How Does A Fountain Pen Work (Beginner's Guide)

How Does A Fountain Pen Work

Fountain pens are certainly things of beauty, but even those of us who’ve been using them for decades tend to have very little idea of how they work. You can find a quality fountain pen in the desks of many musicians, calligraphers, and artists, but the knowledge of their functioning seems less ubiquitous.

So how exactly how does a fountain pen work?

The simple answer is capillary action. The more complicated answer is… well, keep reading to find out.

how does a fountain pen work

We take a look into what makes modern fountain pens tick, the role that every part plays in their function, and explain exactly how capillary action affects how the ink flows from your pen.

How Fountain Pens Work

Capillary Action

Fountain pens work by only letting a small amount of ink out at a time, often referred to as a “controlled leak.” 

Capillary action is the process of a liquid flowing in small spaces without using external forces like gravity and occurs because of the inclination of water molecules to stick together. This causes surface tension in water or water-based products, including the ink of a fountain pen.

How Capillary Action Takes Place in Fountain Pens

Fountain pens keep their ink stores in the reservoir. When the pen is being used, it’s tipped to face downward with the nib touching the paper.

Gravity pulls the ink from the reservoir down until it’s filtered into the feed and collector. The ink travels through the slit of the nib and can now be considered primed for you to begin writing. 

The design of fountain pen nibs and feeds ensure that there’s proper air regulation to avoid air bubbles from forming. This prevents leaks and splatters that could occur if any air bubbles were to pop when using your pen. 

Air regulation also ensures that the ink that’s used gets replaced from the reservoir by pulling the ink towards the end of the reservoir. This keeps everything flowing which makes the nib essentially self-filling.

After being stored, the ink from the feed enters the nib which is designed to keep the capillary action in motion and help to keep air flowing.

Once the ink has reached the nib, you’re ready to write. 

What is a Fountain Pen?

Before you can understand how does a fountain pen work, you need to understand the components that make up the pens themselves.

Fountain pens have four key parts: the reservoir, the feed, the collector, and the nib.

Fountain Pen Nib

The fountain pen nib is the metal tip of the pen. It’s pointed to allow for a smoother and more precise way to commit the ink to paper.

Some nibs come as a nib collar or ‘nib and feed,’ which is the term used to describe a nib that is directly attached to the fountain pen feed.

The nib runs a small slit that brings the ink down into the tip. The slit ends at a hole at the back of the nib, which is referred to as the “breather hole.” 

The breather hole serves to regulate airflow into the pen, as well as offering a structural purpose by providing a point for the pen to decompress to prevent the nib from cracking after recurrent use.

This regulates the airflow into the pen, which intercepts the formation of potential vacuums in the reservoir of your fountain pen. 

Keeping your nib free of dirt and dried fountain pen ink is important to allow the proper flow of ink.

Nib Thickness

Fountain pen nibs come in various thicknesses, like Broad (B), Medium (M), Fine (F), and Extra Fine (EF).

The larger or thicker the nib is, the higher the rate of ink flow. Similarly, the smaller the nib is, the more slender and fine the lines will be. This lowers the amount of ink transferring to the page and is similar to writing with a standard ballpoint pen.

Types of Nibs

There are four main types of nibs that you can use on your fountain pens.

Chiseled nibs, also referred to as Broad nibs, create thick vertical and horizontal lines but have limited flexibility regardless of the pressure applied to the fountain pen when writing.

Pointed nibs have rounder tips comparable to ballpoint pens. These nibs create uniform lines and are more flexible than their broader counterparts. The amount of pressure that’s applied to a pointed nib determines the ink flow which creates thicker or thinner lines.

Italic nibs are commonly used for calligraphy (see examples of great calligraphy fountain pens) and make for attractive handwriting.

Music nibs are aptly named to reflect their use in musical notation. The major difference in these nibs is that they contain two slits and therefore create a bigger stream of ink to the page. 

fountain pen ink

Ink Reservoir

The reservoir is the tube found in your fountain pen’s handle and comes in three different variations.

A cartridge is the most common type of reservoir found in fountain pens. This is the tube that houses one specific type of ink. Cartridges usually come pre-filled, making it easier to replace when the ink has run out. You simply buy a new cartridge and replace the old one.

The drawback of ink cartridges is the limitation on the types of ink you can use in your pen.

If you prefer to refill your ink cartridge manually, as many fountain pen aficionados do, you can choose from converter reservoir or piston filling systems.

Converter reservoirs are similar to a standard ink cartridge. The difference is in the ability to refill a converter. Once the ink reservoir has run dry, you can remove and refill a converter with your preferred ink type.

Pistons are non-removable converters that come built into your fountain pen. To refill a piston-style pen, you simply move the mechanism forward and submerge the nib into your preferred bottled ink and fill it. 

By twisting the filling mechanism on the end of your pen, the ink is pulled into the reservoir. You will need to do this slowly to avoid pulling too much air into your pen. To avoid messing, wait and allow any excess to drip back into the bottle.

While piston-style pens are popular among fountain pen owners, the refilling process can be messy and could result in air bubbles being trapped in the reservoir if it’s not filled correctly. 


The feed is a long plastic tube that runs through the inside of the pen. The feed is made up of 3 thin channels that connect the nib to the ink reservoir. 

In short, the feed allows the ink to flow to the nib through a “controlled leak,” and regulates the flow of the air coming back into the pen.


At the underside of modern fountain pen nibs are a set of grooves that are set closer to the barrel. These grooves are designed to collect the ink that flows through the writing instrument and into the reservoir.

The grooves or fins also prevent too much ink from pouring out at once to avoid leaking and a tedious clean-up. 


Fountain pens are more than just a pen. They can be a keepsake, a status symbol, or a calligrapher’s best friend.

However you use your pen, it’s always important to know the mechanics behind how a fountain pen works. By doing this you can keep everything in mint condition and know exactly what type of fountain pen will best suit you and your writing needs.

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