Converters use high-tech camera inspection vision systems to control the quality of each individual packaging and to reduce scrap rate. These vision systems check the presence and position of the label on the tub, detect blow-by and make sure the right SKU label is used.
Transparent labels on transparent packaging, or white labels on a white packaging with no print on the critical zones of the label, make it challenging for vision systems to do their job. They have a hard time identifying the real cutting edges of the label, often resulting in false negatives ending up in the scrap bin.
This could be solved by adding visible datamatrix or QR codes to the label design, allowing camera inspection systems to check the label reference. But these take up label space and are impacting the overall look of the artwork. By printing these datamatrix or QR codes in invisible ink, they stay imperceptible under normal light conditions only being revealed when the camera puts special UV-light on them.
Invisible ink
Invisible ink is a specialized ink that is imperceptible under normal light conditions, but is visible under specific UV-light. The transparent ink absorbs the UV-light exposed by the vision inspection system and reflects a specific wavelength so that the camera can see the image. By adding invisible ink all around the borders of the label, one can highlight the cutting edges of the label so that they become visible to the camera inspection systems. The camera can now check the position of the label on the bottom of the cup, the alignment and even blow-by can be detected. A win-win!
