Randy’s Black Label cleaner is the best glass cleaner on the market. It’s formula is a lightning fast resin and goo cleaning solution that can be used for any metal, glass, or ceramic smoking utensil. Just apply the cleaner to any piece, shake, and let it soak for a few minutes before rinsing out in warm water.
I only used this once on some pretty nasty glass. This worked extremely well, but I am very smell sensitive, and the strong smell was overwhelming. A little more intense than ISO, most people would be fine.