precreping

Precreping is a manufacturing process used in the production of paper, particularly for the production of specialized papers such as filter papers, cigarette papers, and other non-standard papers.

The precreping process involves taking a fourdrinier wire mesh, which has been filled with a layer of pulp, and then cutting a series of parallel creases into the pulp layer. This is done before the pulp layer has dried, typically before it has been pressed or dried. The creases are made using a creping blade, which can take one of several forms depending on the specific manufacturer and production requirements.

The primary function of precreping is to create a weakened area in the paper product that will allow it to separate or "creep" more readily when needed. This is particularly useful in papers that are subject to high levels of stress or that need to be able to expand or contract without breaking. For example, filter papers used in scientific applications often need to be able to expand to allow certain chemicals to pass through while remaining intact.

As the precreped pulp passes through a series of rolls, the weakened areas created by the creping blade are further emphasized, creating a sheet of paper that is more prone to creeping than non-precreped paper. This is highly desirable in applications where paper needs to exhibit unique properties, such as rapid drying or the ability to expand and contract easily.