HP d640 HP D640 High-Volume Printer - User Manual (Printer and Accessories), C - Page 247

Using Paper General Guidelines Table D-4 Recommended paper specifications Parameter Specification Stiffness (Clark Method) Printing direction: 90 ± 25 Cross direction: 40 ±15 Fusing Compatibility Opacity Must not scorch, melt, offset, or release hazardous emissions when heated to 392° F (200°C) 84% ± 3% Wax Pick 12 minimum (Dennison) Grain Letter / A4 is best with short grain For all other sizes, use long grain Pre-printed Forms and Letterhead To avoid multiple feeding and jamming problems when using pre-printed forms, embossed paper, and letterhead, observe the following guidelines: • Do not use low-temperature inks (the kind used with some types of thermography). • Use forms and letterhead printed by offset lithography or engraving. • Forms must be printed with heat-resistant inks that will not melt, vaporize, or release hazardous emissions when heated to 392°F (200°C) for 0.1 second. Typically, oxidationset or oil-based inks meet this requirement. • If oxidation-cured inks are used, the use of oxidation retardants should be minimized. • When the form is pre-printed, be careful not to change the moisture content of the paper, or use materials that change the paper's electrical or handling properties. Forms should be sealed in moisture-proof wrap to prevent moisture changes during storage. • Pre-printed forms should not be processed with a finish or coated at the end of their production. • Do not use heavily embossed or raised letterhead papers. • Avoid papers with heavily textured surfaces. • Avoid using a band of ink on the leading edge of the paper. • Water additives must not be used, as they change the conductivity of the paper. The effect of the electrical charge applied to the paper during the printing process may be altered. • Following offset printing, the printed pages should be allowed to dry for one to two weeks in an atmosphere of 60°F to 80°F (16°C to 27°C) with a relative humidity of 35% to 50%. Using Paper D-11