What's the best order to print the four colors in four-color process? A definitive conclusion has eluded even the most technical screen printers. Read on to discover how scientific experimentation has established a better answer.
The overall winner is sequence 5, MYCK (Table 1). This has good general performance with the best color balance. It was often a favorite of experienced judges. Sequence 3, YMCK, was also quite good but always disliked because of its strong moiré in the lily. If the angles for the M and the C were reversed, then this sequence would have been rated up there with sequence 5 by expert judges.
Caza b, KCMY, has a very strong grey-balance shift and lost a lot of points for general-purpose printing. However, the three-color density shift is less pronounced than in sequence 5, yielding quite satisfactory complex shades. The K-first strategy gives optimal shadow performance, which justifies
Caza’s endorsement of this sequence. It also tends to be less prone to 15° moiré because the Y is printed on top of a jumble of other dots, making it less likely for the 15° moiré to appear.
So, do we have an objective choice? Yes and no. We found the CFI incredibly helpful in debating the various merits of the different prints. By having numbers instead of opinions, we found that we could debate the opinions much more sensibly. If we were real printers, then we would probably choose to restrict ourselves to just two sequences, MYCK and KCMY. For any particular job, we would be able to make a quick decision: If there’s a lot of subtle grey, then we’d use MYCK; if a lot of darker complex tones and shadows, then we’d use Caza b.
Arriving at a good answer
As so often with screen printing, when you strip away unnecessary confusions by getting the basic preparation right, it becomes much easier to make sensible decisions. Choosing the right stencil, the right choice of mesh to remove mesh moiré, the right ink density, and agreeing on a standard of truth made our task much simpler. With relatively few objective measurements and with a simple understanding of moiré, we were able to come up with a couple of print sequences that we would use on a routine basis for four-color printing. We hope that you will be able to reach a similar conclusion by carrying out a few objective tests on your own prints.
Author’s note: This article was written with the assistance of professor Steven Abbot and Bill Appleton. Thanks also to Michel Caza and professors John Davison and Long Lin for their advice and practical help. Tricia Church has worked in the electronics and screen-printing industries for the last 25 years, printing a range of inks onto different substrates using various types of screen-printing equipment.
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