Creping

Creping is a finishing operation used in the manufacture of tissue, paper, and related sheet materials. In creping, a portion of the dried web is scraped from a rapidly rotating drying cylinder, typically a Yankee dryer, by a creping blade at a controlled angle. As the sheet detaches, it forms random micro-folds, producing a wrinkled surface and increased bulk. This change in texture is central to the characteristic softness and absorbency of many consumer papers.

Process and equipment

The creping process involves a heated drying surface (the Yankee dryer), a crepe blade (often called a doctor blade) positioned to peel the web away from the cylinder, and controlled tension and moisture conditions. Variables such as blade angle, blade pressure, substrate moisture, dryer speed, and the nipping conditions influence the degree of crepe and the resulting product properties. Variants include standard creping, microcreping (finer folds for a softer feel), and on-machine creping, where creping is integrated into the production line.

Effects and properties

Creping increases sheet caliper (bulk), softness, and absorbency, while modifying stretch and tensile behavior. The degree of creping is commonly described by a crepe factor, a dimensionless measure linked to bulk per unit weight. Trade-offs exist: higher creping improves hand feel and absorbency but can reduce strength and stiffness in the machine direction.

Applications

Creped products are widely used in consumer tissues such as bathroom tissue, facial tissue, and paper towels. Creping can also influence the performance of other paper grades where a softer, more pliable surface is desired.

See also

Crepe paper, tissue manufacturing, doctor blade, Yankee dryer.