linerboards

Linerboard refers to the flat paper sheets that form the outer layers of corrugated cardboard. In a standard corrugated board, a fluted sheet is sandwiched between two linerboards, creating a strong, printable panel used for shipping boxes, displays, and protective packaging.

Materials and grades: Linerboard is primarily made from wood pulp via the kraft process, producing kraft linerboard known for high strength and durability. Recovered fibers from old corrugated containers (OCC) are also used to produce recycled linerboard, which generally has lower strength but improved environmental performance. White-top linerboard has a lighter exterior with a white surface for better print quality. Other grades, such as test liner, use varied fiber blends. Basis weight is typically stated as pounds per thousand square feet (PSF) or grams per square meter (GSM) and is selected to meet strength and cushioning requirements.

Properties and performance: The linerboard’s weight, thickness, and fiber composition influence the board’s edge crush resistance, burst strength, and moisture response. The combination of linerboard and medium defines the box’s performance class and determines suitability for different contents and shipping conditions, including tests such as edge crush or burst strength ratings.

Manufacturing and use: Linerboard is produced on papermaking machines, dried, calendered, and rolled for corrugation. A corrugator bonds linerboards to the fluted medium with adhesive, forming continuous sheets that are cut, creased, and converted into boxes, displays, or other packaging products.

Environmental and industry context: Linerboard can be virgin kraft or recycled content. Corrugated board is widely recyclable and often used in a circular economy. Manufacturing standards and packaging guidelines emphasize recyclability, recycled content, and forest-sustainability considerations, with many suppliers aligning to TAPPI standards and industry practices.