nibs can be troublesome to use, are more prone to damage, and tend to command a premium in price on vintage pens. On the other hand, you could be missing out on a lot of fun if you don't have at least one in your stable! 

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First, some nib terms, so you won't get bogged down in technical jargon: The Tip is, as the name would imply, the tip of the nib, that portion that actually contacts the paper. Usually, there will be  a pellet of Iridium welded to the gold or steel, although on some less expensive steel nibs, this is absent. The Tines are those portions of the nib that slopes up to the tip, separated by the slit cut in the nib. The Shoulder is the widest portion of the nib. The Breather Hole is cut into the nib at the end of the slit. This is not present on all nibs, modern Watermans, for instance, do without it, but virtually all vintage nibs have this feature. The Base is the bottom of the nib.

Let's begin with a look at what makes a nib a "real" flex nib. The word real is in quotes because there is a lot of debate over flexibility in nibs, and whether or not certain nibs should be called flexible. To begin with, all nibs are flexible, to a degree. Whether made of steel, gold, or some other metal, the tines will spread apart as pressure is applied. However, a flex nib has a much greater degree of flexibility in the tines than a rigid nib.

There are a lot of factors that contribute to this flexibility. One of the first things you might note when looking at a flex nib next to a rigid nib is the length of the tines. As you can see in the picture below, the flex nib, this one from an early Boston Safety pen, has a narrower shape, with proportionally longer tines than the far more rigid Sheaffer Lifetime nib. The longer the tines are, the more flexible they will be, if all other things are equal.

Of course, all other things will likely not be equal! Another feature common to the construction of flexible nibs is their thickness. The more flexible the nib, the thinner it will be. In some cases, this will be a matter of degree, and it can be hard to tell the difference, in others, it can be quite obvious. Just try comparing the thickness of an early Sheaffer Lifetime nib to a Waterman #6! The Sheaffer is just under 1/32 of an inch thick, while the Waterman is under half that. Guess which one is flexible......

But in addition to the thickness, and the shape of the tines, there is another important, even overriding factor to consider. That is the precise alloy of the gold (or steel, but for now, we'll be comparing gold nibs, to keep this simple), as well as the way it was tempered. There seems to be a modern misconception about the difference between 14K and 18K gold, in terms of their potential for flexibility. The difference between 14K and 18K is substantial, when looked at from the standpoint of metallurgy. 14K gold is a little over one half pure gold, .585 to be exact, while 18K gold is three quarters pure, .750. On nibs manufactured in European nations, you will find the markings 585 or 750 for 14K and 18K.

When looked at from the standpoint of how the metal behaves in use, however, the difference becomes far more academic. The other metals used in these alloys are silver and copper chiefly, to the tune of 14 parts gold, 6 parts copper, 4 parts silver in 14K, and 18 parts gold,  3 parts silver, 3 parts copper in 18K. The proportions are different, and the purer 18K gold will be softer than the 14K, but not enough to make any real difference. The construction of the nib, and the way the metal is treated and tempered make the real difference. According to reprints of a 1912 Scientific American article, Waterman nibs were work hardened by having the tines flexed by hand until they had achieved the proper degree of give without becoming too soft, or weakened.
flex1.jpg (10261 bytes)
flex3.jpg (14906 bytes) In addition to this tempering process, which results in a metal that has a greater degree of elasticity, the way the cross section of the nib is shaped will also play a large part in the performance of the nib. On most flex nibs, you can see that the material is thinnest in the area through front of the shoulder, becoming a bit more thick as it approaches the tip. Modern nibs are usually constructed almost exactly the opposite, with the material becoming thinner as it approaches the tip. Most rigid nibs maintain a steady thickness throughout the length of the nib. So, now you have your flex nib. Properly shaped, long tines that are thin through the shoulder, and thicker to the tip, correctly tempered to have the right springy give to them. Now what? Well, let's find out....