So you might think: “What’s the Glycerine for?”
The reason why Glycerine is worked into the coil percolator is because Glycerine stays cold for a surprisingly long time after freezing it. That’s why Glycerine coil percolators are often removable! It is intended that you can take the bong apart and put the Glycerine coil into the freezer.
Once it is cold enough, you simply take it out of the freezer. Trust me you have never had anything like this before! It is like as if a coil percolator and an ice catcher had a child that grew up to get a PHD of Thermal Physics. Smoking an icy coil perc feels like menthol cigarettes without the weird mint flavor. It’s refreshing as you can feel it gently sinking into every bronchial tube of your lungs.
Disclaimer: Smoking this percolator is so much fun you will probably turn your back to any other percolator for a while. Of course, you can smoke a Glycerine spiral perc bong even if you didn’t freeze the coil. But you won’t get any of that cooling effect.