When you are designing and printing your bar code labels in house, you have the responsibility of ensuring their quality when they arrive at their final destination. Because there are very few ideal labeling environments and because the control you have over your labeled products in transit might be limited, you need to take what precautionary measures you can to guarantee bar code label quality.

Everything counts when printing bar code labels: the label material, the ribbons, the printer and the software. A proper on-site bar coding system – one where all the elements work together efficiently – can eliminate potential labeling problems right from the start.

Part I: Label Media
Finding the correct labeling system for your application should start with determining the appropriate pressure-sensitive label media, along with any compatible supplies. The key to selecting the right bar code label is knowing exactly what your labels have to endure before arriving at their destination, as well as after. Temperature changes and exposure to outdoor elements can significantly affect your label choice. Even the amount of abrasion the label might experience during shipping can play a role.

Hundreds of different pressure-sensitive label materials can be created by combining various facesheets and adhesives. Your facesheet selection is divided into paper-based materials and film-based materials, while adhesives include standard, rubber-based or more advanced, acrylic-based options.

Standard paper materials are cost-efficient and durable for many general labeling needs, such as shipping labels. The durability of paper materials can be improved by adding special top coatings and film over-laminates during manufacturing. UV varnishes and latex coatings, for example, can improve a paper label's resistance to moisture, sun and wind.

Film-based materials, such as polyethylenes and polypropylenes, are inherently stronger than paper labels and can be manufactured to be even stronger by treating them with varnishes. Applications involving harsh chemicals, extreme outdoor conditions, or UL/CSA recognition demand film-based labels.

Your choice of printer ribbons (if applicable to your print technology) also is critical. Three types of ribbons are compatible with today's thermal-transfer print technology – resin, wax and a wax/resin combination. Resin and wax/resin ribbons most often accompany film label media and produce imprinting with strong abrasion resistance and weatherability. Wax ribbons are more economical than resins and are ideal for imprinting on paper label media, but with lower abrasion resistance than resins, the application must be considered.

By tracking the path of your labels and being aware of all aspects involved with your application, you can work with your labeling vendor to have the appropriate label media custom manufactured with the correct facesheet and adhesive combination. Your vendor can then advise you on your ribbon options.

Part II: Bar Code Labeling Equipment
Having the right equipment to print your bar codes and variable information is equally important as having the proper labels to print them on. Depending upon your application, thermal-transfer, direct-thermal and laser printing technologies all offer their own advantages and disadvantages.

Thermal-transfer printers produce excellent results, even in less-than-ideal conditions. This popular print technology allows users to match label facesheets and ribbons to optimize their print quality. Single-pass ribbons used with these printers produce a quality image that won't fade or smudge. Additionally, their square matrix printing capabilities provide excellent bar code edge definition.

Most thermal-transfer printers today offer direct-thermal printing modes as well, which rely on specially-coated, heat-sensitive material, not a ribbon, to produce an image. Because the special label material is more susceptible to image-durability concerns, direct-thermal printing has traditionally been a high-quality labeling alternative for short-term applications, such as labeling in grocery store delis or closed systems or for printing receipts.

Designed for industrial use, on-site thermal-transfer and direct-thermal printers are versatile enough to accommodate a variety of label sizes. Models range from economical to high-performance and typically offer 200 or 300 dpi resolution at efficient throughput rates. Additionally, these print engines are often integrated into automatic, in-line print/apply labeling systems for operations requiring the high-speed, simultaneous printing and application of labels to products or cartons coming down a conveyor.

Bar code laser printers also produce high-quality labels but at much lower duty cycles. They are especially cost-effective in some lower-volume applications and can be used for document processing as well.

When examining printing technologies for your bar code labels, keep in mind that the print quality of the bar codes themselves is of foremost importance. Issues such as ink spread, ink voids and specks, ink smearing, uniformity of ink, bar/space width tolerance and edge roughness guide the decision.

Additionally, if you intend on printing non-linear bar codes (e.g. two-dimensional, matrix or stacked), be sure the printer you select can print the symbology you need.

Part III: Labeling Software
The labeling software package you select to format your labels provides you with another level of quality assurance. The market offers a great number of options, and many software packages provide built-in specifications and ready-to-use formats for all popular linear and two-dimensional bar code symbologies and label specifications. Be wary of non-labeling application software that claims bar code labeling capability. Some packages convert bar codes or treat them as graphics. In either case, the bar codes can end up unreadable, or worse yet, cause a misread.

Issues to consider when evaluating various packages include specific printer drivers for bar code labeling printers, editing features, data base capabilities and flexibility in printing options. Further, consider the level of connectivity needed currently and in the future, such as ODBC and DDE.

Part IV: Bar Code Verification
Before shipping your bar code labels, one last crucial step is bar code verification. The best way to guarantee bar code quality is to make sure that you are printing the best possible bar codes from the start.

Both portable and on-line verification equipment is available to help ensure that your labeling system consistently produces high-quality bar codes. These devices test bar codes to determine traditional print quality, wide-to-narrow ratio, print contrast and reflectance parameters, plus they decode and verify character formats. Advanced models help ensure bar code compliance labels meet ANSI X3.182 print quality standards and other industrial specifications, such as Serial 128, AIAG, EAN 128, HIBCC and LOGMARS.

Hand-held verifiers are lightweight and compact, which make them convenient for on-the-spot testing. On-line verifiers, which attach to the front of thermal-transfer printers, read bar codes as they are being printed. If an out-of-spec bar code is sensed, some models will stop the printer automatically.

But on-site verification requires more than just verification equipment. It must include a comprehensive program that adheres to the strict guidelines concerning the verification procedure, where operators are trained and educated and bar code printing equipment is cleaned and maintained on a regular basis.

Consider It All
No matter how simple or complex your bar code labeling application is, every element of your system must be considered. Before any decisions can be made, the details of the specific application must be examined. By taking these precautionary measures in the beginning, you are doing what you can to help ensure that your labels reach their destination the way you intended them to.