QR Codes for Product Packaging

Packaging combines every difficulty at once: small space, curved surfaces, coarse printing and a shopper standing in a badly lit aisle.

Curves

A code wrapped around a bottle or a tin distorts. The rule that works: keep the code inside a flat-enough band, roughly a third of the circumference or less. On a 6 cm diameter jar that is about 6 cm of arc, and a 2 cm code sits comfortably inside it. Beyond that the modules at the edges stretch and the scanner loses the grid.

Print process

• Flexographic printing on film and card spreads ink noticeably. Keep modules at 0.6 mm or above.
• Thermal transfer labels are coarse. Test at production settings, not on the sample printer.
• Direct-to-container printing and laser etching vary hugely — get a physical proof before you commit.
• Shrink sleeves distort as they shrink. The code must be positioned where the shrink ratio is lowest, and the artwork pre-distorted to compensate.

Raise the error correction

Packaging gets scuffed in transit, handled in shops and stored badly. Level Q or H is worth the extra modules here, which in turn means allowing a little more physical space than the 10:1 rule alone suggests.

Materials

Matte film beats gloss under supermarket lighting. Metallic and pearlescent substrates are the worst case — the reflection swamps the camera. If the pack must be metallic, print the code in a matte white panel.

Anything with a long shelf life is an argument for a static code. A product sitting in a warehouse for two years outlives a lot of subscriptions.