I soak in oxygen clean over night then hit them with a mr. clean magic eraser.
Follow that up with micro mesh pads, and finish with a quick buff using a microfibre rag.
They come out looking like new, iv'e done probably 25 pipes using that method.
Is it possible to darken vulcanite that has already lightened from oxidization? A friend gifted me a pipe and the vulcanite is very light colored. I applied some Obsidian but it hasn't really darkened.
I scrub mine with a shotgun patch soaked in acetone, let it dry for a few hours, then I give it a good coat of Pensbury Manor Pen Potion #9, which was designed for vulcanite fountain pen bodies but works a treat on pipe stems.