Why must different types of wastepaper usually be sorted before recycling?

Sorting different types of wastepaper is essential for effective recycling because paper products vary significantly in their composition, quality, and intended end-use.12

The primary reasons for sorting include:

• Material Compatibility: Different papers are processed into specific products. For instance, newsprint and cardboard are often repulped to create the same materials, while other scrap papers are better suited for lower-quality products like boxboard, tissues, and towels.2
• Contamination and Additives: Modern paper products often contain coatings or ingredients—such as synthetic adhesives, asphalt, metal foils, plastic films, and various printing inks—that can interfere with the recycling process. Sorting allows for the removal of these "objectionable materials" that would otherwise degrade the quality of the recycled pulp.1
• Processing Requirements: Recovery systems differ based on the paper grade. Paper intended for high-quality printing must undergo a de-inking process using chemicals like caustic soda, whereas other grades, such as those used for coarse papers, do not require this step.12

Proper segregation at the source ensures that mills can efficiently recover usable fibers while maintaining the necessary standards for the final product.1