Why Do Pens Explode?

Have you ever stuck a pen in your pocket for safekeeping and then reach in later to find your hand covered in ink? How can such a little thing make such a big mess?

Pens explode when they are exposed to increased temperatures such as body heat or a hot external environment. The high temperatures cause the ink to liquefy and bleed out of its plastic encasement.

In this article, we will go into detail about the reasons why pens explode and what types of pens are more likely to explode than others. We will also cover what pens do not explode and how to prevent your pen from exploding.

Table of Contents

What Are the Different Reasons a Pen Can Explode?

There are a few reasons why a pen can explode including temperature changes, capillary action, and damage to the pen tip.

If you expose a pen to hot temperatures by storing it in your pocket, leaving it in the sun, or placing it next to a heater, the ink stored in the pen will turn into liquid. If the pen is stored with its tip pointed down, then the liquid ink will leak out due to gravity.

Why do pens explode?

Pen ink can also be drawn out by capillary action. If you leave a pen uncapped and place the tip against an absorbing material such as the fabric of your shirt or pants, the physics of capillary action will draw the ink out of the pen into the absorbent material.

If your pen tip becomes crushed or damaged, then the integrity of the pen is compromised. Pens are designed to have secure tips that release ink when pressure is placed on the tip by writing. If this design is tampered with or destroyed, the ink can leak out unchecked.

Are Some Types of Pens More Likely to Explode than Others?

Ballpoint pens and rollerball pens are more likely to explode than other types of pens. The way these pens are constructed encourages leakage if exposed to high temperatures such as body heat. There is a small ball at the tip of the pen that stops the ink from coming out even if the pen is shaken or dropped.

Only when pressure is put on the ball does it move to allow a controlled amount of ink to flow out. However, if the ink becomes too liquid, then the ball will not be enough to prevent it from leaking out since it is not a solid seal.

Are There Any Pens That Do Not Explode?

No pen is completely leakproof. However, there are pens that are less likely to explode. These include modern fountain pens and gel pens. Despite having a reputation for leaking in the past, fountain pens are now designed to prevent leaking and explosions. Even body temperature will not cause this pen to explode. However, use caution when flying because the increased pressure could cause a rare leakage.

Gel pens are also less likely to leak because their ink is thicker, so it takes longer to liquefy when exposed to high temperatures. However, given enough time in the heat, gel pens will explode like other pens so make sure to store them away from hot environments.

How Do I Prevent My Pen from Exploding?

There are a few simple steps you can take to prevent your pens from exploding. Always make sure that they are stored with the cap on or the tip retracted. Don’t put pens in your pockets, as your body heat may cause the ink to liquefy and leak. Keep pens stored in a cool environment away from direct sunlight or heating units.

To mitigate pen explosions and large messes, keep your pens stored with the tip upright or in a neutral position so that gravity doesn’t pull the ink down and out of the tip. Putting your pens in a drawer or in a jar is the best way to prevent pen explosions.


If you are sick of dealing with exploding pens, there is a solution. Most of the time, pens explode because the ink in the pen liquefies due to increased temperatures from exposure to high environmental heat or body heat. Other times, contact with absorbent fabric by the pen’s tip can draw ink out.

Properly store your pens away from heat sources and out of your pockets to prevent explosions. Take special caution with rollerball and ballpoint pens which are more likely to explode. Gel pens and fountain pens are less likely to give you leakage issues.

Store your pens in an upright or neutral position to prevent the ink from flowing out unchecked. Always recap or retract the tip of your pen to store it. If you follow these simple prevention methods, you won’t have to worry about pen explosions anymore.

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