---
title: "What is a Ballpoint pen made of?"
description: "A tungsten carbide ball a millimetre across, rolling in a brass socket, fed by thick oil-based ink. Every component, the material it uses, and the constraint that ma"
url: https://atoneplace.net/made-of/ballpoint-pen/
site: "At One Place"
---

# What is a Ballpoint pen made of?

**What is a Ballpoint pen made of?: A tungsten carbide ball a millimetre across, rolling in a brass socket, fed by thick oil-based ink.**

Ballpoints failed for fifty years before they worked, because the ink was the hard part rather than the ball. Fountain-pen ink is far too runny for a rolling ball and floods the paper; László Bíró, working with his chemist brother György in the 1930s, borrowed the fast-drying, high-viscosity thinking of newspaper printing ink instead. The consequence is that ballpoint ink dries by absorbing into the paper and by the solvent evaporating, not by soaking like a fountain pen, so it smears far less and works on receipts and cardboard where a fountain pen feathers. Gel pens went the other way — water-based pigment ink held in a gel that thins under shear — which is why they write more smoothly and run out much faster.

## Component by component

*Every material is a choice, and the third column is the constraint that drove it.*

| Part | Material | Why that material |
| --- | --- | --- |
| ball | tungsten carbide, typically 0.5-1.0 mm across | It has to stay perfectly round after kilometres of rolling under load; steel wears out of round and the line goes scratchy. |
| socket | brass or nickel silver, swaged around the ball | The gap must hold the ball to a few microns — loose and it leaks, tight and it seizes — and these alloys machine to that tolerance. |
| ink | dye or pigment in a viscous base of benzyl alcohol, phenoxyethanol and oleic acid, thickened with resin | The ink must be thick enough not to run out under gravity but thin enough to be dragged out by a rolling ball. |
| reservoir | polypropylene or brass tube, open at the back | The open end lets atmospheric pressure push the ink forward, which is also why a ballpoint struggles upside down or at altitude. |
| barrel | polystyrene or polypropylene, often with a tungsten carbide-tipped brass nose | Cheap injection moulding is the whole point: the pen has to cost less than the ink inside it. |

## Other stationery and paper objects

- [Pencil](https://atoneplace.net/made-of/pencil/) — Graphite mixed with clay and fired, glued inside two grooved halves of softwood. No lead, ever.
- [Paper](https://atoneplace.net/made-of/paper/) — Cellulose fibres from wood pulp, plus up to a third mineral filler, sizing and brightener.
- [Glitter](https://atoneplace.net/made-of/glitter/) — Aluminium-coated polyester film, colour-coated and chopped into fragments — by definition a microplastic.
- [Crayon](https://atoneplace.net/made-of/crayon/) — Paraffin wax with pigment stirred in, poured hot into a mould and cooled. Almost nothing else.
- [Cardboard](https://atoneplace.net/made-of/cardboard/) — Two flat kraft paper liners glued either side of a fluted paper medium — the flutes do all the work.
- [Eraser](https://atoneplace.net/made-of/eraser/) — Either natural rubber with fine abrasive and oil, or plasticised PVC — two different ways of lifting graphite.
- [Blackboard chalk](https://atoneplace.net/made-of/chalk/) — Mostly calcium sulfate — plaster of Paris — rather than the calcium carbonate the name suggests.
- [Playing card](https://atoneplace.net/made-of/playing-card/) — Two sheets of paper laminated around a black glue core, then coated in plastic — or solid PVC.
- [Postage stamp](https://atoneplace.net/made-of/postage-stamp/) — Coated paper with phosphor bands, printed in security inks, on either water-activated gum or a self-adhesive.

## Common questions

### What is a Ballpoint pen made of?

A tungsten carbide ball a millimetre across, rolling in a brass socket, fed by thick oil-based ink.

### What is the ball of a Ballpoint pen made of?

Tungsten carbide, typically 0.5-1.0 mm across. It has to stay perfectly round after kilometres of rolling under load; steel wears out of round and the line goes scratchy.

### What is the socket of a Ballpoint pen made of?

Brass or nickel silver, swaged around the ball. The gap must hold the ball to a few microns — loose and it leaks, tight and it seizes — and these alloys machine to that tolerance.

## Related pages

- [Pencil](https://atoneplace.net/made-of/pencil/)
- [Paper](https://atoneplace.net/made-of/paper/)
- [Glitter](https://atoneplace.net/made-of/glitter/)
- [Crayon](https://atoneplace.net/made-of/crayon/)
- [Cardboard](https://atoneplace.net/made-of/cardboard/)
- [Eraser](https://atoneplace.net/made-of/eraser/)
- [Blackboard chalk](https://atoneplace.net/made-of/chalk/)
- [Playing card](https://atoneplace.net/made-of/playing-card/)
- [Tennis ball](https://atoneplace.net/made-of/tennis-ball/)
- [Banknote](https://atoneplace.net/made-of/banknote/)
- [Golf ball](https://atoneplace.net/made-of/golf-ball/)
- [Glass](https://atoneplace.net/made-of/glass/)
- [Soccer ball](https://atoneplace.net/made-of/soccer-ball/)
- [Marshmallow](https://atoneplace.net/made-of/marshmallow/)

## Sources

- Typical range compiled from manufacturer specifications — At One Place (/about/)