If you need to print barcodes on your packages, especially if they need to be scanned at retail checkout, it’s essential that they scan first time, every time.
If your brand is transitioning to 2D barcodes for its retail packaging, it’s likely that you’ll need to print them on your packaging line. To ensure your codes scan correctly, they must meet the GS1 quality standard.
But what does this have to do with shaving?
Well, when a barcode is verified, a number of parameters are measured and assigned a score.
These parameters include: decodability, contrast, modulation, print growth and more. You can see the full list and a brief description of each parameter at the Axicon site.
Barcode shaving, also referred to as pixel shaving or bar width reduction (BWR), is a means to help control the print growth parameter.
Print growth is common when using inkjet printers to print both linear and 2D barcodes. As the barcode image is laid down, each drop of ink tends to spread slightly before it dries on the surface of the packaging material.
In the case of a 2D barcode, such as a QR code or DataMatrix, this causes the black squares that make up the barcode to be larger than the white squares. In extreme cases, the white squares can completely disappear. When the barcode is verified, this can result in a failing grade for the code.
How does barcode (pixel) shaving work?
When your printer is producing barcode elements, such as the lines in a linear barcode or the small squares in a 2D code, that are larger than the specified size, pixel shaving can be employed to reduce the size of the printed elements by eliminating one or more rows or columns of printed pixels around the perimeter.
This results in the printed code element being slightly smaller and the non-printed ones (the spaces in a linear barcode and the white squares in a 2D code) being slightly larger. You can adjust the setting until the balance is correct. The image shows the pixel shaving setting in Loftware barcode software.
What results can you expect?
- Fewer Rejected Prints: Avoid barcode rejects and the costly downtime they cause.
- Higher Line Speeds: When you control print quality, you can run faster without risking unreadable codes.
- Substrate Flexibility: Different packaging materials absorb ink differently. Pixel shaving helps standardize quality across a range of films, cartons, and labels.
- Regulatory Compliance: With GS1 Sunrise 2027 pushing the industry toward more 2D codes like QR and Data Matrix, precision printing will only get more critical.
Best practices for implementing pixel shaving
- Test and Validate: Conduct print tests on your actual substrates under real production conditions.
- Work with Your Printer Vendor: Many modern inkjet printers have built-in pixel shaving settings. Consult with your supplier for optimization tips.
- Mind Your Inks and Materials: Different combinations require different levels of shaving. Water-based inks on absorbent materials may need more aggressive adjustments than UV-cured inks on non-porous films.
- Don’t Overdo It: Too much shaving can cause bars to undergrow, leading to under-thick bars and equally problematic scan failures.
Does this work with every printer?
No, it doesn’t.
Shaving pixels from the barcode elements requires that the symbol is printed with a high-resolution printer, such as a thermal inkjet (TIJ) printer or a high-resolution piezo (PIJ) printhead. TTO printers can also be used with pixel shaving, but the correct matching of substrate and ribbon should make it less necessary for these printers.
The commonly used continuous inkjet (CIJ) printers are usually not suitable for pixel shaving operations, as each barcode element is composed of very few pixels, sometimes just one. CIJ is not the best solution for GS1 2D barcodes in any case
How do I check that my barcodes are of the required quality?
The only way to do this is to invest in a verification system. There are several types of verifiers, from desktop models up to verifiers that can inspect your barcodes on the packaging line at the time of printing.
Axicon and Cognex both make barcode verifiers to help with your quality control processes.
Final thoughts
If your brand expects you to print GS1 2D barcodes as part of the Sunrise 2027 program, it is essential to have a quality control (QC) process in place to ensure every code meets the standard.
Barcode shaving (pixel shaving) is one concept that might help you meet your goals for 100% success!
