Jessica, fiberglass/silica can be dry burned, while cotton cannot. When you vape a lot of
juice the small particles that cannot vaporize get gunked up on the coil and make it dirty. After a while it stops producing as much vapor and the flavor is off so you need to take it apart, clean it with water, dry it with a napkin, then fire it until it glows. Some people only do it in pulses to avoid melting their coil. This will only happen if you have a small coil gauge. I use 32 awg kanthal and I just hold the button down and let the coil glow until the
devices autoshutoff engages. I do this a few times until the crud is burnt off and the wick looks white. After I'm done it performs as if it is a new coil. However, after doing this a few times dry burning is less effective and I need to do a rebuild.
If you tried to dry burn a dry cotton wick it will burst into flames and a nice looking wickless coil will remain.(trust me, I've tried. LOL)
Other alternative wicks include solid ceramic stone(which are used in
tanks), and bamboo, which is similar to cotton.
