Verify the Whole Printing Process

Most people think of verification as something that is done during the on-press part of the printing process. What a shame this sort of thinking is. Consider that there are two major steps in the printing process: pre-press and on-press. Pre-press is the Error Prevention step. On-press is the Error Detection step.

Verify the whole printing process: Pre-press is the error prevention opportunity. On-press is the error detection step

There is a lot of Error Prevention that verification can do in pre-press. Consider the following:

  • Validating the bar code on the package.

The encoded data on the verification report is what is actually embedded in the bar code; this is what the point-of-sale transaction will record and what the inventory will actually replenish. If it’s not what is supposed to be on that package, this is the only time you’ll find out before it becomes a major problem.

  • Testing the Check Digit

Incorrect check digits are not only caused by faulty design software. Ignorant, overzealous graphics techs have been known to manually change bar code human readable data, thinking it somehow also changed the encoded data. Rule of thumb: if something could possible go wrong, at some point it will. Verifying the proof is the only way to find and prevent this devastating error.

Verify the  whole printing process: Bar codes are no longer just bar codes–now structure  is just as important as the scanability

  • Testing Bar Code Structure

Bar codes are no longer just bar codes. They now have industry-specific applications that require them to be structured in certain ways, with certain essential attributes. Recently I was involved in a situation in which a designer created a Code 128 for a major European clothing retailer. Three spaces were embedded at different places in the data string—Code 128 has the ability to encode spaces along with lots of other non-alpha-numeric characters. Spaces don’t necessarily appear in the human-readable interpretation of the bar code. There is now a warehouse full of unusable corrugated packaging with incorrect bar codes and a massive cost implication.

  • Testing Quiet Zones

Quiet Zones have a minimum width but not a maximum width. The most frequent cause of quiet zone failure in corrugated printing is ink spread, not design error. Testing the quiet zones at the pre-press stage can detect if only the minimum amount of spaces has been reserved—and that is the time to correct it.

  • Making sure BWR is present and correct

Bar code design software provides for the user to define their desired bar width reduction but in some of them, entering a negative BWR (a double negative) results in a bar width expansion factor, causing bars to be wider, not narrower.

Error Detection at the on-press stage is pretty much just a reporting function. About all that can be prevented at this point is for bad bar codes from escaping the plant. We have already written much about on-press and post-production verification; please see other blogs to review that information.

Verify the whole printing process to prevent as well as detect a lot of problems

The point here is that verification should encompass the whole printing process. Verification is a tool in the printer’s toolbox that can prevent and detect a lot of problems.

John Nachtrieb

About John Nachtrieb

Mr. Nachtrieb has 30+ years of hands-on experience in barcode technology. His team imaged the film master for the first commercially scanned barcode in North America (1974). His specialty is barcode quality. He created and hosts a highly customized barcode quality seminar which has been presented to 100's of companies, reaching thousands of quality-concerned people, helping them to avoid barcode problems and manage barcode-related risk.

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One Response to Verify the Whole Printing Process

  1. Greg Zimdahl January 24, 2013 at 8:15 am #

    Thanks for the well written article. Barcode verification at pre-press stage is a highly crucial step in the quality control stream. Any of the problems you outlined are painful when you look at them from a financial perspective. However as you state these problems can always be avoided by a skilled pre-press house with a good quality control team. Well written.

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