Etching glass I

I like equally the effect of both etched metal and etched glass. But the latter requires use of hydrofluoric acid or equivalents, which is not fun to use at all. It demands a fume cupboard and a professional approach to personal protection equipment.
So I have been experimenting with a potentially safer alternative, namely bifluoride salts. Unfortunately I have not been able to find a supplier of ammonium bifluoride, the salt of choice because of its high solubility in water. Instead I have to make do with sodium bifluoride, which has very limited solubility.
My present interest is in 'bite & grind' which refers to etching a design onto sheet glass, and grinding the design in selected areas with a flat glass pad loaded with diamond abrasive and glycerine as a lubricant. Sometimes one might use 'grind & bite' instead.
Work is going slowly at the moment since this is the middle of the spring term and most of my time is taken up with teaching and administration; and early next week is scheduled as the 'casting days' for two different classes, using silicon bronze, silver and pewter depending on the students' interest.