How paper is made?

Paper is made by turning wood or other plant fibres into pulp, cleaning it, spreading it into a thin sheet, removing all that extra water and then pressing and drying it.

Basically, the process goes like this:

Wood/Fibre → Pulp → Cleaning → Sheet Formation → Pressing → Drying → Finishing → Paper

It is actually intriguing to me how something as solid as wood ends up becoming a smooth page of a notebook. We use paper so casually—writing on it, printing on it, sometimes crumpling and throwing it away—that we barely think about where it came from.

Raw Material

Most paper starts with cellulose fibre, and wood is one of its most common sources.

At a paper mill, wood logs are first stripped of their bark and cut into small chips. Smaller pieces are obviously much easier to break down than putting an entire log into a machine and hoping for paper to come out.

Wood isn't the only option, though. Paper can also be made from recycled paper, bamboo, cotton, straw and bagasse, which is the fibrous material left after extracting juice from sugarcane.

Pulping

Now those wood chips need to somehow stop being wood.

That's where pulping comes in.

The chips are processed mechanically or with chemicals to separate the cellulose fibres. In chemical pulping, chemicals and heat help remove lignin, the substance that basically holds the fibres together in wood.

What you get after this isn't a nice white sheet. It's a wet, mushy mixture called pulp.

Honestly, if you saw only this stage without knowing the process, paper probably wouldn't be your first guess for what it's going to become.

Cleaning

The pulp can contain bits of bark, dirt and other unwanted material, so it needs to be cleaned and screened.

If white or brighter paper is being produced, the pulp may also be bleached.

This step changes depending on what's being made because newspaper, cardboard and the white A4 sheets sitting beside your printer obviously don't need to look or feel the same.

Sheet Formation

This is the part where pulp finally starts becoming paper.

The cleaned pulp is mixed with a lot of water and poured onto a moving mesh screen. The water drains through it, but the tiny fibres stay on top.

Those fibres start coming together and form one continuous, very wet sheet.

So strangely enough, paper doesn't begin as a dry sheet at all. At one point, it's mostly water.

Pressing

That wet sheet then passes through heavy rollers.

The rollers squeeze out more water and press the fibres closer together. This also makes the paper flatter and stronger.

You can almost think of this stage as taking that loose wet layer and finally giving it some proper structure.

Drying

There is still moisture left, so the sheet moves over heated cylinders that dry it further.

By the time it comes out of this section, it finally looks much closer to the paper we actually recognise.

And when you see those massive rolls of paper coming out of a paper machine, it's kind of hard to connect them back to the pile of wood chips the process started with.

Finishing

Paper isn't necessarily ready just because it's dry.

Depending on what it will be used for, manufacturers may smooth it, coat it, colour it or cut it into different sizes.

That's how we end up with such different products—newspapers, notebooks, glossy magazines, tissues, packaging and printer paper—even though the basic paper-making process is quite similar.

Recycling

Old paper can go through the process again.

It is collected, sorted and mixed with water to make pulp. Ink, staples, glue and other unwanted materials are removed before the fibres are used for new paper.

But here's something I didn't know earlier: paper cannot be recycled forever.

Every time cellulose fibres are recycled, they become shorter and weaker. After several cycles, they aren't strong enough to make good paper anymore, so fresh fibres have to be mixed in.

FAQs

Is paper made only from trees?

No. Paper can also be made from recycled paper, bamboo, cotton, bagasse, straw and other plant fibres.

What is pulp in papermaking?

Pulp is the wet mixture of separated cellulose fibres that is eventually formed into paper.

Why is paper pressed?

Pressing removes excess water and helps bind the fibres into a flatter, stronger sheet.

Why does paper need to be dried?

Even after pressing, the sheet contains moisture. Heated cylinders remove that remaining water.

Must Read: What is recycling of paper?