Paper recycling is the process of turning used paper and cardboard into new paper products. It involves collecting, sorting, cleaning, and repulping old paper so the plant fibers inside can be formed into fresh sheets, boxes, and packaging. In the United States, paper has the highest recycling rate of any material in the waste stream, with 68.2 percent of all paper and paperboard recovered in 2018, totaling roughly 46 million tons.
How the Process Works
Paper recycling follows a relatively straightforward path from your bin to a new product. After collection, paper arrives at a materials recovery facility where it’s sorted by grade. Corrugated cardboard, newspapers, office paper, and mixed paper each have different fiber qualities and end uses, so separating them early matters. Modern facilities use optical sorters equipped with near-infrared sensors and AI to identify different paper types and pull out contaminants like plastic film or metal at high speed.
Once sorted, the paper is baled and shipped to a paper mill. There, it’s mixed with water in a large vat called a pulper, which breaks the paper down into a slurry of individual cellulose fibers. This is essentially the reverse of papermaking: you’re turning a solid sheet back into the soupy pulp it started as.
The slurry then goes through cleaning stages to remove staples, tape, plastic bits, and glue. For paper that needs to be white or printed on again, a de-inking step follows. In flotation de-inking, air bubbles are pumped through the pulp. Ink particles are hydrophobic, meaning they cling to bubbles rather than staying in the water. The inked bubbles float to the surface and get skimmed off as froth, leaving cleaner fibers behind. This same technique is increasingly used to remove sticky adhesive residues.
After cleaning, the pulp is spread onto screens, pressed, and dried into new paper. Mills often blend recycled fibers with some percentage of virgin wood pulp to control the strength and smoothness of the final product.
What Recycled Paper Becomes
Different grades of recovered paper feed different products. Old corrugated containers (the brown cardboard from shipping boxes) get turned back into new shipping boxes and recycled paperboard for cereal boxes, shoe boxes, and similar packaging. Corrugated cardboard has by far the highest recovery rate of any paper category at 96.5 percent. Old newspapers primarily become new newsprint, tissue products, or paperboard. Mixed paper, a broad category that includes junk mail, phone books, catalogs, and magazines, typically goes into lower-grade products like paperboard or construction paper.
The grade system matters because fiber quality varies. Office printer paper has long, strong fibers and can become high-quality recycled paper. Newsprint fibers are shorter and weaker, limiting what they can become. This is why recycling programs ask you to keep cardboard separate from mixed paper when possible.
How Many Times Fibers Can Be Recycled
You may have heard that paper can only be recycled four to seven times before the fibers become too short and weak to hold together. That figure is outdated. Research from the paper packaging industry has demonstrated that cartonboard fibers can be recycled more than 25 times with little to no loss of integrity. In practice, most paper doesn’t go through that many cycles because some fiber is lost during each round of cleaning and de-inking, and the global paper supply constantly adds fresh virgin fiber to the mix. But the biological limit of the fiber itself is far higher than most people assume.
Energy and Resource Savings
Making paper from recycled stock uses 25 to 75 percent less energy than making it from virgin wood pulp, depending on the paper type and mill efficiency. Newsprint offers a clear example: producing a ton from virgin pulp requires about 30 million BTUs of energy, while making it from recovered newsprint takes roughly 10 million BTUs, a 67 percent reduction. Beyond energy, recycling paper reduces the number of trees harvested, cuts water consumption during manufacturing, and diverts a massive volume of material from landfills. Paper and paperboard account for 23.1 percent of all municipal solid waste generated in the U.S., making it the single largest category by weight.
Paper You Can’t Recycle
Not everything made of paper belongs in the recycling bin. These common items cause contamination problems at the mill:
- Paper cups and plates, including coffee cups, which have a thin plastic or wax lining that can’t be separated from the fiber in standard pulping
- Napkins, facial tissues, toilet paper, and paper towels, which have fibers too short and degraded to repulp, and are often contaminated with moisture or food
- Wax paper, because the wax coating doesn’t dissolve during pulping
- Thermal paper receipts, which contain chemical coatings that contaminate the recycled pulp
- Shiny gift bags and gift wrapping tissue, often made with metallic films or dyes that can’t be removed
- Food-soiled paper like greasy pizza boxes or used takeout containers, where oil saturates the fibers and interferes with bonding in new paper
When these items end up in a recycling load, they can contaminate an entire batch of otherwise usable fiber. This is one of the biggest practical challenges in paper recycling. A clean stream of sorted paper is worth significantly more to a mill than a mixed load full of contaminants.
How Sorting Has Changed
The sorting stage has evolved dramatically in recent years. Older facilities relied almost entirely on manual labor, with workers pulling contaminants off a moving conveyor belt. Modern plants still use human sorters, but the heavy lifting increasingly falls to optical sorting machines. These systems use near-infrared spectroscopy to identify the chemical composition of materials moving past at high speed, distinguishing paper from plastic, cardboard from mixed paper, and clean fiber from contaminated fiber. AI-powered systems from manufacturers like TOMRA use deep learning to improve accuracy over time, significantly reducing the contamination that reaches the mill.
This technology matters because contamination is the main bottleneck in paper recycling. The cleaner the sorted output, the higher the quality of the recycled product and the more economically viable the entire process becomes.