The Origin of Offset Printing Paper

A premium paper suitable for offset lithography. It requires a smooth, fine texture with uniform fiber structure and minimal, consistent dimensional stability—particularly in the cross-direction—to ensure accurate registration and sharp image reproduction during multicolor printing. The primary raw material is bleached wood pulp, supplemented with bleached cotton pulp, bamboo pulp, or rice/wheat straw pulp as regional resources permit. It is typically produced on a fourdrinier paper machine. The pulping method primarily uses free-fiber pulping with moderate beating degree. Emphasis is placed on optimizing forming section conditions to achieve uniform fiber structure and rational longitudinal/transverse fiber alignment. Selecting appropriate press felt types prevents noticeable blanket marks. To minimize lint and powder shedding during printing, surface sizing with polyvinyl alcohol or oxidized starch is common. Available in both roll and sheet forms, grades (Special, No. 1, No. 2) vary based on pulp composition and calendering methods, with basis weights ranging from 70 to 180 g/m².

Paper for printing New Year paintings, propaganda posters, and trademark advertisements is predominantly single-sided offset printing paper, also known as “poster paper.” It is dried in a single pass through a large-diameter gloss-finishing cylinder. Commercially named “base paper” and ordinary “illustration paper” both fall under the category of double-sided offset printing paper.