High temperature evaporant for glass

I'm looking for material, which I can use for glass cutting/polishing process. The problem is: after polishing of polycapillary, its pores (channels) became blocked by glass dust. I'm planning to fill channels with some material to prevent its blocking and remove this material after machining. But ID of capillaries too small (5-20 microns). I suggest that I have to use high evaporative at high temperature (>100C) material to get clean inner channel surface after evaporation process. Does anybode know suitable non-toxic filling material? I've search all-over the web, but still cannot find anything.