Important System Information And Limitations - HP IndiChrome User Manual

Important system information and limitations

ENWW
The following procedures take some time to accomplish:
• Cleaning and preparing the ink tank may take between 40 and 60 minutes. You can
save 20 minutes on the Series 3000/4000/5000 or UltraStream-based press if you
use a replacement BID, ink pump, and ink tank.
• Ink formulation may take between 30 minutes (for one step) and 100 minutes (for
three to four steps).
Color accuracy:
• Gamut: In some cases, the target color may be outside the gamut of the
HP IndiChrome ink mixing system. This situation is characterized by having the
predicted best mix color differ from the target by a ∆E*
situation, the software guides you to achieve the mix that best resembles the target
color, regardless of what the predicted ∆E*
• Gloss: When the gloss of the target color sample is substantially different from the
printed color, it may be difficult to visually compare the two colors. For a glossier
target you can overcoat or laminate the printed sample with a glossy substance
before the comparison. You can even manually apply some imaging oil onto the
surface of the color to get the required temporary increase of the gloss or laminate
the sample with a transparent glossy scotch tape.
• Grey shades: In Sun computer-based presses with off-line densitometers, the LUT
of the custom color is the same as the LUT of Black. Therefore, the color shades
may not appear as linear as they should be.
• Double print: The HP IndiChrome ink mixing system software may suggest that
you formulate the ink for double printing. This occurs when the best mix color in
single print is not bright enough. If you print the separation of such ink twice, the
solid color effect is accurate but the color shades are not. Therefore, double print
should be used for printing solids only. If you double print shades, they are not
linear.
• Hot lamination: The printed colors may change during hot lamination, which may
be required when preparing PVC cards.
Mixing procedure:
• Ineffective mix: Some of the fix corrections may not improve the color. This reflects
the statistical nature of the corrective algorithm. In such cases, you may still expect
improvement of the color in successive corrections.
• Inaccurate mix: The color of the actual mix usually differs from the target color
more than the software prediction shows. This is mainly because of minute
contamination in the ink tank, inaccurate dispensing of the basic inks into the mix
can, and specific characteristics of the substrate in the print run. This is especially
true with colors that are outside the gamut.
• Precision in color adjustment: During the ink formulation stage, you are instructed
to correct the color by printing again with a modified optical density (OD) value.
Because of the limited precision of the color adjustment procedure, this instruction
may be repeated until the OD, as read by the spectrophotometer, is as required.
• Resending the ink parameter file: Do not send the ink parameter file to the press
more than once. If for some reason this has been done, you should use a first can
for recalibrating the ink density sensor.
of more than zero. In this
94
is.
94
Important system information and limitations 17