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Paper is a thin sheet made of matted cellulose fibers. Most paper is derived from lignocellulose, which is a material found in plants. The production process involves turning this material into a liquid pulp or slurry. This slurry is then drained and dried into flat sheets.

PaperAutofluorescence
PaperAutofluorescence

Paper comes in many varieties. These types are defined by their fiber content, pulp, sizing, coating, size, density, and grammage. Understanding how paper is made helps us see how a simple plant material becomes a tool for communication.

The manufacturing process begins with creating pulp. Pulp is a mixture of isolated fibers. There are two primary ways to make this: chemical pulping and mechanical pulping. In chemical pulping, a cooking liquor is used to dissolve the lignin. Lignin is the substance that holds wood fibers together. By dissolving it, the cellulose fibers are preserved and kept long.

20221129 low quality paper
20221129 low quality paper

This produces wood-free paper, which is more durable because it lacks the lignin that causes deterioration. There are three main chemical methods: the sulfite process, the kraft process, and soda pulping. The kraft process is the most common today. It is unique because the reaction with lignin produces heat. This heat can actually be used to run a generator for electricity.

Mechanical pulping is a different approach. In the thermomechanical pulp (TMP) process, wood chips are fed into steam-heated refiners. These machines squeeze the chips between steel discs to create fibers. Another method is groundwood pulp (GW). This involves feeding debarked logs into grinders that use rotating stones. Mechanical pulping is very efficient, with a yield of over 95 percent. However, it does not remove the lignin. Because the lignin remains, this type of paper tends to turn yellow and become brittle over time.

Mäntän paperitehdas 1
Mäntän paperitehdas 1

Once the pulp is ready, it moves to a paper machine. The pulp is fed onto the machine to form a paper web. Water is removed through a process called pressing. This uses force to squeeze the liquid out of the sheet. A special kind of felt is used to collect the water. After pressing, the paper must be dried. In the past, people hung sheets to dry like laundry. Modern machines use steam-heated can dryers. These machines use long sequences of more than forty heated cans. This process can dry the paper until it has less than six percent moisture.

After drying, the paper can undergo sizing and finishing. Sizing involves applying a thin layer of material to the surface. Common materials include kaolin or calcium carbonate. This coating changes how the paper feels and prevents ink from running. The surface can also be polished through burnishing or calendering.

Coloured, textured craft card
Coloured, textured craft card

Finally, the paper is either cut into sheets or wound onto large reels. Most machine-made paper is "woven," meaning it has a consistent density along the paper grain.

The history of paper is quite long. Archaeological evidence shows paper-like materials existed in China during the 2nd century BCE. The pulp process is often credited to Cai Lun, a Han court eunuch in 105 CE. While papyrus was used in ancient Egypt, it was different from paper. Papyrus is a lamination of plant fibers, while paper is made through maceration. Paper eventually spread to the Islamic world and then to Europe by the 13th century. In Europe, the first water-powered paper mills were eventually built.

Chinese hemp paper western han
Chinese hemp paper western han

Industrialization changed everything in the 19th century. Before this, most paper was "rag paper" made from discarded textiles. In 1843, the invention of wood pulp changed the industry. Two inventors, Charles Fenerty from Canada and Friedrich Gottlob Keller from Germany, independently developed wood pulping processes. This made pulpwood paper the dominant variety used today. This shift greatly reduced the cost of making paper for everyone.

Today, we also use recycling to manage paper waste. De-inking is a process used to remove printing inks from old paper. This was invented by Justus Claproth in 1774. We can recycle mill waste, preconsumer waste from factories, or postconsumer waste from homes. While recycled paper is useful, it is often not as bright or strong as paper made from virgin pulp. Despite the rise of digital technology, paper remains vital. It is used for everything from books to paper money.

Money poster
Money poster
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🖼️ Images & Media (6)
File:Chinese hemp paper western han.jpg
Chinese hemp paper western han.jpg
File:PaperAutofluorescence.jpg
PaperAutofluorescence.jpg
File:Mäntän paperitehdas 1.JPG
Mäntän paperitehdas 1.JPG
File:20221129 low quality paper.jpg
20221129 low quality paper.jpg
File:Money poster.JPG
Money poster.JPG
File:Coloured, textured craft card.jpg
Coloured, textured craft card.jpg
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