The Magic of Ink: How Pens Write

I was in the middle of taking an order last night when my pen ran out of ink.
I scribbled and scrabbled but for the life of me, I couldn't get the rest of "medium rare" written.
It made me wonder...how does ink even come out of pens?
So here we are.

It’s funny how a happy little inconvenience (like a pen running dry) can coax you into asking some truly fascinating questions.
How does that tiny ballpoint deliver its ink?
How do gel pens glide with such effortless smoothness?
Are there pens that can insert more ink into them?
What sorcery makes sure those inks flow reliably, right up to the very last drop?

I wanted to know what’s really sloshing around in there, so let’s crack it open.

The Fluid Inside

I cracked open a pen last night (in my head, at least) and expected…ink.
You know, liquid blue. Sloshing around inside.

But no. It’s way more than that. This tiny little tube is a whole mess of chemistry. Wild, in a weirdly poetic way. Let me tell you.

Dyes are sneaky things though.
Some inks, let’s call them dye-based, behave like sugar in tea.

Sugar disappears, right? Magic trick. The molecules vanish into the liquid, tinting it with color you can’t quite grab.

That’s what dyes do. They melt in, vanish, and leave a ghost of color that lingers, light, almost shimmering.
Nothing really solid.
Just…color.

Then there are the pigment types. Think cocoa powder in milk, not like sugar.
More like gritty, floating specks that never go away.

You feel them. They cling. They give that ink that richness. That density. Sometimes they can even make it waterproof, like they’ve decided to become a stage 5 clinger like me. Not going anywhere.

Here’s where the other parts get interesting:

Surfactants are the peacekeepers. They smooth the ink so it doesn't bead up. Cue Smooth Criminal music.

Humectants are the lifeguards, keeping it from drying out and turning into crusty old nothing.

Buffers are the balance guardians (like the Libras). They keep the chemistry from tipping over into chaos.

Preservatives are the microscopic bodyguards. Fighting off the mold that wants a piece of the action.

So, is that just ink?
Not even close. It's an ecosystem. A tiny, wild universe.

Every scribble? Tiny chaos. Molecules moving, ink smearing, paper drinking it up.
It shouldn’t work this well, but it does.

In ballpoints and rollerballs, water or alcohol (often isopropyl, not the kind you can drink) dominates the formula. In fountain pens, you'll find water with glycerin or glycol. Gel pens?
It’s a mostly water-based concoction with thicker agents to produce that creamy, smooth ride.

The Mechanics

At the tip of a ballpoint pen lives a tiny metal sphere (I’m sure you’ve seen it).
Brass, steel, tungsten carbide…take your pick. It’s small enough you could lose ten of them in a grain of rice.

And here’s the trick: that ball rolls. Every time you drag the pen across paper, the ball spins in its socket.
One side dips into the ink reservoir behind it. The other side presses against the page. Ink gets picked up, carried over, and rolled down in an ever so smooth little handoff.

It’s teamwork. Gravity pulls, surface tension clings, capillary action does its quiet thing in the background.
Adhesion, cohesion, all those invisible physics forces working like stagehands to keep the show going.
Fancy physics.

But, it isn’t foolproof! Ballpoints use thick, paste-like ink.
These are great for lasting months in your pocket, but not so great for flow. It dries fast and clumps.
And when the cartridge is almost empty, or when the ink crusts at the tip, the whole system sputters.

That’s when you scribble circles in the margin, begging it to come back.
Sometimes it does.
Sometimes the silence is final.

Rollerballs and gels look a lot like ballpoints on the outside! Same little sphere at the tip, with the same rolling action.
But the ink? That’s where things shift.

Rollerball ink is looser and a lot thinner. It flows like water compared to the sticky paste of a ballpoint.
Smooth as silk. Darker lines, richer color.

Gel pens take it even further. Their ink is thick, but not paste-thick. Think pudding instead of honey. It glides, it shines, it can even sparkle if you’ve got one of those glittery packs from the 90s (I wish I still had some of those!).

The tradeoff? You burn through them faster. Rollerball and gel inks don’t ration themselves the way ballpoints do. They gush. They flow. They give you beauty, but they don’t promise to stick around for the long haul.

It’s the difference between sipping slowly at a cup of tea…and chugging down a milkshake.
Both satisfying, but one lasts a lot longer.

And then there is the absolutely iconic fountain pen. Inside is a reservoir of true liquid ink. Not paste, not gel. Real liquid. Like a tiny bottle of old-world dye hidden in the barrel.

The nib (usually gold or steel) splits into a delicate slit. Ink seeps down, pulled by nothing more than gravity and capillary action. No pumping, no pushing.

It’s deliberate and incredibly dramatic. A fountain pen glides, it doesn’t scratch.
Each letter swells and thins with the tilt of your hand, the pressure of your fingers.

They’re gorgeous, but moody. Like a cat that only purrs when it feels like it.
Treat it wrong, it leaks. Hold it too long without use, it dries.
Yet when it behaves, when the feed is tuned and the nib kisses paper just right…there’s nothing else like it.

A fountain pen doesn’t just write the words, it performs them dramatically.

Why Some Work Better Than Others

Viscosity & Flow: Thicker (ballpoint) ink resists drying, but sacrifices smoothness. Thinner (rollerball/gel) offers glide, but empties quicker.

Tip Geometry: A fine point = precision, less flow. A bold nib = more flow, broader lines.

Environmental Sensitivity: Heat, cold, humidity…all can alter ink behavior.

Paper Texture: Rough tooth gives more drag, smooth stock lets ink glide.

Aging & Evaporation: Over time, solvents evaporate, thickening the ink or leaving it crusted in the tip.

The Story Behind the Ink

It started with feathers: quills plucked from birds, hollowed out, sharpened to a fragile point.
Scribes dipped them again and again into pots of ink.
Write a line, dip. Write another, dip.
Endless interruptions, blotches, smudges.
But for centuries, that was the tool. The quill was the magical bridge between thought and parchment.
These are the iconic tools I always imagine when I think of old pens.

Then came metal nibs for a much sturdier evolution. No more fragile feathers (sad). They scratched across paper with vigor, still needing their dips, but lasting a while longer, and holding shape better.

By the 19th century, inventors had a revelation: what if the ink traveled with the pen?
Enter the fountain pen: tiny reservoirs tucked inside, feeding liquid ink through capillary magic. Oh so elegant. Sophisticated, yet moody.
Too much ink and it bled across the page.
Too little and it sulked, refusing to flow.

The 20th century gave us something new: the ballpoint.
A tiny metal bead, rolling, rationing out thick ink.
Cheap to make, and nice and sturdy to carry. Suddenly the world could scrawl without blotting or fuss.

And then: rollerballs. The mid-century smooth talkers (cue music).
Same ball at the tip, but with thinner, looser ink. Darker, richer lines, with the effortless glide of an ice skater.

The 1980s and ’90s?
Gel pens stole the show. Neon pinks, shimmering metallics, glitter trapped in goo.
Every middle schooler’s notebook became an art gallery. Artists still swear by them for their vibrancy and glide.

People wanted contracts that wouldn’t wash away in the rain…hence waterproof ink. Now it’s refillable cartridges because, you know, we’d also like the planet not to die.
Biodegradable inks, refillable cartridges, a rebellion against disposables.
The pen, once a throwaway, slowly finding its way back to something sustainable.

From feathers to fountains to fluorescents, the journey has never really been about convenience.
It’s about our hunger to leave a mark.

Quick Fire Rescue Tips

Shake it gently, tip downward.
Warm with your breath or pocket, ink flows smoother when warm.
Scribble on scrap…sometimes it just gets going again.
Dip in water (for fountain pens) to loosen dry ink. Sometimes I lick mine (not recommended).
Refill or swap cartridges…sometimes there’s just no rescuing.

The Big Picture

Sure, there are mechanics.
Tiny balls rolling, ink reservoirs, chemistry doing its thing, but that’s not the part that gets me.

The charm of ink is that it’s never just science…it’s mess.
It’s a smear on your hand, a blot in the margin.
It’s halfway between chemistry and poetry, one foot in the lab, one foot in the mind.

That drop of ink?
It’s actually alive.
A little rebellion against the clean white silence of screens.

And when it runs dry…mid-sentence, mid-order…we notice.
We pause. For a moment, we wonder how this tiny, everyday thing works at all.
Then, almost without thinking, we reach for another pen, and we keep writing (because those orders won’t take themselves).

My Gel Pens and my Glitter Pens.

Sources:

“Ballpoint Pen.” Encyclopaedia Britannica, 12 Sept. 2024, www.britannica.com/technology/ballpoint-pen.

Derbyshire, David. “The History of Ink: From Ancient Egypt to Today.” The Guardian, 7 July 2012, www.theguardian.com/science/2012/jul/07/history-of-ink.

“Fountain Pen.” Encyclopaedia Britannica, 5 May 2023, www.britannica.com/technology/fountain-pen.

Morris, Peter. The Chemistry of Inks. Royal Society of Chemistry, 2009.

Petroski, Henry. The Pencil: A History of Design and Circumstance. Knopf, 1990.

Snyder, Jane. “Writing Instruments through the Ages: Quills, Pens, and Beyond.” Smithsonian Magazine, 14 Mar. 2021, https://www.smithsonianmag.com/history/history-of-writing-instruments-180977567/.

“Types of Pen Ink: Ballpoint, Rollerball, Gel, and Fountain.” The Writing Equipment Society Journal, vol. 45, no. 2, 2019, pp. 112–124.