In-Spec Satisfaction

Tips for printing high-quality UPC and Code 128 symbols.

Courtesy of Weber Marking Systems, Inc.

If you are required to comply with the bar code labeling specifications of one or more of the major retailers, you are probably quite familiar with the two prevailing symbologies used in that market – the Universal Product Code (UPC) and Code 128, which is used in UCC Serialized Shipping Container labels.

Actually, familiar might be an understatement. You probably know these basic retail compliance elements like the back of your hand. But are you aware of the potential pitfalls that can occur when printing these two symbologies? They are not always visible to the naked eye, but they can result in costly charge-backs for out-of-spec readings.

This article will introduce you to these pitfalls and offer you reliable methods of preventing such disasters.

The dangers of marketing to UPC

As the most recognized bar code symbology, the UPC code is used at the retail level to identify single products on a store shelf.

Because the bar code is being placed on the primary package, marketing influence carries a lot of weight. They can't avoid having a UPC code, so marketers want the symbol to be as unobtrusive to the product's image as possible. The measures taken to comply with marketing desires can have a detrimental impact on the compliance demands of retail customers.

For example, U.P.C. bar codes are frequently printed too short, an ailment known as truncation. (See above.) When a symbol is not tall enough, its repeatability, or scannable area, is reduced. This can increase the chances of a misread or a no-read when the symbol is scanned at the point of purchase.
Also consider that U.P.C. and Code 128 symbologies have multiple size elements that require a printer with a high enough density to meet the tolerance requirements. Using a printer that was specifically designed for bar code printing can produce no-reads or misreads, as well.

A U.P.C. code that is improperly printed also runs the risk of not having a large enough quiet zone, the vacant areas before and after the code. For a U.P.C. bar code to scan properly on the first try, the quiet zone on each side must be a minimum of nine times the width of the narrowest bar. (See below.)
Some marketing demands may require U.P.C. symbols to be printed in colors other than black. Extreme care must be taken and extensive testing done to ensure that scanners can read the bar code. Bar codes printed in red or pastels should be avoided.

As a final note about U.P.C. codes, print quality must be in-spec. There are a variety of reasons why retailers use bar codes at the point of sale, including price accuracy, automated replenishment, and fast checkout. Out-of-spec bar codes jeopardize all of these, but print quality can be deceiving; what appears to be a good code may result in a bad scan. The human eye sees bar codes very differently than a scanner does.

Generally, Code 128 can be printed with fewer risks. Because the symbology is used in a shipping label format that is applied to the outside of a carton or pallet, marketing considerations are not significant. These codes are usually printed larger, with generous space for quiet zones. Print quality, however, still needs to be monitored.

Another factor to be considered when printing Code 128 is the symbol’s unique check-digit configuration. Code 128 incorporates two check digits, while U.P.C. has only one. In both cases, the check digits are calculated from the data characters in the bar code. These extra characters ensure accurate scanning and are used by the scanner/decoder to verify the encoded data. Most thermal/thermal-transfer printers automatically calculate check digits. The right software package can do so, as well. Again, be certain the hardware and software you purchase can handle printing within specification.

The key to printing in-spec bar codes the first time, and every time, is to use the proper equipment, specifically the correct design software and printer combination, with a solid verification system.

In-Spec Inspection

Bar codes can be printed on almost any type of printer. In-spec bar codes cannot. Using a printer specifically manufactured for the strict parameters of bar code printing can prevent errors in format and print quality. Regardless of the print technology chosen, the combination of print technique, label stock, and imprint supplies (such as ribbons and toner) is vital to printing quality bar codes.

The right label design software package is as equally important as hardware and supplies. The market offers a lot of options. Many of them provide built-in specifications and ready-to-use formats for all popular bar code symbologies and label specifications.

By taking these precautionary measures when designing and printing your bar codes, you have already greatly reduced your chances of producing an out-of-spec bar code label. However, for 100 percent accuracy, an appropriate verification system is a must. Verifiers are available in portable, handheld units, as well as in stationary, on-line systems that attach to the front of thermal-transfer printers and verify bar codes as they are being printed.

If you purchase preprinted labels, verification may not be your responsibility. But a bad read at the customer’s site is, so you have to make sure that your supplier is taking verification measures, as well.
If you think you are saving money by creating a bar code labeling system from an existing word processing or graphics setup, think again. Purchasing a new label printer, a compatible label design software package, and a verifier could cost less than one rejected order from a retail customer.


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