Slamming them with 6volts and keeping them orange for a bit cleans them pretty damn well. Its easy to test after you break the tube on the clear ones and just burn them in the open and watch the coil. Pretty good way to test cleaning methods. The metal ones take 6 volts fine (get kinda hot), but they dont melt down if you take that all the plastic rings out of the top and just dry burn, blow it clean, then reinstall all the grommets.