How Do You Test a Bar Code?

bar-code-verifierWritten by John Nachtrieb  

  Maybe the first question should be, why do you test a bar code — and why is it necessary?

Here's my take. It is necessary to test a bar code because when it doesn’t work right, it causes huge problems and potentially huge liability.

Bar codes hold the retail supply chain together and make it possible to track the movement of food, consumer goods, chemicals, pharmaceuticals, health care products and devices; bar codes are integrated into manufacturing processes, security systems, access control devices, identification systems and myriad other applications.

When bar codes fail, it can be more than inconvenient. It can cost a lot of money, and it can cost lives.

How do you test a bar code?

You test it against several measurable attributes including its reflective and color contrast performance and how accurate it is both in terms of its image integrity and its data structure. Image integrity includes such things as the edge quality and widths of its bars and spaces as well as how precisely bars and spaces are positioned relative to each other.

In order to test a bar code, you need a device that can detect and measure these qualities in the bar code image.

A bar code scanner won't do that—it is designed only to decode the bar code image and extract from it the embedded data.

Scanners from various manufacturers do this in different ways. That means some scanners are more aggressive and tolerant of problems in the bar code image; others are less error-tolerant.

Using a scanner to gauge the accuracy of a bar code is meaningless since no two scanners perform exactly alike. How do you test a bar code with a scanner? You don’t.

How do you test a bar code with a scanner? You don’t.

Scanners cannot test the reflective and contrast properties of the bar code because they are positioned at a predictable distance and angle from the bar code. It is important to test reflectivity and contrast because it is an essential quality in any bar code, and if fails to meet minimum standards, the bar code becomes a liability.

How do you test a bar code? With a verifier.

Only with an ISO-compliant bar code verifier can you test all of the essential attributes of a printed bar code image and grade it in order to predict how that bar code will perform at the intended destination, whether that’s on a nurse’s crash cart in a hospital, making sure the patient is getting the right medications, tracking inventory movement and doing price look-up for a grocery product in a supermarket, or allowing a legitimate employee to enter a secured zone in a restricted area.

How do you test a bar code? Only with a verifier

Only a verifier will tell you when bar code quality is changing over time during the printing operation, and tell you how the bar code quality is degrading and why. This gives you the time and the tools to adjust the printing process, giving your customers confidence in your product and giving you protection against potentially damaging bar code performance liability.

How do you test a bar code? Only with a verifier.

About Barcode-Test

A 30-year veteran of the bar code industry, John Nachtrieb and his company Barcode-Test help provide solutions for customers' bar code quality challenges. He assists product managers, package printers, and suppliers by managing bar code related risk, and supporting bar code integrity over the long haul. You can find more of his writing on bar code quality at the Barcode-Test blog.


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