How do you tag a printed poster?
The paper is never the problem, since print and paper are transparent to the field. What decides the outcome is the wall behind the poster, the height it hangs at, and whether anything on the poster tells a passer by that a tag is there.
What is behind the poster
A tag on the back of a poster is a tag on whatever the poster is mounted to.
Foil backed board, a metal frame, a lift interior, a display case: all common poster locations and all conductive.
The same poster works on a plaster wall and fails on the panel next to it, which produces the impression of unreliable tags rather than a mounting problem.
Where the mounting is metal, an on metal tag applied to the front of the poster is the practical answer, accepting that it is visible.
Height and reach
Posters are hung to be read, which is eye level and above. Tags are used at hand height.
A tag at the top of a poster is a tag most people cannot comfortably reach, and one nobody will reach with a queue behind them.
Put it low, roughly where a hand falls naturally, and let the poster do the announcing higher up.
Check reach for the shortest likely user rather than for the person installing it, who is usually standing on something.
Nothing announces it
A tag behind paper is completely invisible. A poster with a chip and no marking is a poster nobody taps.
Print a target at the tag position, with a few words saying what happens and what the person gets.
Use the word hold rather than scan, since scan sends people looking for a camera and a code.
And include a printed address, which serves everyone whose phone will not tap and costs a line of type.
Posters are temporary
A poster is replaced at the end of a campaign, and the tag goes in the bin with it.
So the tag is a per campaign cost rather than an installed asset, which changes the arithmetic against a printed code considerably.
Where the site is permanent and the artwork changes, a tag mounted on the frame rather than the poster survives the change and can be redirected.
That arrangement is usually better: one durable tag per site, a stable address, and new artwork that points at the same place.
Frequently asked questions
Does printing ink block the tag?
Ordinary inks do not. Metallic inks and foils can, so a design using them over the tag area deserves a sample test.
Where should the tag go on the poster?
At hand height rather than at the top, with a printed target marking it. A tag people cannot reach is a tag nobody uses.
Can I put the tag behind the paper?
Yes, if the mounting behind it is not metal. On a metal frame or foil backed board an on metal tag on the front is the practical answer.
Should the tag be replaced with the poster?
Not if the site is permanent. A tag on the frame with a stable address survives every artwork change and costs less over time.