The researchers monitored the temperature just below the surface of the potatoes, where the crust of the chip forms, and also examined the thickness and profile of the crust under the microscope. Convection currents are created both within the pan as a whole and from the rising of bubbles that grow on the potato surface as the oil being to boil. As the g-force rises, these bubbles become smaller and more numerous and they rise faster. However, when it reaches 3g, the bubbles are so small that they get stuck to the potato by capillary forces, and so further increases in gravity make little difference.