Physicochemical, Thermal, and Surface Behavior of Fatliquors and Their Applications in Leather Processing and Sustainability

Fatliquoring is an important step in leather production where fatliquors are added to make leather soft, flexible, and strong. This review focuses on understanding the physicochemical, thermal, and surface behavior of fatliquors and how they affect their performance in leather manufacturing. The viscosity, density, and flow behavior (rheology) play an essential role in how fatliquors work (viz., viscosity and density affect how well fatliquors spread and soak into the leather, while flow behavior determines how easily they can be applied during processing). These behaviors of fatliquors are important because they help to improve leather quality, make it last longer, and ensure the manufacturing process is efficient. Thermal properties, like heat stability and how fatliquors break down over time, influence processing conditions and durability. Surface properties, such as how fatliquors interact with water and adhere to leather fibers, are also key to ensuring good results (i.e., softness and flexibility). Advanced techniques like FTIR, TGA, and SEM have helped to understand better ways. This review also looks at sustainable options for fatliquors such as biobased and eco-friendly alternatives, which can help reduce environmental impacts. This review is important for improving leather quality, making production more efficient, and sustainably protecting the environment.