This was first published on JimRaffel.com on Nov. 3, 2005. It has been re-purposed for ColorMetrix.
Client: “What should my color bar look like?”
Us: “What is the meaning of life?”
Honestly, the second question might be easier to answer than the first.
The answer to the color bar question can be both simple and complex at the same time. The client who originally asked this question works for a company with a very large consumer products concern. Therefore, they are the ultimate consumer of the print (in other words, they pay for it). Others in the supply chain are pushing for a fairly large color bar to be included on each package. While in principle we agree with measuring as much as you can, we have also assisted customers with almost no space for a color bar and found a way to measure enough to be meaningful.
The interesting trend we have seen in consumer product printing (read: packaging) is toward more informative color bars. Managing libraries of dozens, hundred, or even thousands of spot colors can be almost impossible. However, if one moves toward some form of 6 or 7 color process printing, some pretty amazing economies of scale begin to occur.
The trick is that if you are producing a critical spot color with a build of process inks, those inks and all associated print attributes need to be “spot on.” The best way to control critical press factors like density, dot gain, print contract, etc. is to measure as many color bar patches as possible. See how simple the answer to these complex questions can be?
So, ranked in order of importance, here are the patches we suggest a press color bar.
- Unprinted substrate patch (to zero out substrate when necessary)
- Solid patch for each process (and spot) color (needed for solid ink density (SID))
- 3/Color Grey patches at multiple tone values
- Mid-tone patch for each process color (to gather dot gain (TVI) values)
- Process color over prints (needed to measure trapping efficiency of inks)
- Additional highlight and shadow tone patches of each process color (for a 75% patch to calculate print contrast)
- GATF Star targets or microline targets (used to visually evaluate for press slur and doubling issues)
The items listed above are important and truly necessary, but if space is an issue, start with No. 7 and work backwards removing items until the bar fits. Also, items 3 and 4 could be easily reversed, but having one without the other makes diagnosis of grey balance issues difficult at best. If you do not have room for items 1-3 and quality print is important to you, maybe you should consider redesigning the piece.