Talc, baking soda, chipped steel, carbon slag, etc.
If it'll fit through a nozzle you can blast with it. How it works depends on how abrasive it is and how durable a medium it is.
BTW Lance Caswell is great to deal with!
You have to be careful here. I see talc mentioned, may not be such a good idea. Some talc has corn starch or corn meal, (well corn something anyway), and is VERY flamable. There was an incident some years ago with Burt Reynolds where he had a minor explosion/flash flame while with talc. This was when he was a new dad, and he was very concerned about "had he been changing the baby. It made the news, there were demo, most impressive demos.
Glass works real well, and you can leave the aluminum and other parts just as is and they look great. Also cleans out real well. Is your compressor running on 220? Less chance it will blow a circuit if it is. Plus, it will cost less to run. The way an electric meter works is it measures which ever leg is drawing more, and then doubles it. So if your compressor is running on 110, you will actually pay as much as double to run it. I balanced out the legs at my house and reduced my electric bill by around $35 a month! Just by switching circuits from one side to the other.
Tom