ARTISTS – please help

When bottling your own ink/paint, you need to put something in there so the ink doesn’t harden. Something that moves the ink around when you shake the bottle.

What do you use?

I’ve used stainless steel ball bearings for years now, but I’m having trouble with a certain brand of ink. It’s white, and the balls are rusting when they never have before.

Should I look into using glass marbles? I need something that won’t clog the hole and can be autoclaved or will come pre-sterilized.