Five thousand flyers. This service is offered on a Tuesday. The code on all five thousand did not work.
The design had passed four people's approval. It had been checked on screen and it scanned like a dream because on screen a code is back-lit and pin-sharp, and only a code that's printed in cyan on textured stock is about as close to a code on screen as you will ever come.
No one read the printed proof.No one read the printed proof. There was a proof. It was placed in an envelope on a desk.
What actually fails, in order of commonality that I've seen them fail:
1. The code is too small
By far the most common cause. Designers size codes to the layout, not the distance that they will be scanned from, and a two centimetre code on a poster printed at two metres won't work, no matter how well it's printed.
Rough Guide: Code should be approximately 1/10th of the distance to be scanned. Read from thirty centimetres, 3 cm of code. Thirty metres of code from three metres. Round up, always.
2. The quiet zone is crowded
Codes should have a blank margin, approximately four modules in width, around all four sides. It is used to identify the boundaries of the code by scanners.
Designers do not like empty space and will put something in it, a line, a title or bevel on a photo. It then reads inconsistently on some phones and not on others — worse than failing outright, no one diagnoses it.
3. Inverted colours
Write code with light colour on dark background. It looks fantastic. It doesn't work with a significant portion of the applications that use scanners, since many still use dark-on-light and don't bother trying the inversion.
Modern cell phone cameras tend to do fine. Older ones don't necessarily, and older phones are far more prevalent among those you would want to contact.
4. Not enough contrast
Related, but distinct. A mid-grey code on a light grey background meets the criteria of dark-on-light, but doesn't offer nearly sufficient separation. This happens on a regular basis with brand colour palettes.
If you can't read text in those two colours when sitting across from a room, the camera can't either.
5. Low-resolution export
A code exported at screen resolution and scaled up in the artwork develops fuzzy edges. The three corner squares are the alignment markers, and fuzzy alignment markers are fatal.
Export at print resolution or, better, as a vector file. Any decent QR code generator online free will offer a high-resolution or SVG download, and using it costs nothing.
6. The URL is too long
Longer data means a denser pattern with smaller modules at the same physical size. Dense patterns demand better print quality and better cameras.
A tracking URL with five parameters can double the density compared to a clean short link. Shorten it before generating, not after.
7. Print bleed and ink spread
Absorbent stock absorbs ink more than the print's width. On a code, the dark and light portions become thicker and thinner respectively, and after a certain point beyond which the scanner cannot separate them.
That's why the code is correct on the computer but not on newsprint, kraft paper or uncoated paper. Size up on Absorbent Materials.
8. Glare from lamination or foil
Gloss lamination, spot UV, and foil all reflect light directly into the camera on the angle that people normally hold their phone.
Tama makes a matte finish of over codes. Always. This is a quick and forgetful fix.
9. Curved or flexible surfaces
Bottles, cans, tubes, and anything that bends. Curvature distorts the grid, and past roughly a certain radius the scanner cannot correct for it.
Place the code on the flattest available panel, keep it modest in size relative to the curve, and test on the actual container rather than a flat proof.
10. Logos placed badly
The error correction built into the format lets you obscure part of the pattern, which is why a small logo in the centre usually works.
Usually. The failure comes from covering too much, or from covering one of the corner alignment markers because it looked balanced there. Never touch the corners, keep coverage modest, and increase the error correction level if the generator offers it.
11. The destination is broken
Sometimes the code scans perfectly and the page does not load. Everyone diagnoses the code and nobody checks the link.
Expired pages, links requiring a login, and destinations that are not mobile-friendly all produce complaints that sound identical to scanning failures. Check the destination on a phone, on mobile data rather than office WiFi, before blaming the pattern.
The test that prevents all of this
One process, 5 minutes, has nearly all of the above.
Print Code at Final Size, Final Material and Final Ink. Not a laser proof for office paper. The actual thing.
Repeat the process 3 times with the same area. Distances and the use of a modern mobile phone. From the oldest phone in the building, which stands behind a desk. Also because 50% of the real scanning will occur at dusk in dim restaurants, dim shops, dim streets.
All three working, you're safe. If either of these is not working, in most cases, size-up and adjust the contrast and you're done.
Leave the source file. Six months down the road someone will want the code to be scaled and regenerated from the original beats found in a JPEG someone sent them in an email thread.
If a code has already failed in print, do not try to repair the artwork. Generate a fresh code at high resolution from a shortened URL, size it up by a third, and print a proof before committing to another run.
The proof step is the whole lesson. Five thousand flyers is an expensive way to learn it.
FAQ
Why don't my QR code work on the print version?
Backlit screens and pixel-perfect. Print adds the elements of ink spread, glare and reduced contrast, making codes larger and higher resolution than screen testing would indicate.
Are logos OK in the center of QR code?
Yes, it is small, it is in the centre and it will not cover the three corner markers. The higher the error correction level, the more tolerance will be provided.
At what resolution should I export a QR code at?
Use vector format if possible. At least 300 DPI full scale, not scaled up from smaller size.
Does colour influence the scanner?
Contrast is more important than colour. It should be darker than the background, and never be light-on-dark, as it will not work on many older scanners.
How much to size a QR code?
Approximate the distance to be scanned by about 1/10 and then round up. Add to a curved, textured or absorbent surface.
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