How paper is made, from tree to sheet
Almost all of papermaking is about removing water in the cheapest possible order — and the fibres bonding to each other for free once it is gone.
Pulping
Wood is reduced to individual cellulose fibres, either mechanically by grinding or chemically by cooking away the lignin that glues them together. Chemical pulp is stronger and whiter; mechanical pulp keeps more of the tree and yellows.
Bleaching and refining
Pulp is brightened if the grade needs it, then beaten so the fibres fray. Fraying matters: more exposed surface means more bonding later, which is where strength comes from.
The wire
A very dilute slurry — around 99% water — flows onto a moving mesh. Water drains and the fibres settle into a mat, aligned slightly along the direction of travel. That alignment is why paper tears more easily one way than the other.
Pressing and drying
The mat is pressed between felts and then dried over steam-heated cylinders. As the last water leaves, hydrogen bonds form between fibres — nothing is glued in, the sheet holds itself together.
Finishing
Sizing controls how much ink spreads, coating adds smoothness, and calendering presses the surface flat between rollers.
Where this comes from
Smook, Handbook for Pulp & Paper Technologists; Britannica — papermaking. Every stage above is marked with how confident we are in it, and an uncertain one says so rather than reading like the rest.
- Difficulty: industrial.
- Time: continuous process.
- Written for: curious adult — The whole process, plainly, with the reasons.
Questions
How is paper made?
Wood becomes a suspension of fibres, the fibres are drained into a mat, and the mat is pressed and dried into a sheet. The stages above set it out at the curious adult level.
Can I build this myself?
This is an industrial process rather than a home build, so it is described rather than instructed.