Added Flex

Flex Basics

Adding flex is a customization that provides for added line-width variation by carefully thinning the tines so that the nib flexes slightly depending on the pressure applied by the user. This is a customization most often favored by more experienced fountain pen users, often artists or calligraphers. Using a soft or flexible nib generally requires more skill than does using a standard stiff nib.

Nib Choices For Adding Flex

In general, adding flex is more often done with 14k nibs, as many softer 18k and 21k nibs do not have the resiliency to spring back after flexing - see our article on the best nibs for flex for more information. When combined with a regrind to needlepoint, adding flex is part of John's popular Spencerian customization. But the customization for added flex can be challenging for inexperienced users to utlilize, particularly when combined with other customizations.

Stock Soft Nibs For Flex

A very few modern pens, such as the Pilot Falcon and Metal Falcon, come standard with Soft nibs that are already semi-flexible. And any Nakaya pen can be fitted with a stock Fine Soft or Soft Medium nib as well. Many experienced users choose to have John add flex to these already semi-flexible nibs to achieve the greatest amount of flexibility possible.

Best Nibs for Added Flex Customization

In general, 14k nibs are more suitable for the customization for added flex than most 18k and 21k nibs. However, there are some exceptions. In particular, some 14k nibs that are smaller in the actual size of the nib (not the tipping point) are less well-suited to the customization for added flex, while some larger sized 18k and 21k nibs are naturally springy and do have some limited potential for added flex. Also, a long slit nib is better for adding flexibility than a short slit nib. 

Some Exceptions

For instance, the Pelikan M1000 18k nib, with its very large nib size, already has some natural springiness and can be given a customization for some added flex as well. The slightly smaller M800 18k nib shares similar qualities. Conversely, the smaller 14k and 18K M600 and M400 nibs have only limited potential for added flex due to their smaller size and deep imprints, while the now-discontinued 14k M250 nib, with its simpler imprint, is somewhat more suitable.

More Choices - Nakaya And Pilot

Nakaya's Fine Soft and Medium Soft nibs are already semi-flexible and make excellent candidates for additional flex through customization, but even the standard Nakaya and Platinum 14k nibs are still well-suited to adding flex. Nakaya nibs can also be made more flexible by adding Elastic notches. Note, however, that Platinum 18k nibs, such as on the President and some 3776 series pens, are not good candidates for flex.

The Pilot Custom 912, Resin Falcon, and Metal Falcon series pens have the most flexible solid gold nibs available today and make excellent candidates for additional flex as well. In contrast, the inlaid Vanishing Point nib is unsuitable for flex.

The Custom 74 pen, despite its 14k nib, has only limited potential for flex, while the 18k Custom 823, Yukari Royale, and Emperor nibs, due to their larger size, do have some value for additional flexibility. In contrast, the larger size handcrafted ebonite pens created by Eboya of Japan utilize 14k German-made Bock nibs which are well-suited to added flex.

Sailor and Aurora

Sailor's 14k Sapporo and 1911 Mid-Size series nibs have very limited potential for added flexibility due to their smaller size, while the large 21k King of Pen has a springiness similar to the Pelikan M1000 and can be given some added flex as well. Similarly, the larger Aurora 14k nibs on pens such as the 88 and Talentum are well-suited to adding flex, while the smaller 14k nibs on pens such as Finesse and Ipsilon De Luxe are less so.

Still Have Questions?

So while larger size nibs and 14k nibs are usually the best prospects for flex, there are still plenty of exceptions based on the particulars of any given pen and nib combination. Still have questions? Just contact us by e-mail at and we'll be happy to help.