Common barcoding issues and how to avoid them.

Good advice from Cobalt

Good practices and adhering to the generic barcode printing guidelines will alleviate most of the issues that can occur. Below are illustrations of some of the issues that you might encounter and some advice on how to prevent them.



  • 1

Barcode will not scan

    Issues   Advice

Barcodes that have been printed using incorrect colour combinations, often red bars on a pale background, or reversed images where the bars are white against a coloured background, will not scan.

Traditional barcode readers use red light, and of course are looking for contrast. Black or Blue on red will stand out to the reader, however red or yellow for example will not stand out.


You can test if the barcode will be readable by looking at the code through a red lens.

Use ISO/IEC 15426-1 Compliant Verifiers.


White Lines or Missing Bars

    Issues   Advice

Printhead failure will leave white lines through the print in the direction of feed.

Printheads will fail faster when printing in ladder format as per this image.

Element failure when printing in picket fence can change the code characteristics.



When white lines like this appear the printhead must be replaced.

Always print codes in picket fence. Codes will be sharper and printheads last longer.

Bearer bars should be added to top and bottom of the code. When white lines appear in these, replace printhead.


Barcodes are too small or too large

    Issues   Advice

Barcodes can be missed by fixed readers in automated systems if they are too small.

Some readers won’t read at all if the code is too condensed.

Ensure the bars are at least 32mm in height plus the bearer bars.

Use a minimum barcode magnification of 50% for labels printed using thermal transfer.


Labels are Peeling

    Issues   Advice

Peeling is usually caused by extreme heat which dries out the adhesive, degrading labels due to age, or wrong adhesive for the application.


Get a clear understanding of the label life cycle and what conditions it will be exposed to.

Our media specialists will specify the correct solution based on the above.


Label Creasing

    Issues   Advice

Creased labels cause great difficulties when trying to read them. Creasing is generally caused by human error when hand labelling. Creasing can also be caused by uneven and contaminated surfaces, so you should always check the condition of the surface you're applying to.

Creased labels are common in automatic corner wrap applications.

Look for best consistent area on your packaging to apply labels.

Automated print and apply will give uniform application, improved efficiency and cost savings.

2 Labels on 2 adjacent faces. Better application, better print and more options.


Barcode is printed in the wrong orientation

    Issues   Advice

Printing a barcode in ladder format – the wrong orientation will result in fussy trailing edges on the bars. This makes reading more difficult and will reduce overall grades when checked with a verifier.

Printing barcodes in the wrong orientation can cause excessive wear of printheads.

Barcodes should be printed in a 'picket fence' orientation, not a 'ladder' as shown in the picture to the left.

This assumes the label in the image is printed narrow edge leading.


Barcode printing too close to the edge

    Issues   Advice

Barcode readers must see the whole code to read and decode accurately. Otherwise, the code image will fail to read.


Quiet zones or clear space should be present at each side of the code.

Apply the logic of 10 times the minimum bar width as a minimum for quiet zones.

Avoid applying the code to your product within 19mm of a vertical edge.

If design is OK, but the print is falling off-label, check the printer and media tracking.


Consumer barcodes showing through

    Issues   Advice

In some cases, this simply can’t be avoided.


Configure the readers to read the specific code type you are looking for (GS1-128 for example) and ignore other types.


Need help or advice with a barcoding problem? 
Contact our specialist team today on 01270 539800 or