When you get to a point where you want to be building your own coils, vape cotton is a very important part of your vape kit. Whereas in traditional coils you’d have ceramic or cotton wicking material already installed, when you’re making your own you need to thread your cotton through your coil wires. It’s there to act as wicking material to absorb your e-liquid which is then in turn heated up by the wires in your coil. There are plenty of different brands and types of cotton to choose from to optimise your vaping experience when working with an RDA or RTA.