Whether you work on modern machinery or restore old kit, getting parts squeaky clean before inspection, re-finishing and/or assembly is a key part of the job. For most of us, once parts are degreased the only way to get rid of surface corrosion, paint and other crud is by an application of elbow grease.
This is seldom quick, even less often enjoyable and usually not 100% effective. Compared to handwork, cleaning with the right equipment and material(s) is literally a blast; potentially much more thorough and far more time-efficient. In the widest sense, blast cleaning involves scouring the surface of an item with high-energy particles of material, delivered by a fast-moving column of air or water. It’s a broad church: blast cleaning can happen outdoors, in a dedicated room or in a purpose-built cabinet.