Why is My Fountain Pen Leaking?

Nov 27

A leaking fountain pen can slowly become a blotchy, stained mess. To make matters more complicated, your leak could be caused by one of several factors, which means fixing the leak will require time spent investigating and troubleshooting. To help speed your leak recovery if this ever happens to you, here is a list of the most common causes of fountain pen leaks.


Barrel Cracks
Possibly the easiest place to start when visually searching for the cause of a leaking fountain pen is by checking the exterior barrel. If your pen barrel has a crack or split, depending on the internal make-up of your pen, you could find your ink leaking right out and onto your hand.

Broken Sac
If your fountain pen uses an interior ink sac, it may be the cause of the leak. Check to see if the interior ink sac is broken, or has a tear.

Worn Out Wet Seal
If your fountain pen uses a wet seal at the back end of the pen, know that over time that seal can wear thin. As a result, ink can slowly start to leak out through the seal. If a broken wet seal is the reason for your leak, your pen will need a professional repair.

Feed Issues
A fountain pen leak may be caused by a broken, misaligned, or loose-fitting feed. If the nib and feed assembly screw into the front end of the pen, try unscrewing the pen, wiping down the threads, and then re-screwing it back together to ensure the connection is tight and secure.

Air Leaks
A leak, or even excessive ink flow, may be caused by an air leak. Air leaks can occur when the opening of an ink cartridge or ink converter is not properly, tightly sealed against the pen nib. Try simply taking the fountain pen apart, and reattaching the converter or the cartridge with a tight seal to fix the leak issue.


When your fountain pen gets too warm, either from sitting inside your pocket and close to your body, or from sitting in a warm atmosphere, you’re at risk for the ink leaking out through the nib. Heat inside the fountain pen can results in expanded air, which pushes ink out through the nib.

Airplane Leakage
Be careful traveling with your fountain pen, as unpredictable leaks can be caused during air travel. This is caused by the change in air pressure that occurs inside the airplane cabin at high altitudes. When the air pressure changes, ink may push out through the nib resulting in a leak that can be difficult to manage. To learn more about how to protect your fountain pen during air travel, read our earlier blog post, “How to Safely Travel with Your Fountain Pen.”

A Note About Pens that Leak into the Cap

If you uncap your fountain pen to find the cap is lined or even puddled with ink, start your leak investigation with the nib. You may need to work with a professional to have the feed adjusted to slow the overall ink flow to mitigate leakage.

Before you take your fountain pen in for repair, however, be sure to investigate if your pen is truly leaking. If you have not properly capped your fountain pen, you may have caused some ink to leak into the cap and dry out. Dried ink can easily re-liquefy itself when mixed with air vapor that is trapped inside the pen cap. This phenomenon of dried ink inside a pen cap turning to messy liquid is one of the most common reasons fountain pen users initially think their pen is leaking, when fortunately, it’s just a false alarm.

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