Which adhesive holds on which surface?
The most underestimated variable in a deployment. A tag that reads perfectly and falls off in three weeks has failed as completely as one that never read at all. Surface energy, texture and application temperature decide the outcome, and the last one is the usual culprit.
Two families of adhesive
Rubber based adhesives grab immediately and hold hard from the first second. They lose that grip with heat, with ultraviolet light and with time, so they suit temporary indoor use.
Acrylic adhesives grab weakly at first and build strength over hours or days. They tolerate heat, cold and sunlight far better, and they are what belongs on anything meant to stay.
The practical trap is that an acrylic tag feels badly stuck when applied, because it is. Judging it in the first minute and peeling it off to try again is how a good bond gets destroyed.
The surfaces that resist
Some plastics resist ordinary adhesives by their nature. Polypropylene and polyethylene, common in crates, bins and packaging, need an adhesive formulated for them and reject standard ones regardless of how carefully they are applied.
Textured and porous surfaces reduce the contact area to whatever touches the high points. Rough concrete, unfinished wood, powder coated metal and fabric all fall here.
Contaminated surfaces defeat everything. Dust, grease, silicone release agents and cleaning residue sit between the adhesive and the substrate, and the bond is to the contaminant.
Curved surfaces add peel stress at the edges, and a rigid tag on a tight curve lifts at the corners no matter what holds the middle.
Application temperature
Every adhesive has a minimum temperature below which it will not wet the surface properly. Apply below it and the tag looks stuck and never bonds, then releases weeks later when nobody connects the two events.
This is the single most common field failure and it is invisible at the moment it happens. Outdoor winter application is where it appears, and it appears whatever adhesive was specified.
Warm the surface, warm the tag, or wait. Applying at room temperature and letting the assembly go cold afterwards is fine, because the constraint is on bonding rather than on service.
Specifying an adhesive
State the surface material by name, not as "metal" or "plastic". Powder coated steel and bare aluminium behave differently, and polypropylene behaves unlike either.
State the temperature range in service and the temperature at application, since they are different requirements and the second is the one that gets forgotten.
State whether removal must be possible. A permanent adhesive that has to come off takes the surface finish with it, and a removable one that has to stay will not.
Then test on the real surface for a week before ordering in quantity. An adhesive that survives seven days on the actual material has told you more than any datasheet.
Frequently asked questions
Can I use my own double sided tape?
You can, and it becomes the weakest part of the assembly. Foam tapes also add thickness between the antenna and the reader, which costs a little range.
Why did my tags fall off after a month?
Most often because they were applied below the adhesive's minimum temperature, or to a contaminated surface. Both look fine on day one.
Does the adhesive affect reading?
Not chemically. Thickness matters slightly, since it holds the antenna further from the reader, and a metal surface underneath matters enormously.
How long before a tag is fully bonded?
Acrylic adhesives build strength over hours to days depending on temperature. Treat the first day as provisional and avoid testing the bond by pulling at it.