Finding a scratch on your car is a special kind of heartbreak, but in the future they might be gone before you even notice. Scientists in Korea have developed a coating that self-heals scratches in as little as 30 minutes when exposed to sunlight.

The new coating contains a polymer network based on acryl polyol, with what’s called a hindered urea structure. Essentially, the polymers have dynamic chemical bonds that can break apart in response to a stimulus and then reform in their original arrangement, effectively repairing minor damage like scratches. In this case the trigger is heat, which is provided by an organic photothermal dye that captures infrared light, also embedded in the coating.

In tests on a model car, the team showed that the coating healed scratches in 30 minutes of midday sunlight. In theory, that means someone could key your car door and the scratch could be gone before you come back.

If half an hour is too long, the team also demonstrated that the process can be drastically sped up under concentrated light. Using a magnifying glass to focus sunlight onto the mark patched it up in under 30 seconds.

The team says the new coating has a few advantages over existing self-healing coatings. Using organic photothermal dyes means it needs far less energy to work than regular inorganic versions, which usually require heat guns or concentrated UV lights. Others, like Nissan’s Scratch Shield, work under gentler conditions but can take up to a week. The new coating can also repair a scratch in the same location multiple times, unlike self-healing materials that work using bursting capsules of resin.

Importantly, the new coating is transparent, so it won’t mess with the color of the paint job, and can be applied using existing spray-coating methods. While cars are the primary use case, the team says it could also be applied to other often-scratched devices like phones or building materials.