Cardboard is the name of stiff paper that is more than .006 inch thick. The Chinese invented paperboard, or cardboard, over four-hundred years ago. According to "A Brief History of Packaging", by Kenneth R. Berger, published by The University of Florida, Institute of Food and Agricultural Sciences, the first cardboard box was produced in England in 1817. In the 1850's cardboard formed from corrugated paper was produced and used as packaging to ship products. This was a sturdier form of cardboard. Thin sheets of paperboard were molded into a wavy shape and then sandwiched between two flat pieces of paperboard.
Layers of Paper
Cardboard can be made by pasting layers of paper together. It can also be made by pressing layers of wet paper pulp together. There are different types of cardboard, such as strawboard, bending board, news board or bristol board. The name may be an indication of the materials used to produce the type of cardboard, or it may reflect a characteristic of the cardboard.
Corrugated cardboard that is considered single wall is similar to the cardboard created in the 1850's, in that it has the wavy center, with outer layers that are flat sheets. Corrugated cardboard that is considered double walled has two additional sheets, one wavy and one flat, to provide extra strength. When making the cardboard, rolls of paper are inserted into a corrugation machine that bonds the layers together with glue.
Corrugated cardboard is made from long and strong paper fibers. Because of this fact, corrugated cardboard can be recycled numerous times. Many recycling areas do not take cardboard that has been contaminated, such as cardboard with grease stains from pizza. While the general public typically refers to the material used to make such items as cereal boxes, cardboard, many recyclers consider that to be paperboard, which is made of a lower quality paper and does not have the wavy or fluted center.