Do QR Codes Work On Transparent Surfaces? - Feb 2017
A QR Code needs to be made of two contrasting colours. Most commonly you see black and white QR Codes. If the reader cannot clearly detect the difference between the two colours then it's not going to be able to read the QR Code.
For this reason, printing on a transparent surface such as a bag may be unreliable if either the foreground or the background is to be left transparent. If the bag was in front of a dark object when the QR Code was scanned, the black foreground squares of the code would be indistinguishable from the background. You would certainly have better luck if the bag was held in front of a light object.
Guinness is one company who have used this to their advantage. On their pint glass, they have printed a QR Code and when the glass is empty or filled with drink that isn't dark in colour (Guinness), the QR Code cannot easily be decoded. This is intentional so as to provide only those using their product with the QR Code.
Another thing to consider is the material the transparent surface is made from, a glossy plastic bag may cause too much of a reflection for the scanner to focus.
The final thing to consider if using a material that isn't solid such as a bag, is that it's rarely flat and by design will often fold and move, this can distort the print and make a QR code difficult to scan.
If you really wants to get a QR code on a bag that was transparent, think of printing it onto a stiffened label of some sort and attaching that to the bag or make sure that when printed, the foreground and background are both printed and neither are transparent.
If you're new to QR Codes and want to learn a little more, then take the time to read What's A QR Code
Or scan through our FAQs
If you want something a little more technical, try The Technical Stuff