How often should you actually reapply a ceramic coating?

How do I check what state the coating is in?

Ceramic coatings are sold with an advertised lifespan, such as three, five or nine years, but that is how long they last in the best case, under ideal conditions. In practice a coating wears down, and faster on some parts of the car than on others. So instead of counting the time since it was applied, wet the car with a hose and look at each panel on its own:

• on a coating in good shape, water forms small, round beads and runs off in a sheet when the car moves or the panel is tilted;
• when the beads go flat and wide and the water clings in patches, the coating is wearing;
• start with the roof, bonnet and boot lid, which get the most sun and rain, and the lower doors and rear bumper, which take the road grit.

What wears it down fastest?

If the paint has lost its shine, that does not mean the coating is finished. Usually it is dirt bonded on top of it (traffic film, iron particles, hard-water spots), which a decontamination wash removes, so judge the coating after that wash. What shortens a coating's life most, roughly in order:

• automatic washes with brushes;
• washing in direct sun or letting the car air-dry;
• bird droppings and tree sap left on the paint;
• strong degreasers and high-pH cleaners;
• parking outside, unshaded, all year.

So when do you reapply?

When the beads flatten on the roof, bonnet and boot lid, book an inspection at a studio rather than a reapplication. At that point, what the car usually needs is a maintenance layer. A full reapplication means removing what is left of the coating and correcting the paint, and doing it too early wastes the coating that is still there and a little of the clear coat. If someone quotes a full reapplication without inspecting the paint, get a second opinion.