Rinse a clean panel and watch the water. Tight beads that roll off means the coating is healthy. Flat sheeting that clings means the hydrophobic top layer has worn. Water lying in patches means it is genuinely spent.
The important nuance: beading fades before protection does. A coating that has stopped beading is often still doing its chemical job on the paint underneath. Losing the beading is a signal to top up, not proof the coating is gone.
Do this test on a properly washed panel. A dirty car will not bead however good the coating is, and that fools people into re-coating early.
This is the step everybody skips and it invalidates the whole test. Road film, traffic grime and old wax residue all sit on top of a coating and stop water beading on it. A dirty coated car behaves exactly like an uncoated one.
Bonnet or roof. Flat panels tell you the most because water has to actively bead rather than just run downhill.
Tight, tall beads that roll off at the slightest angle means the coating is in good shape. Wider, flatter beads that need encouragement means the top layer is wearing. Water that spreads into a sheet and clings means it is worn through.
Bonnet, roof and boot lid take the most UV, rain and bird droppings, so they wear first. If the roof has stopped beading and the doors have not, that is normal wear rather than failure.
A healthy coating feels slick. A worn one feels like bare paint, and a contaminated one feels gritty. Gritty means it needs decontaminating, not replacing — see the rough paint guide.
Etched spots on a coated car usually mean the mineral got past a worn area. That is a stronger signal than beading alone.
| What the water does | Where the coating is | What to do |
|---|---|---|
| Tight beads, rolls off easily | Healthy | Nothing. Keep washing it properly. |
| Beads, but lazier than it was | Top layer starting to wear | A top-up spray. This is normal and expected within the first year or two. |
| Sheets flat, clings to the panel | Hydrophobics gone, base likely still working | Top-up. Re-test after a proper wash before assuming worse. |
| Water lies in patches, some areas bead and some do not | Genuinely uneven wear | Assess in person. Often a decontamination and top-up rather than a re-coat. |
| No beading anywhere plus new water spot etching | Spent | Time to re-coat. That means stripping what is left and starting from decontamination. |
| Paint feels gritty | Contaminated, not necessarily worn | Decontaminate first, then re-test. This one catches a lot of people out. |
Almost every car people bring us as "the coating has failed" turns out to be a dirty or contaminated coating rather than a dead one. Wash and decontaminate before spending on a re-coat.
The manufacturers publish durability figures for their products, and it is worth knowing which one is on your car before judging it.
Gyeon Q² CanCoat EVO, the 12-Month Sealant tier, is rated by Gyeon at up to 12 months on a daily driver. Expect the beading to soften well before that.
Gtechniq EXO v5, the 2-Year Sealant tier, is rated at 18 to 24 months and is the most aggressively hydrophobic of the three on day one — which also means the change is more noticeable as it wears.
Gtechniq Crystal Serum Light, the 5-Year tier, is rated at up to 5 years. On CSL specifically, the base coating routinely outlasts the beading by a long way, which is exactly why a top-up rather than a re-coat is usually the right answer.
5-Year Plus is CSL with an EXO v5 top coat. The EXO is the sacrificial layer by design — when the beading fades, you refresh the topper, not the base.
Those are manufacturer ratings under good care, not promises. San Francisco pulls all of them down: salt air, constant fog wetting and street parking under trees. And to be clear about what we do and do not offer — SF City Wash is not a Gtechniq Accredited Detailer, so there is no warranty on any of these tiers. Gtechniq only honours its Crystal Serum Light guarantee on accredited installs, and we are not going to imply cover we cannot provide.
A top-up is a fraction of the cost of a re-coat, and it is the right answer far more often than the industry admits. A re-coat means stripping what is left and starting from decontamination, which is close to the original job.
Send a photo of a rinsed panel with the water still on it. That single photo answers most of this page for your specific car.
More short answers live on the FAQ.
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That is the whole test. Send us the photo and we will tell you top-up or re-coat.