Paper is a mat of plant fibres.
The raw material is thus paper pulp, produced from a variety of fibres:
- LFibrous plants such as cotton, hemp and flax
- Paper, for recycled paper
- Historically, textiles or rags
Why different types of fibres?
- Cotton, hemp, flax and rag contain very long and solid fibres. They mat better, thus making the paper very sturdy and long wearing.
- Resinous wood has longer fibres than those of deciduous trees.
- Wood fibres from deciduous trees have different structures, but are generally shorter.
Paper pulp, in the form of sheets, is mixed with water. Then, ingredients are added to the pulp to give the paper the desired qualities for its future use:
- A small amount of mineral load (chalk, calcium carbonate, etc.) is added to give the paper its opacity and to enable it to keep its shape in all circumstances
- If required, colouring agents are added to colour the pulp
- Sizing agents are incorporated into the pulp so that the paper doesn't soak up the liquids (inks or colours). Thanks to this process, the phenomenon of linting if there is any scratching will be reduced.
Did you know? At the beginning of the papermaking process, when the fibre-and-water mixture arrives on the forming table, the paper-to-be is then approximately 95% water. In the end, the water content is around 5%!
To be read :
Papermaking on a fourdrinier papermachine
Traditional papermaking: cylinder mould