How Paper is Made
Paper is simple material. It is essentially a mat held together by the fiber’s roughness, and can be made from almost any fibrous material like wood or recycled paper.
The process of making paper has not changed – at least, fundamentally – since its discovery. But with almost two centuries of improvements and refinements, modern papermaking is a fascinating, high tech industry. Wisconsin has led the nation in papermaking for more than 50 years.
Typically, trees used for papermaking are specifically grown and harvested like a crop for that purpose. To meet tomorrow’s demand, forest products companies and private landowners in Wisconsin plant millions of new seedlings every year.
Step 2: Debarking, Chipping and/or Recycling
To begin the process, logs are passed through a debarker, where the bark is removed, and through chippers, where spinning blades cut the wood into 1″ pieces. Those wood chips are then pressure-cooked with a mixture of water and chemicals in a digester.
Used paper is another important source of paper fiber. Thanks to curbside recycling programs in many communities, we recover 40% of all paper used in America for recycling and reuse. The paper is shredded and mixed with water.
Step 3: Pulp Preparation
The pulp is washed, refined, cleaned and sometimes bleached, then turned to slush in the beater. Color dyes, coatings and other additives are mixed in, and the pulp slush is pumped onto a moving wire screen.
Computerized sensors and state-of-the-art control equipment monitor each stage of the process.
Step 4: Paper Formation
As the pulp travels down the screen, water is drained away and recycled. The resulting crude paper sheet, or web, is squeezed between large rollers to remove most of the remaining water and ensure smoothness and uniform thickness. The semidry web is then run through heated dryer rollers to remove the remaining water.
Waste water is carefully cleaned and purified before its release or reuse. Fiber particles and chemicals are filtered out and burned to provide additional power for the mill.
Papermakers carefully test for such things as uniformity of color and surface, water resistance, and ink holding ability.
Step 5: Paper Finishing
The finished paper is then wound into large rolls, which can be 30 feet wide and weigh close to 25 tons. A slitter cuts the paper into smaller, more manageable rolls, and the paper is ready for use.
Papermaking is one of the most capital intensive industries in the nation, investing over $100,000 in equipment for each employee. The largest papermaking machines are over 32 feet wide, 550 feet long and can produce over 1,000 miles of paper a day.