HP D640 Bedienungsanleitung PDF herunterladen (Seite 238)

Paper Manufacturing

D-2 Using Paper

In the United States, Hewlett-Packard also offers support through a local support

representative. A customer support technician will be happy to offer advice to help solve your

printer operation problems.

Paper Manufacturing

Laser printers require paper types and specifications that were uncommon just a decade ago.

Until then, no distinction was made between writing paper and xerographic paper. The

manufacture of paper is complex. Several different mills may offer the same type of paper (for

example, 25% cotton bond, writing stock) but each manufacturer will vary the texture, color,

fiber, lignin, coating, and other elements which make their product unique. In the paper

industry, there are no equivalent papers between manufacturers, only substitutes.

Sources of Paper

Paper is primarily made from cellulose fiber, the major component of the cell walls of wood

fibers and other plants. Sources of this fiber include:

• Raw Wood

• Recycled or waste wood

• Cotton

Pulping methods are based, in part, on the fiber length of the raw wood. Hardwoods, such as

cottonwood, contain short fibers, from one to two millimeters in length. Softwood fibers,

including pine, spruce, and other conifers range in length from three to six millimeters. In each

case, the thickness is less than that of a human hair.

These differences often mean variability among paper manufacturers, even within the same

company. To ensure quality and consistency, a certain percentage of this material must come

from raw wood. Timber may be harvested from national forests and private land as well as tree

farms or plantations.

Surface Coatings

A thin layer of coating may be applied to the paper which could change its physical

characteristics. These surface coatings or “sizings” are added to make the sheets more resistant

to ink or water penetration and to increase durability. Coatings may also be added to create a

neutral pH in paper used for archival storage (such as legal documents). Surface coatings are

usually liquid starches and are applied either by spraying, immersion, or mixing into the

furnish.

Heavy coatings of clay or talc should be avoided because they become hard and brittle, causing

the fibers to break like a piece of chalk and come off during printer operation. Surface coatings

also affect the surface electrical resistivity, which is a important factor in the performance of

your D640 printers.

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HP D640 Bedienungsanleitung Seite 238