Do you need a waterproof tag, and what does the rating cover?
The rating covers the enclosure as tested, not the adhesive holding it on and not the edges once it is applied. Water rarely stops a tag reading, because the field passes through it. What water destroys is the substrate, and that is what a rating protects.
Water does not block reading
The field couples through water with some attenuation, so a wet tag generally still reads. A tag submerged in a glass of water reads at a shorter distance rather than not at all.
What water does is destroy the tag as an object. Paper swells and delaminates, adhesive releases, and the antenna is left free to crease. The tag then fails mechanically, and the diagnosis looks electronic.
So the reason to buy a sealed tag is durability, not signal. That distinction changes what you should be asking a supplier.
Reading the protection code
Ingress protection is expressed as a two digit code defined in IEC 60529. The first digit describes protection against solid objects and dust, the second against water.
The water digit is a ladder, not a scale of goodness. Higher numbers describe different tests rather than strictly better protection: resistance to jets and resistance to immersion are separate conditions, and a product rated for one is not automatically rated for the other.
Immersion ratings state a depth and a duration used during the test. Continuous immersion in service is a stronger requirement than the temporary immersion most ratings describe.
High pressure and high temperature washdown is its own case and is not covered by ordinary immersion ratings.
What the rating does not cover
The adhesive. A sealed tag stuck on with an adhesive that releases in the wet has failed just as completely, and the rating says nothing about it.
The edges after application. A tag trimmed, punched or damaged during installation is no longer the tested article.
Chemicals. Water resistance is not resistance to solvents, cleaning agents or fuel, and a washdown area involves all three.
Time. Ratings describe a test, not a service life. Ultraviolet exposure and thermal cycling degrade seals over months in ways a short test does not capture.
Deciding whether you need one
Ask what the tag will actually meet. Occasional rain on a vertical surface is mild. Standing water, condensation every night, or a cleaning jet twice a day are not.
Condensation deserves particular attention because it is invisible in a specification and relentless in practice. An unheated space cycles through dew daily.
Where the exposure is real, a fully encapsulated tag costs less than replacing a deployment, and it removes the edge sealing problem that laminating a cheap tag never quite solves.
Then age a sample in the real place for a month before ordering. It is the cheapest test available and it settles the question a rating cannot.
Frequently asked questions
Will my tag read underwater?
Usually yes, at a reduced distance, since water attenuates the field rather than blocking it. Surviving the water is the harder part.
Is IP68 always better than IP67?
It describes a more demanding immersion test, and neither covers high pressure jets. Match the rating to the actual exposure rather than reading the digits as a ranking.
Does laminating make a tag waterproof?
It helps and it rarely seals the edges, which is where moisture enters. A purpose built encapsulated tag is more reliable and often cheaper than the labour.
Do I need a rating for outdoor use?
Sun, temperature cycling and adhesive matter as much as water outdoors. A water rating alone does not describe outdoor survival.