The arrangement of fibers in a sheet of paper, which can be seen by holding a sheet of paper to the light source.  The formation is determined by composition of the fibers, fiber length, machine speed and other factors.  

Formation can run from "tight" to "wild" and is a major factor in determining how the sheet will perform, affecting factors like levelness, strength and dimensional stability.

Last updated on January 29, 2010 by Joshua Levine