Fountain Pen Design

Function, Development, Construction and Fabrication

057-1 The Cap – History-Overview

A Bit of History

Photo 1 — Early Quill Holder

To understand history one needs to start reminiscing before the event. Understanding the cap, I start with a historical view as shown in Photo 1 depicting a quill holder. Its function is only to store the quills and to keep the inky bits away so that they would not soil the scene.

Photo 2 — Italian Desk 1685

Photo 2 is a cropped painting with the title “Still Life with writing implements” painted by Cristoforo Munari around 1685. In the left corner, one can see a tin with a perforated lid and two quills standing in it. One could assume that there is some soft material in the container preventing the tip from damage.

In the right dark bottom corner, a sand shaker (for drying the ink on the paper) is lying on its side and in the front of the photo: a pen knife (for shaping the tip of the quill). Is it from this application where the “pen knife” received its name? (A native English speaker friend told me, it is.) Right to the penknife, the red stick in the foreground looks like seal wax and on the left of the knife is the stamp of the seal.

It appears that at the time, protection of the nib-tip and the drying of ink was of no concern. I wonder, did they ever make caps for dip-nib holders providing these functions? Seems pretty obvious.

Photo 3 — Cap for Dip Nib

And here I found one, needless to say: “On the internet”. Photo 3 shows the outer protection part and an inner cap for the reduction of the dry out. It comes with the Tachikawa Comic Pen Nib Holder Model 40. I am almost certain that there have been pre-runners of this design idea.

Photo 4

The fountain pen holder in Photo 4 demonstrates the next step of evolution towards the cap. Over and above the function of storing the pen it also offers the protection of the nib. From the picture, I cannot tell whether it also reduced dry out but with the pen resting in the nib downward position in a somewhat sealed tube, it surely would take longer.


Today the cap is an essential, integral part of a fountain pen. Its functions are to protect the nib and feed from damage and to prevent the ink from bleeding out into any wettable material the nib touches. Some caps incorporate a component, the inner cap, which seals the nib and thus slows down evaporation and the drying of the ink on the nib, which helps to maintain the pen’s readiness for writing.

For a uniform appearance, the cap is often made from the same material as the barrel. Most often the cap can be stuck onto the end of the barrel, which elongates the pen, known as posting. Some writers prefer this arrangement for reasons of balance and comfort.

The Components of a Cap

Photo 5 — Components of a Cap

If there is anything typical about caps, I have chosen the one in Photo 5 because it has all the components.  I have named the parts for consistency in this article. It is a transparent cap of a Pelikan fountain pen, obviously.

There is the main part, the body of the cap (1), showing the inner thread (2).

The metal enforcement ring (3) at the lower end absorbs any radial forces caused by misalignment when joining cap and pen. Most screw-on caps have such a metal ring often adorned with the company logo to absorb the widening forces caused by the thread, which can be high enough to crack a cap made from plastic.  In this example, the metal ring does not help because the thread is further in, away from the ring.

You can notice a thicker section (4) at the upper end for strengthening (and tool design) and several veins, which engage with the longitudinal grooves on the inner cap (5) which prevents them from rotating relative to each other during assembly and when screwing on the cap.

Note, the inner cap is blunt at its open end, more about that later. The finial with the logo (6) comes off. I guess the photographer placed it at this central position to give it importance.

The metal ring, called the clip screw (7) on the right engages with the thread on the inner cap and secures it and the clip (8) to the cap body (1).

Photo 6 — Inner Cap with Leaf Spring

Slide-on or clip-on caps often include a spring of some shape, which holds the cap to the grip section. See Photo 6.

This type of design may give some ease of operation to some fountain pen users but for the task it performs it is quite elaborate (complicated) when compared with the simplicity of the inner cap in Photo 5.

I will discuss this style at length in a separate page on the Inner Cap.


After this brief journey into history and general introduction let’s look at the ingeneering design aspects.  They are subdivided under several headings:

Cap Mechanics and Physics
The inner Cap
The Clip
• The well-designed Cap … have to think about that a bit longer

Above all: Enjoy!


Amadeus W.

09 January 2019

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