TAPPI T 274 sp-13:2013 Edition

A general purpose practice for screening pulp using a specific
screening device is described, which separates from a slurry of
pulp fibers a contaminant fraction with size dimensions which are
significantly greater than the diameter of a pulp fiber.

Separated contaminants include, but are not limited to, shives
in virgin fibers, or macro stickies that are captured by the
barrier screen plate, scleroids, dirt, stone cells, plastics,
pitch, white pitch, and other contaminants in virgin and recycled
fibers.

There are numerous screening instruments used for separation,
classification, or quantitation of contaminants from pulp fibers,
including T 278 "Pulp Screening (Valley-Type Screening Device)" and
T 275 "Screening of Pulp (Sommerville-Type Equipment)." This
procedure covers a specific screening procedure to concentrate
contaminants by fiber removal, and does not cover use of screens
for pulp size classification.

While this practice does not describe the specific procedure
required to quantitatively measure the contaminant fraction
separated, it should be noted that where this is done by the user
of this practice, slightly different quantitative results may be
found among or between results calculated using the device
described in this Practice and the various devices in 1.3.