Some previous threads on this topic show the unencased baking soda type beads can be very fragile and possibly crumble later on. You may wish to search for them and read them all to see if a resolution to that is available.
Also, not sure if it is the type of thing you are looking for, but there is another technique called scavo, which does some amazing texturing to glass, link is to a free tutorial:
http://www.anndavisstudio.com/scavo.html