hey i just wanted to chime in a give you some of my info..
ok for one.. consider moving up to a national torch .. they are reasonable priced.. at under a 100 bucks.. and you can now use oxygen and propane.. this will not only increase your speed but its just a much better torch and much better set up.. and its a baby step to a big girls torch.. lol
so the reason your getting the black on your glass.. is......... not all of your gass was buringin up. so it was ending up on your glass.. its like unused gas... imagine if you can the gas is coming out the tank down the hose.. and then hits the torch head where its a flame.. well it has like x amount of seconds to burn up that gas.. this burn will create a suit and what is not burned up will muck up the glass.. the reason i suggest moving up a torch and adding oxygen is the oxygen can help to raise the flame temp.. alot.. and this will burn up the excess gas... also move out in your flame.. the closure you are to the head the more black.. if you move say 8 -10 inches out in the flame this also allows more of the black to burn up before hitting you bead...
also .. if you choose to use your current set up.. then i suggest lowing the pressure on the regulator.. this will reduce the amount of gas coming out and help to get ride of that black...less gas means it has more time to burn up.....
i do know that propane is less likely to do this.. but any gas can have excess... i also know pryex will not have this happen.. i mean its possible i guess but i have never seen it in my almost ten yrs at this.. how ever soft glass always has it.. u really gotta watch your flame wiht soft glass.. it way sensative.. and really requires a lot of practice to not over work your glass and or stain it with soot
well i hope this helps.. u might also try to post this on lampworkect.com i think thats the link.. email me if not.. but there a ton of people over there who are soft glass hot head people.. they can probly help u a lot...
also try wetcanvas.com
they have a glass section..
ok good luck emial if you need my help
thanks annie