[Infographic] How a Tree Becomes a Box

An inside look at how a tree becomes a box

Did you know that boxes are made from almost 100% raw materials? Fast-growing pine trees provide the primary raw material used to make corrugated cardboard. The largest packaging companies own thousands of acres of land where trees are matured, harvested, and replaced with seedlings.

After the trees are harvested, they are stripped of their limbs and the trunks are prepared to be shipped by truck to a pulp mill.

At the pulp mill, pulping and processing is used to break down wood chips into fibrous pulp. Tree trunks are stripped of bark and torn into small chips. These chips are placed in a large, high-pressure tank called a batch digester, where they are cooked in a solution, or liquor, made of sodium hydroxide (NaOH) and several other ionic compounds such as sulfates, sulfides, and sulfites. These strongly alkaline chemicals dissolve the lignin, the glue-like substance that holds the individual wood fibers together in a tree trunk. When the pressure is released after several hours, the wood chips explode like popcorn into fluffy masses of fiber.

The fibers are sent directly to the paper machine where they are formed, pressed, dried, and rolled into the wide, heavy rolls of kraft paper. After additional cleaning and refining steps, a consistent slurry of wood pulp is pumped to the paper-making machine. Gigantic, square structures up to 600 feet long, these machines contain a wire mesh in which the paper is initially formed.

Next, the paper is fed into massive, steam-heated rollers and wide felt blankets that remove the water. At the end, the finished medium, or liner, is rolled for shipment.

Kraft paper is sent to corrugating plants to be made into cardboard. At the corrugating plant, corn starch glue is used to bond the corrugated medium to the liner sheets. Drawn from a large silo, the dry corn starch is mixed with water and other chemicals and pumped into the corrugator to be spread on the corrugated medium as the layers of liner are added.

After the corrugator has heated, glued, and pressed the kraft paper to form corrugated cardboard, the continuous sheet of cardboard is cut into wide box blanks that then go to other machines for printing, cutting, and gluing. Finally, batches of finished boxes are banded together for shipping to the food processor, toy maker, automobile parts distributor, or any of the thousands of businesses that depend on corrugated cardboard packaging.

Other raw materials are used to finish the corrugated cardboard after production for design and functional purposes.

Lastly, because packaging products are made of almost 100% raw materials, once they are finished being used they can be recycled at any paper recycling center to be made into a box, or another recycled good.