Paper mill operations are an industry not often recognised, but it is an important one. Paper mills transform raw plant fibers into sheets or packaging, and are the source of books, boxes, receipts, tissues and printer paper.

Today, the preferred fiber is wood. The bark is removed from logs, which are chipped. The chips are then turned into pulp, a slurry of cellulose. Pulp can be produced in two ways. Mechanical pulping breaks down the wood and retains much of it, so it can be used for things such as newsprint. Chemical pulping dissolves the lignin that glues wood fibers together. This results in high-quality pulp suitable for writing paper and packaging.

Once the pulp is created, it's washed and screened to clean it up. Paper manufacturers can also add dyes, fillers or coatings, if needed. Old paper is also added. Recycling paper can be separated in water, ink removed, and added to make new products, saving resources and eliminating waste.
The pulp is then mixed with water and applied to a moving wire screen. The fibres form a sheet as water drains through the screen. It is run through some rollers to press out water and then dried in a series of hot dryers.

Finally, the paper is flattened, coiled or cut. Some are given special coatings for brightness and printing. Other types are converted to cartons, paper towels, or even notebook paper.
Paper mills are also environmentally responsible. They employ recycled material, alternative energy sources, and environmentally-friendly forest management.

Paper is still crucial in the digital era. Paper is vital for packaging, food boxes, books, labels and personal hygiene. This humble sheet is a product of engineering and mass manufacturing.