Blowing through them like analog cigs. Carbon build-up on the coil happens in 2 days of heavy use. Once this happens forget it. No way to clean the build-up off. I've used every thing you can think of. The technology needs massive improvment. Been vaping a year and it's so much work. Bought 5 new atty's and down to one in just 5 days, sucking till my eyeballs are in the back of my head to get any vapor. Yes, I took out the bridge and scraped the coil, yadda, yadda, yadda - it's all no use. Can't take it anymore.