HP LaserJet 9040/9050 Service Manual - Page 39

streaks and smudging. Humid weather or water coolers can cause the humidity in a room to increase. As a package of 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. Therefore, print-media storage and handling are as important as the paper-making process itself. Media storage environmental conditions directly affect the feed operation. Customers should not purchase more media than can easily be used in a short time (about three months). Media that is 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 media. Unopened paper in sealed packages 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 media storage environment should be properly maintained to ensure optimum printer performance. The required condition is 20°C to 24°C (68°F to 75°F), with a relative humidity of 45% to 55%. The following guidelines should be helpful when evaluating the paper-storage environment: z Paper should be stored at or near room temperature. z The air should not be too dry or too humid (because of the hygroscopic properties of paper). z The best way to store an opened package 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. Envelope storage Proper storage of envelopes contributes to good print quality. Envelopes should be stored flat. If air is trapped in an envelope, and creates an air bubble, then the envelope might wrinkle during printing. Paper weight equivalence table Use this table to determine approximate equivalent points in weight specifications other than U.S. bond weight. For example, to determine the equivalent of 20-lb U.S. bond-weight paper in U.S. coverweight paper, locate the bond weight (in row 3, second column) and scan across the row to the cover weight (in the fourth column). The equivalent is 28 lb. Shaded areas indicate a standard weight for that grade. Table 10. Paper weight equivalence U.S. postcard thickness (mm) U.S. bond weight (lb) U.S. text/ book weight (lb) U.S. cover weight (lb) U.S. bristol U.S. index weight (lb) weight (lb) U.S. tag weight (lb) Europe metric weight (g/m2) 17 43 24 29 35 39 64 Japan metric weight (g/m2) 64 20 50 28 34 42 46 75 75 21 54 30 36 44 49 80 80 22 56 31 38 46 51 81 81 24 60 33 41 50 55 90 90 27 68 37 45 55 61 100 100 28 70 39 49 58 65 105 105 32 80 44 55 67 74 120 120 34 86 47 58 71 79 128 128 36 90 50 62 75 83 135 135 0.18 39 100 55 67 82 91 148 148 0.19 42 107 58 72 87 97 157 157 0.20 43 110 60 74 90 100 163 163 Media specifications 23