pass. Today's âstandardâ system often requires the use of multiple white stations on press, or more expensive, refor
Delivering a Whiter White in Package Printing A White Paper
Delivering a Whiter White in Package Printing
Executive Summary
“Digital
MWW is a flexographic printing plate that brings unparalleled print performance to white ink delivery, providing dramatically reduced mottle and improved opacity - all in one pass.”
Digital MWW is a flexographic printing plate that brings unparalleled print performance to white ink delivery, providing dramatically reduced mottle and improved opacity- all in one pass. Today’s “standard” system often requires the use of multiple white stations on press, or more expensive, reformulated inks just to achieve acceptable values. The use of Digital MWW in combination with the LUX® exposure process and the WhiteFXTM ink transfer solution developed by CSW, Inc., allows for dramatic improvements in print quality and reduces overall white ink consumption.
Part I: The Beginning Digital MWW was an outcome of a designed experiment conducted by the combined research departments of MacDermid Graphics Solutions and CSW, Inc. The “White Print Matrix” project was prepared with a technical presentation at FFTA Info*Flex in mind. In conceiving the project, MacDermid and CSW sought to converge the capabilities of LUX® flattop dot technology, advanced surface engineering techniques, and the on-press knowledge for printing background whites. The end result was the experimental outline shown in Table 1. Table 1: Experimental Layout for the White Print Matrix
Delivering a Whiter White in Package Printing
The print layout shown in Figure 1 was selected in order to optimize the efficiency and objectivity of the study. The study was conducted on a 50” wide web press, utilizing four printing decks, three anilox types, and multiple sleeves. The white ink formulation was kept constant, with a closely monitored and maintained viscosity typical for high speed production. Shrinkable polyethylene was chosen for the substrate due to its common use in wide web production. In addition, an overprint of cyan was added to the study in order to evaluate the potential impact of background white on other aspects of the print. Figure 1: Print Layout
The final print layout is shown below in Figure 2. During this study, three different plate and tape hardnesses were evaluated, in addition to three selections of anilox rolls (250, 360 and 550). Four different screening methods were employed on two different types of digital plates, which included LUX® and standard exposure methods.
Delivering a Whiter White in Package Printing
Figure 2: Test Form
The Results After running 270 different combinations, the results were analyzed for optimum mottle and opacity, with a “standard” method as reference. This standard method was a double print white using a medium durometer, conventionally exposed digital plate. It became evident early on that the LUX® exposed plates greatly enhanced the impact of surface screening methodologies, an observation seen in other print applications as well. The pictures shown in Figure 3 highlight the various levels of print quality seen in this study. As shown, the study was indeed effective in including numerous “poor” quality results in addition to remarkably high quality results as well.
Delivering a Whiter White in Package Printing
Figure 3: Comparison of Various Mottle Levels Observed in the White Print Matrix
In addition to the noticeable impact on the white samples alone, the inclusion of the overprint cyan showed what a dramatic impact that the background white can have on other colors as well. Figure 4 shows the same four levels in the presence of the overprint color. Figure 4: Impact of Background White Mottle on Overprint Cyan
Delivering a Whiter White in Package Printing
Overall, significant improvements were noted in both opacity and mottle, but the question remained as to how to select the best of the best. The table below shows the weighted outcome of mottle using values less than 6. It should be noted that white poly has a mottle value less than 1. Out of the 270 scenarios evaluation, a total of 20 samples met the criteria of mottle less than 6. Furthermore, all of these values were obtained with the 250 and 360 anilox rolls, with 60% of the optimized results belonging to the 250 anilox. Table 2: Final Mottle Tabulation MOTTLE
250 ANILOX - 7.2 bcm
360 ANILOX - 5.0 bcm
550 ANILOX - 2.5 bcm
TOTALS
0 - 2.99
OPTIMUM
6
OPTIMUM
3
OPTIMUM
0
9
3 - 5.99
GREAT
6
GREAT
5
GREAT
0
11
6 - 10.99
GOOD
10
GOOD
9
GOOD
0
19
11 - 15.99
BETTER
19
BETTER
11
BETTER
1
31
16 - 19.99
NORMAL
19
NORMAL
9
NORMAL
0
28
20 - 25.99
POOR
18
POOR
16
POOR
1
35
26 - 29.99
BAD
10
BAD
19
BAD
2
31
30+
UNUSABLE
2
UNUSABLE
18
UNUSABLE
86
106
90
270
TOTALS
90
90
Similarly, the opacity values were tabulated and are shown in Table 3. In this case, samples with opacity values greater than 54 were highlighted, yielding a final total of 48 samples. Of these 48, 47 were attributable to the highest volume anilox configuration, with only one sample belonging to another anilox roll selection.
Delivering a Whiter White in Package Printing
Table 3: Final Opacity Tabulation OPACITY
250 ANILOX - 7.2 bcm
360 ANILOX - 5.0 bcm
550 ANILOX - 2.5 bcm
TOTALS
>55
OPTIMUM
4
OPTIMUM
0
OPTIMUM
0
4
54 - 55.9
GREAT
43
GREAT
1
GREAT
0
44
52 - 53.9
GOOD
39
GOOD
23
GOOD
0
62
50 - 51.9
BETTER
4
BETTER
40
BETTER
0
44
