HP Latex 3000 Printer - Manual (Page 286)

● Vacuum. In some thin substrates, if the vacuum is too high, the substrate follows the shape of the
platen ribs, modifying the printhead-to-substrate spacing and causing vertical line roughness. In this
case, as the substrate advances, vertical lines get wider after each pass, while horizontal lines are not
affected.
To correct this problem, try adjusting tension and vacuum settings according to the table below, step by
step (a to c), until you find settings that work.
Graininess
The print shows a higher level of grain than expected, either throughout the print or in some specific areas.
The example below shows more grain in the lower half than in the upper half.
This can occur for various different reasons.
● Coalescence. Some substrates, in some particular conditions, can produce a type of grain due to
wetting issues. For example, in high humidity or low temperature environments, the ink may not dry
fast enough in fast print modes, producing a grainy effect on the print. The example below shows worse
coalescence on the right-hand side.
280 Chapter 10 Troubleshoot print-quality issues ENWW