Whenever I clean any of my glass pieces I usually use iospropyl alcohol and regular table salt. I like to use a ziploc bag to place the bowl or slide or downstem in, and then ill add enough alcohol to cover what I'm trying to clean. I then dump some salt in the bag with the piece and alcohol maybe a couple table spoons. The next part is usually fun haha hold your piece through the bag and shake the hell out it for like 2 mins. I usually let it chill in the sink for like 30 mins in the solution. Come back, shake a few times and then pull out what you were cleaning and rinse it really good in hot water. At this point u can use some q-tips to get anything else that was left behind. And dry it out