F1 Explained: What is flow-vis paint and why is it used during pre-season testing?

Pre-season testing is well underway for the 2024 F1 season, and you might see cars with splashes of bright paint beyond their new liveries. Discover the secret weapon - flow-vis paint - and its crucial role in testing.

The record-breaking F1 season is finally here, and cars are zooming around the Sakhir circuit in Bahrain for testing. But as you witness the sleek machines carve through the track, you'll spot an unusual paint job - splashes of vibrant hues beyond teams' official liveries.

These aren't artistic flourishes though; they hold the key to unlocking performance secrets. This mysterious paint, called flow-vis, plays a crucial role in pre-season testing, offering invaluable insights into a car's aerodynamic performance.

But what exactly is flow-vis and why is it so crucial? Let's find out.

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What is flow-vis and why is it important

Flow-vis, short for flow visualisation, is more than just paint; it's a window into the invisible forces shaping a car's behaviour on the track. This special blend, made of fluorescent powder mixed with paraffin oil, acts as a temporary sensor.

As the car speeds up and takes corners around the circuit, the airflow interacts with the paint, causing it to streak and dry in distinct patterns. These patterns act as a visual map, revealing how air flows over the car's surface and highlighting areas of separation, turbulence, and efficiency.

This information is gold dust for engineers, as it gives them an idea of how the flow interacts with crucial components like the wings, diffuser, and underfloor of the car.

This allows them to make targeted adjustments, be it fine-tuning wing angles, modifying bodywork elements, or experimenting with different configurations.

Engineer Rob Smedley, who previously worked for Ferrari and Williams, explains how flow-vis works:

"You paint it liberally on the car, the car then goes out and as it’s moving up to speed and going through a cornering condition, the paint dries as the light oil evaporates and you end up being able to visualise, very clearly, what sort of flow structures you've got.

"When we then analyse that – we’re usually looking for things like separation, as in where the flow's separating and we’re not getting decent flow structures across the surfaces of the car. That can then tell the aerodynamicists a lot about what's going on upstream of that, and hopefully that helps them to rectify certain problems on the car."

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