NASA’s bright pink Pressure-Sensitive Paint (PSP) is helping to test new aircraft designs. A thin coat of PSP is sprayed onto the model that will be tested in the wind tunnel and allowed to dry. The model is then installed in the wind tunnel, which also is equipped with a series of blue LED lights and specially equipped black and white cameras to record the test. With the wind tunnel active, air flows over the model, resulting in varying surface pressures.
The blue lights excite molecules within the paint, called luminophores, causing them to fluoresce. At the same time, due to the nature of the paint’s chemistry, oxygen molecules quench the luminophores. High-pressure areas have more oxygen, so the pink shines dimmer. Lower pressure areas have less oxygen, so the pink shines brighter.