What does Desizing mean?
A type of enzyme rinse known as desizing that softens denim.
Heddels explains Desizing
Desizing removes the solution added to the fabric during the sizing process. Through the use of desizing agents, the sizing is either degraded or solubilized. Enzymatic desizing, the most popular method of desizing, uses amylase enzymes to eat away at the sizing; however, the process can also be accomplished with an oxidizing agent or sulfuric/hydrochloric acid.