EN
Appendix B Media Specifications  139
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 
paper 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 
may 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 printer 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 printer environment is 
subject to extremes, unwrap only the amount of paper to be used 
during the day's operation to prevent unwanted moisture 
changes.