What does Acid Wash mean?

Also known as Marble, Moon Wash, and Snow Wash, this finish gives indigo jeans sharp contrasts.  It is done by soaking pumice stones in chlorine and bringing into contact with raw indigo denim.

Heddels explains Acid Wash

After raw denim undergoes an acid wash (prior to being sold on market), it has achieved high contrast fades.  Since one of the main goals of wearing raw denim are the resulting fades and acid washing bypasses that process, this could be seen a benefit to some.

However, it is arguably not advantageous.  Among many reasons, genuine denim fades are personal to one’s body and pre-made fades (via acid wash) do not exactly match to any one person.

Additional Resources

Example of acid washed denim: