why do pens leak

Why do pens leak?

Have you ever wondered why do pens leak? or How to stop a pen from leaking? Sometimes for no reason out of no where there is ink all over your fingers or in your pocket.

No matter what type of pen I use they all leak at some point. I have had ballpoint pens, gel pens, micron pens, quill fountain pens and brush pens all leak on me. I decided to start digging into why and see if there is any real reason to why pens will start leaking and how to prevent it.

Pens, such as felt tip, ballpoints, rollerballs, and fountain pens hold their ink in a small tube inside the pen.

It turns out that the ink viscosity & surface tension is the culprit. If the ink is warmed up enough it will become more liquid and the ink will get push out of the cartridge.

Many inks are water-based. So your own body heat can cause this to happen.  By having a pen sit in your pocket or just using a pen to write or draw can be enough to create a temperature difference that could cause a leak.

Also the cold can be equally destructive to your pens. If a pen freezes the liquid inside will expand and that can force ink out. Damaging or cracking the ink cartridge causing a bigger mess with the ink as it returns to room temperature.

Proper way to store pens

In general there are 3 ways to store pens

  1. Nib pointing up right
  2. Nib pointing down
  3. Nib pointing sideways (horizontal)

I mainly always store all pens horizontally. This helps to keep the nibs wet enough to start writing or sketching as soon as I start with out leaking.

  • Ballpoint pens I store these up right.
  • Sakura Micron pens  & Staedtler Pigment Liner horizontal and in a case.
  • Brush pens horizontal and in a case.
  • Fountain pens horizontal and in case.

Best way to carry pens

my pen case
my pen case


Carrying pens correctly will help with preventing issues with leaking. I prefer to transport / carry my pens capped and in a case. The image above is how I typically carry my pens that I draw with.

  • Keep pens capped.
  • If possible carry the pen in a case laying horizontal.
  • If you are going to carry a pen in a pocket try to keep them in a vertical orientation capped end up. That means the nib should be pointing upward.

Leak proof pens

From what I can tell and have read I don’t believe there is actually such a thing as a leak proof pen. With how ink works there is always the chance you could get a leak.

Your best bet is to buy a good quality pen and cap your pen when possible. Carry them in a way that will help prevent leaking along with trying to store them in a stable temperature – not to hot and not to cold.

My main take away and personal choice is to spend a little more money on a good pen. You will get better quality in construction and be less likely to have random leaks.

Everyone has there own preference in pens and the way they want to store there pens. It is unique and can vary for each individual. So experiment on what pens you use and how you keep them to find the right combination.

I hope this has helped shed a little light on this topic and has been helpful in some capacity. Thank you for taking the time to read through.