A technique in which salt or a salt solution is used to abrade the skin, for example to remove the pigment from a tattoo or permanent makeup.
A good analogy is to think about using sand paper to sand away at the skin until the layers are scraped off. It basically involves scrubbing your skin raw using granules of table salt.
A rotary like tool may also be used to more effectively peel away the skin and pigments. Basically, the area is rubbed until it is raw and it will certainly require bandaging afterward.