retanned

Retanned is a term used in the leather industry to describe leather that has undergone a secondary tanning step after the initial tanning process. This additional treatment is intended to modify properties such as softness, fullness, dye uptake, stability, and resistance to heat and aging, as well as to improve the uniformity of color and surface appearance.

The retanning step involves applying further tanning agents in a finishing bath after the primary tanning. Retannants can be vegetable tannins, synthetic tanning agents (often referred to as syntans), aldehyde-based agents, or mineral tannins. The retanning process is typically performed in one or more baths, with control of parameters such as pH, temperature, and time, and is often combined with subsequent fatliquoring and finishing steps to achieve the desired hand and performance.

Leather described as retanned is commonly used where consistent dye penetration, stability, and a more uniform surface are important. This includes upholstery and automotive interiors, footwear, bags, and various fashion accessories. Retanning can be performed on leather that was initially chrome-tanned or tanned by other methods, and it can be done with chrome-containing or chrome-free agents, depending on regulatory and performance considerations.

In industry practice, retanning is a standard step to tailor the properties of leather to specific end-uses and to meet market expectations for durability, suppleness, and appearance. The term “retanned” refers to the treatment history of the leather rather than a distinct category of finished product.