Ceramic coating: what it does, and what it doesn't

Ceramic coating is a liquid spread over a car's paint that hardens into a very thin, clear layer, much thinner than a sheet of paper. Most products are based on silica (SiO2) or similar compounds.

What does it do?

• Adds gloss and gives the colour more depth.
• Repels water: water beads up and slides off the surface, so dirt sticks less.
• Makes washing easier, saving time and effort.
• Resists chemical contamination such as bird droppings, bug remains and tree sap. These attack the coating first instead of the paint, giving you time to remove them.
• Reduces sun fading of the paint.

What doesn't it do?

• It doesn't make the car scratch-proof. It may reduce fine wash marks, but it won't stop a key scratch or a stone chip.
• It doesn't hide defects. If anything, the extra gloss makes them more visible.
• It doesn't replace washing. The car will still get dirty; it is just easier to clean.

What does "9H" mean?

You will often hear "9H hardness". The number comes from a pencil hardness test: if the hardest pencil (9H) does not scratch the surface, it gets this rating.

But this does not mean the car is now "scratch-proof". 9H on the pencil scale is much less impressive than it sounds compared with other hardness scales. Treat it as a general indicator, not a promise of scratch protection.

Why is the paint polished before coating?

A ceramic coating is a clear layer that locks in whatever is underneath. If it goes on over swirl marks or water spots, those defects stay under it and look even clearer with the added gloss. They can only be fixed later by removing the coating itself.

That is why good shops start with paint correction (polishing), depending on the car's condition, before applying the coating. Ask about this step and whether it is included in the price.

How long does it last?

Usually between 2 and 5 years, depending on the product quality, the number of layers and aftercare. Some products are marketed with longer lifespans. Check the warranty terms and any periodic maintenance they require.