Common water insoluble powders to use as heatpipe wick.
I'm wanting to make a heatpipe which works against gravity and so am looking for commonly available materials to use as a wick. Like a sugarcube on a spoon soaking up coffee. Except that since I'll probably be using water as my working fluid, the wick will need to be insoluble in water, as well as heat proof to a couple hundred degrees.
A few things I've thought of to try are flour, talcum powder, chalk dust and sand.