Pot is legal now in Canada so I thought I'd try taking a photo of how I clean mine out. I wash it first with soap and water and then pour some pure alcohol into it and shake it up to coat the insides. Here I set up dark field lighting using a single strobe with barn doors and a grid to control spill from the backlight. I set things up with a 6 second exposure to capture the flame burning off the gunk on the inside. A little messing about in Lightroom gave me these variations.