There is also paint that is poisonous to the barnacles- that's how anti-barnacle paint used to work in the marine industry. But having all of that poison (for

There is also paint that is poisonous to the barnacles- that's how anti-barnacle paint used to work in the marine industry. But having all of that poison (for example, lead was famously used back in the day) was determined to not be good for the our environmental health. Since planes are in a different environment, it's possible that they use paint that is toxic to barnacles (but perhaps is otherwise unsuitable as marine bottom paint).