What is a Paper made of?
What is a Paper made of?
Cellulose fibres from wood pulp, plus up to a third mineral filler, sizing and brightener.
The most consequential thing about paper is its acidity. From the mid-nineteenth century, paper was sized with rosin set by alum, which leaves acid in the sheet that slowly hydrolyses the cellulose — which is why library books from 1880 to 1980 crumble while books from 1600 do not. The industry moved to alkaline sizing from the 1980s, partly because calcium carbonate filler cannot survive in an acid sheet and is far cheaper than fibre. Modern archival paper is buffered with calcium carbonate specifically to neutralise acid absorbed from the air, and the mark to look for is a permanence standard such as ISO 9706.
Component by component
| Part | Material | Why that material |
|---|---|---|
| fibre | cellulose from softwood or hardwood pulp, or recycled fibre | Softwood fibres are long and give strength; hardwood fibres are short and give a smooth printing surface, so most papers blend the two. |
| filler | ground calcium carbonate or kaolin clay, 10-30% by weight | Mineral is cheaper than fibre, fills the gaps between fibres for a smoother, more opaque sheet, and stops ink showing through. |
| sizing | alkyl ketene dimer or rosin | Untreated cellulose is a wick; sizing makes the surface water-resistant enough that ink sits in a line instead of feathering. |
| optical brightener | fluorescent whitening agent | It absorbs ultraviolet and re-emits blue, so the sheet looks whiter than white — which is why paper glows under a UV lamp. |
| coating (glossy paper) | clay or calcium carbonate in a latex binder, calendered | A coated surface holds ink dots on top rather than letting them spread into the fibres, which is what makes photographic printing possible. |
Other stationery and paper objects
- Pencil Graphite mixed with clay and fired, glued inside two grooved halves of softwood. No lead, ever.
- Ballpoint pen A tungsten carbide ball a millimetre across, rolling in a brass socket, fed by thick oil-based ink.
- Glitter Aluminium-coated polyester film, colour-coated and chopped into fragments — by definition a microplastic.
- Crayon Paraffin wax with pigment stirred in, poured hot into a mould and cooled. Almost nothing else.
- Cardboard Two flat kraft paper liners glued either side of a fluted paper medium — the flutes do all the work.
- Eraser Either natural rubber with fine abrasive and oil, or plasticised PVC — two different ways of lifting graphite.
- Blackboard chalk Mostly calcium sulfate — plaster of Paris — rather than the calcium carbonate the name suggests.
- Playing card Two sheets of paper laminated around a black glue core, then coated in plastic — or solid PVC.
- 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 Paper made of?
- Cellulose fibres from wood pulp, plus up to a third mineral filler, sizing and brightener.
- What is the fibre of a Paper made of?
- Cellulose from softwood or hardwood pulp, or recycled fibre. Softwood fibres are long and give strength; hardwood fibres are short and give a smooth printing surface, so most papers blend the two.
- What is the filler of a Paper made of?
- Ground calcium carbonate or kaolin clay, 10-30% by weight. Mineral is cheaper than fibre, fills the gaps between fibres for a smoother, more opaque sheet, and stops ink showing through.
Related pages
- Pencil Graphite mixed with clay and fired, glued inside two grooved halves of softwood. No lead, ever.
- Ballpoint pen A tungsten carbide ball a millimetre across, rolling in a brass socket, fed by thick oil-based ink.
- Glitter Aluminium-coated polyester film, colour-coated and chopped into fragments — by definition a microplastic.
- Crayon Paraffin wax with pigment stirred in, poured hot into a mould and cooled. Almost nothing else.
- Cardboard Two flat kraft paper liners glued either side of a fluted paper medium — the flutes do all the work.
- Eraser Either natural rubber with fine abrasive and oil, or plasticised PVC — two different ways of lifting graphite.
- Blackboard chalk Mostly calcium sulfate — plaster of Paris — rather than the calcium carbonate the name suggests.
- Playing card Two sheets of paper laminated around a black glue core, then coated in plastic — or solid PVC.
- Tennis ball Sport and games
- Banknote Around the house
- Golf ball Sport and games
- Glass Building materials
- Soccer ball Sport and games
- Marshmallow Food and drink
Sources
- Typical range compiled from manufacturer specifications — At One Place