This may be just a temporary problem: try reprinting, and perhaps slightly reduce the ink limits. It may
be worth adjusting the print queue so that the first job is not difficult to cure (uses a lot of ink).
●
When the symptoms can be seen only in certain parts of the print that use a lot of ink
Increase the curing temperature, decrease the overall ink quantity, increase the number of passes,
and/or modify the inter-path delay offset (in the RIP or front panel) to allow better drying on
consecutive passes.
●
When the symptoms appear after reducing the number of passes
Increase the curing temperature, decrease the overall ink quantity, and/or modify the inter-path delay
offset (in the RIP or front panel) to allow better drying on consecutive passes.
●
When the oily finish appears minutes or hours after printing
Store the print face-up and uncovered; the effect normally disappears after a while.
NOTE: If you decrease the overall ink quantity, you may notice less color saturation.
The dimensions of the print are wrong
As the substrate is heated during the curing process, some substrates will shrink (and some may expand)
after the image has been printed. This may be inconvenient if the print has to be framed or if several prints
are to be to be tiled one next to the other.
See
The substrate has shrunk or expanded on page 83.
Tiling issues
The most common problems when printing tiles are as follows.
●
Color variation tile-to-tile
In some cases, contiguous tiles with the same background solid color may show differences in color
between the right side of the first tile and the left side of the second tile. This is a common issue of
inkjet printers (both thermal inkjet and piezo inkjet), where there are slight color variations as the swath
advances.
To improve color consistency side-to-side and tile-to-tile, try adding color bars at the side of the print.
These can be set from the RIP.
Since the biggest color differences are between the left edge and the right edge, the effect may
sometimes be seen when putting two tiles together. This issue can easily be overcome by inverting
alternate tiles, which has the effect of placing the right side of the first tile next to the right side of the
second tile and the left side of the second tile next to the left side of the third, so all contiguous areas
have been printed in the same point of the swath and, hence, have the same color. This is a feature that
all RIPs have available.
●
Dimensional variations from tile to tile
Some specific banner substrates may not have uniform dimensional stability when printing very long
tiles. The result is that the length of the tile may be different between the left and the right side (for
instance, a 9-meter-long tile may be about 1 cm longer on the right than on the left side). While this is
not noticeable with individual plots, it affects the alignment between panels in tiling applications.
Substrate types that show this behavior tend to show it constantly along the roll. So, when present, this
issue can easily be overcome by inverting alternate tiles as described above.
●
In bidirectional printing, minor differences in tone may be noticed on close inspection
This happens because the drying times are not the same across the scan axis. Adding a small inter-path
delay offset of about 0.5–1 second may give better results.
ENWW Most-common print-quality problems 117
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