Probably the most common form of paperboard, medium and linerboard are the ingredients that form a corrugated box. While the linerboard provides the inner & outer wall, the medium forms the inside of the corrugated sheet and creates a wavy appearance called fluting, which gives the box its strength. Medium and linerboard are typically recycled paper, but can also be virgin/kraft as well. Linerboard can also be produced as a bleached/mottled-white or with a white clay coating for high-end printing. The majority of IPM's paperboard sales are in the area of containerboard. Due to our close relationship with mills, our offices source this product from mulitlple locations throughout the country.