We apply it with a dense, soft foam applicator. But that is only part of the process, before this the paintwork needs to be prepared. A soap is used to clean the paint and remove any old wax, a clay bar is used to remove any contaminates, and then the paintwork is wiped down with a solvent as if we were going to repaint the car. Then begins the machine polishing and paintwork correction, where we polish the car to a high shine before wiping it down with alcohol again. Only then do we apply the ceramic coating, carefully, with great diligence.
There is a procedure to do each kind of application, it needs to be done in a controlled environment, not too hot, not too cold, no wind, no moisture, and there is a window of time between putting the coating on and taking it off which can't be missed. If the procedure isn't followed exactly, things can go wrong. Thankfully, we are well practised and things seldom do.