I soak my glass bits in Everclear Grain alcohol for 48 hours. Then I pour that gorgeous brown liquid back into an air tight jar. After several different soaks of various pieces, I'll pour the everclear into a glass pie plate and put it on top of my 5.1 surround receiver to evaporate for several days. Take a razor blade and scrape up the leftovers
Note the grain alcohol does leave your glass sticky with sugars. So I use a jar of ISO to give my glass a quick dip before I dry it off.