Pine trees provide the primary source to make corrugated cardboard. After the trees are harvested, they  stripped off their limbs. Only their trunks are shipped to pulp mill. At the mill, the harvested tree trunks are subjected to the kraft process, which is known as the sulfate process. The chemical is used to break down wood chips into fibrous pulp. After processing, the fibers are put into the paper machine where they are formed, pressed, dried, and rolled into the wide rolls of kraft paper sent to corrugating plants to be made into cardboard.

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