what is flow vis paint

Flow vis paint is a mixture of oil, usually paraffin, and a fluorescent pigment that is used to visualize the flow of air over a surface. The oil is light and dries quickly, so it is easily carried away with the air stream, while the bright-colored pigment remains on the surface, forming patterns that indicate the direction of the flow. Flow vis paint is applied to the surface of interest, and as the car travels around the track, the airflow pushes the paint around as if it were air, generating visible information. Once the car returns to the garage, the resulting patterns are photographed in detail and meticulously studied for data gathering. Flow vis paint is widely used in Formula 1, particularly during track tests and practice sessions of race weekends, because visualizing the flow patterns close to or at the body surface can provide extremely useful information for improving aerodynamic performance.