Paperboard, also boxboard or containerboard, is thick paper used in the production of cardboard. Cardboard is just the popular and generic name when referring to corrugated fiberboard – the building block of small cardboard boxes. In the production process, a mixture of recycled and virgin fibrous material is turned into pulp and then layered into boards to achieve needed strength. Additionally, it can be bleached to achieve the printing qualities and market appearance.

Pulping can be mechanical or chemical. Mechanical pulping is done by means of industrial machinery; it is highly efficient and outputs high percentage of fibers. Chemical pulping uses chemicals to turn wood into pulp and it yields about a third less than mechanical pulping.

Bleaching becomes necessary when the ratio of recycled versus virgin fibers in the pulp goes up. Certain markets are state regulated as to amount of recycled fibers which have to be utilized in the production of paper and small cardboard boxes. Often the recycled fibers contain leftovers of adhesive, plastic, inks etc. These cause the color of paperboard to lean towards grey and deteriorate its printing qualities. To comply with the legal requirements, manufacturers use various gasses and chemical methods of bleaching according to the color quality needed:

• Delignification – this method uses chlorine gas and can be disruptive to the environment
• Oxidation – pure chlorine gas is replaced by chlorine dioxide, sodium hypochlorite and hydrogen peroxide. This achieves similar effect at a lesser environment impact
• Reduction – use of sodium bisulphate

Furthermore, paperboard is classified based on the pulp origin:

• Solid unbleached board – manufactured from unbleached pulp
• Solid bleached board – mostly virgin fiber is used from bleached pulp
• Folding box board –contains a layer of mechanical pulp for extra strength
• White lined chipboard – mostly grey, with both virgin and recycled fibers used in the manufacturing process

At the end of the production cycle paperboard is rolled into large spools and shipped to factories for the production of small and large cardboard boxes. They are done according to market demand and customer specifications. More considerations on this topic together with latest on cardboard boxes can be found at www.smallcardboardboxes.org