Barcodes are forgiving of a wide range of inaccuracies. The experiential evidence alone validates that: how many times in recent memory have you encountered a barcode that did not scan quickly—or at all? Probably few times if at all. The quality control attributes also bear witness to the robustness of barcodes. Most of the print quality parameters are graded; they have a tolerance or range of acceptability within which the barcode should perform. Only a few parameters are pass/fail with no margin of error. Those are the potential barcode killers.
Violated or encroached quiet zones are probably the most common cause of barcode failure. On a 2D symbol like a QR or Data Matrix code, quiet zones are included in the Fixed Pattern Damage parameter.
The quiet zone defines an unobstructed area around the barcode. This helps the scanner to find and identify the barcode. Scanning technology utilizes reflective differences to decipher a barcode, so extraneous reflective differences, in the form of text or graphics, can confuse the scanner.
Print gain is another common cause of barcode failure. This is the result of ink spreading during the printing process. There are many potential causes:
- Physical pressure exerted on the printing plate against the substrate
- A porous substrate that the ink wicks into
- Surface tension when two or more inks come into contact with each other
- Failure to compensate the printing plate or design file (bar-width reduction)
Printers are generally aware of the causes of print gain, but there are situations that contribute to unclarity about bar width reduction. Driven by a desire for data control and security, some companies provide the barcode design file to their printer-contractors. All print processes need consider print gain, and most of them will require some level of bar width reduction. Determining the amount requires some testing as well as some process control. Without this, the printer must use uncompensated or incorrectly compensated files to produce working barcodes. When they cannot, the customer often fails to understand that their own practices have created this untenable situation for their vendor.
There are other factors that can kill otherwise high quality barcodes. These are the most common. What have you experienced with bad barcodes? We would love to hear your stories. You are welcome to comment here.
John helps companies resolve current barcode problems and avoid future barcode problems to stabilize and secure their supply chain and strengthen their trading partner relationships.