First, push out all the excess materials from the glass blunt (as if you were ashing). Then we recommend letting your glass blunt sit and soak in a smokeware cleaning solution or isopropyl alcohol and salt. That will really get your blunt clean.  You can let your glass blunt soak in isopropyl alcohol and coarse salt overnight (give it a couple of good shakes so that salt can scrub out some of the grunge and grime).  There are tons of great cleaners on the market, and some not-so-great ones. Personal opinion, ingredients, and type of residue you are wanting to remove are all factors when selecting the best cleaning solution for your needs.