Theres lots of other media, including iron particles, glass bead, plastic bead, garnet, walnut shell, alluminium oxide....huge list .....all have their own properties and uses.
Some are single use, some go round and are filtered.
Ye i was thinking about dipping but cant find anybody near me found a guy who does water media and another one near me but i was thinking of doing it myself with soda
my mate got alloy frame shot blasted he then left it his shed for a while you could little specs of rust where shot had embedded into it left a dull an rough finish no good for polishing
i think you need walnut bead or soda blastiing if you intended to polish it