Why must some recycled paper be de-inked before it can be used for printing-grade paper?

Recycled paper must be de-inked before it can be used for printing-grade or other white papers to ensure the final product meets the necessary standards for brightness, opacity, and surface quality.

When wastepaper is recovered for use in high-quality paper production, the presence of printing inks and other foreign materials—such as adhesives, coatings, and plastic films—can negatively impact the appearance and performance of the new sheet. The de-inking process is specifically designed to remove these contaminants. During this process, wastepaper is processed in a pulper with hot water and chemicals to disperse the fibres and separate them from the ink and other debris. The stock is then screened and washed to remove the dispersed ink particles and chemicals, often followed by bleaching to further enhance the whiteness of the pulp.1

In contrast, paper recovery intended for products like boxboards or coarse papers does not require de-inking, as the aesthetic requirements for these materials are less stringent.1