Why F1 cars have special paint on their cars as 2025 testing begins in Bahrain

The reason why Formula 1 teams spray special paint on their cars during testing sessions has been revealed.

On Wednesday, the 2025 F1 season officially began as testing took place around the Bahrain International Circuit.

The likes of Lewis Hamilton, Liam Lawson, Fernando Alonso, Oscar Piastri and Alexander Albon took to the track in front of the TV cameras for the first time as they put their new cars to the test.

Testing is a crucial part of teams' preparation as it is the first time they can truly see if the work over the winter break has been successful.

During the day, some cars will be spotted with special bright paint as they speed around the track and here is the reason why.

Why do F1 cars have special paint during testing sessions?

Special paint, called flow-vis, is applied on the surface of a specific component to allow aerodynamicists to better visualise the airflow around the car.

The paint is usually applied to the car just before it leaves the garage so that it doesn't dry out too quickly.

With cars hitting incredibly high speeds around the track, the paint, dictated by the airflow, will in turn move across the surface and leave lines on the body.

Ultimately, flow-vis will allow teams to understand the car's aerodynamic behaviour visually instead of just numbers on a computer screen.

It will show the team exactly where the aero is performing well and the areas in which the aero might need to be improved.

Usually, the colour of the paint is bright green-yellow but this will be dependent on the car's livery. In Bahrain on Wednesday, Albon's Williams was seen with red flow-vis paint all over the rear wing while Nico Hulkenberg's Kick Sauber was seen with paint at the front end.

Kick Sauber F1 car seen with red flow-vis in Bahrain testing session. Image: Getty

The application of flow-vis paint is crucial, too much will lead to puddles being formed which means no clear lines will be shown.

However, too little paint means it will virtually be impossible to collect data from the run.

When the car returns to the garage, pictures are usually taken before the paint gets cleaned up.