I use a mandrel and carbide grit to clean bead release from all beads.
I do not use a diamond drill bit.
I find that a diamond drill bit can chip the glass around the bead hole.
My long beads are focals that can take a couple hours to make.
I do not want to risk chipping anything.
Using silicon carbide grit (100-200 grit) is an especially effective cleaning method on long beads.
Do this over a pan or bowl of water. Not over the sink!
-Use the same size mandrel that the bead was originally made with.
-Immerse the bead in the bowl of water and lift it out. It needs to be wet.
-Dip the mandrel tip in water and then into the silicone carbide grit. This will gather some grit on the mandrel.
-Plunge the gritty mandrel in and out of the bead hole several times.
The grit and friction of the mandrel easily scrub away the bead release.
You will see the bead release turn to a grey slurry that can be rinsed away.
-Dip (rinse) the bead in the bowl of water and check the bead hole.
Repeat the grit cleaning process two or three times if needed.
-When finished, wait 10 minutes and allow the grit to settle in the bottom of the bowl of water.
-Carefully pour the clear water from the top surface and then pour/dispose the grit into a paper cup filled with paper towels or some other place. DO NOT POUR THE GRIT DOWN THE SINK DRAIN!!!!!
Lapidary shops carry the silicon carbide grit.
Here is a source I have used in the US where I can order and have it shipped.
There are lapidary shops all over the world.
https://www.rockshed.com/rock-shop/r...-carbide-grit/