Types of washes for denim come in and out of style. The term "wash" refers to the processing method of that particular type of denim, although the resulting, unique look provides a visual definition for each wash. Unifying elements of modern washes include the use of chemicals and abrasive methods, often employed to create a worn look on the material.
Stone wash denim gained popularity in the 1960s and remain popular to this day. This type of denim is characterized by a lightly distressed, vintage look. The name comes from the fact that the original processing method involved rubbing pumice stones over the denim to wear down the fabric. But that method proved problematic due to environmental concerns over use of pumice and the fact that the stone often weakened the fabric too much, causing too much wear and tear.
A newer stone wash method developed with the help of science. Special enzymes took the place of the pumice stone and work on degrading the material of the denim enough to look vintage but not to the point of destruction.
Acid wash denim soared in popularity during the 1980s before dying out only to re-emerge, as a retro look, in the early 2000s. Despite the name, these splotch-faded denim products didn't get the look from a bath of acid.
Instead, the jeans earned their distinctive look when manufacturers first stripped the denim of its resin finish then applied chlorine to remove the indigo that gives classic denim its traditional blue hue. The result? Denim light in color with white splotches where the chlorine acted more aggressively.
Patented in the late 1980s, garment wash developed as a means of lowering the cost of sturdy denim production. Garment wash jeans have a softer feel than other washes due to the use of warp yarns that are woven and rubbed together.
The garment-wash finishing process involves the application of a phosphate-ester blend that lightly scours the denim. The fabric passes through two washing methods then dries under tension. The finishing process further entails a mechanism called a softener and sandpaper. The resulting product has a distressed look without weakening the fabric.