That said, I don't clean my cartomizers anymore. I did try at the beginning, but they are never the same afterwards. I love a fresh carto. They are disposable, after all, and were not designed to be cleaned, washed, boiled and dried... That's just my opinion... A good carto is only capable of processing anywhere from 6 to 10 ml of ejuice, a little more or less depending on the
juice used. Dark, sweet, thick juices gunk up the coil and the filler much faster than the clear ones do. YMMV.
If you want to refresh a carto, vape a tankful of unflavored or 100% PG or VG or mix--that will help dissolve some of the gunk accumulated on the coil, but really, just toss them when the draw gets tight and the flavor and vapor production begin to diminish.