answer:That’s usually done by flame polishing, but that would be hard to do with your current setup (it requires better temperature control than you have with your little kiln, or an oxy-fuel torch). Abrasive polishing would be a huge amount of work, requiring you to work through many successive grades of abrasive. You really don’t want to go there. Another possibility is to spray it with a special flux made for this purpose (see “Black Magic” on this site . This causes the surface of the glass to melt at a lower temperature, so you don’t have to refire to such a high temperature. Not real cheap, though :(