Some of the specialist globe-suppliers carry a product called "Globe Dip", also known as "Colour Dip", or simply "Dip".
I find the suppliers of globes for "lighting/entertainment industries" have the dip, whereas your typical decorative lighting store won't carry it.
I'm sure a bunch of Art & craft places would carry something very silimar, as there's so many glass-craft things out there.
MM.
