HP LaserJet M4349 Multifunction Printer series - Manual (Page 91)

Printing and paper-storage environment
Ideally, the printing and paper-storage environment should be at or near room temperature, and not too
dry or too humid. Remember paper is hygroscopic; it absorbs and loses moisture rapidly.
Heat works with humidity to damage paper. Heat causes the moisture in paper to evaporate, while cold
causes it to condense on the sheets. Heating systems and air conditioners remove most of the humidity
from a room. As paper is opened and used, it loses moisture, causing streaks and smudging. Humid
weather or water coolers can cause the humidity to increase in a room. As paper is opened and used
it absorbs any excess moisture, causing light print and dropouts. Also, as paper loses and gains moisture
it can distort. This can cause jams.
As a result, paper storage and handling are as important as the paper-making process itself. Paper
storage environmental conditions directly affect the feed operation.
Care should be taken not to purchase more paper than can be easily used in a short time (about 3
months). Paper stored for long periods might experience heat and moisture extremes, which can cause
damage. Planning is important to prevent damage to a large supply of paper.
Unopened paper in sealed reams can remain stable for several months before use. Opened packages
of paper have more potential for environmental damage, especially if they are not wrapped with a
moisture-proof barrier.
The paper-storage environment should be properly maintained to ensure optimum product performance.
The required condition is 20° to 24°C (68° to 75°F), with a relative humidity of 45% to 55%. The following
guidelines should be helpful when evaluating the paper's storage environment:
● Paper should be stored at or near room temperature.
● The air should not be too dry or too humid (due to the hygroscopic properties of paper).
● The best way to store an opened ream of paper is to rewrap it tightly in its moisture-proof wrapping.
If the product environment is subject to extremes, unwrap only the amount of paper to be used
during the day's operation to prevent unwanted moisture changes.
● Proper storage of envelopes helps contribute to print quality. Envelopes should be stored flat. If air
is trapped in an envelope, creating an air bubble, then the envelope might wrinkle during
printing.
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