Choosing the right media for your sandblasting is important and really depends on the job you are doing.
If you aren’t sure whether you should be using a fine or coarse medium, you should test the finder one first and adjust from there.
The reason for this is because the coarse media may well damage the surface when blasted under high pressures.
An example of a finer media would be baking soda or crushed walnut shells, while coarse mediums would be crushed glass and swimming pool filter sand.