A novel approach for analyzing the migration behavior of fatliquors within leather

Abstract Fatliquor migration within the leather matrix may lead to the formation of fatty spew, oil patches and fogging, posing challenges to the production of high-quality leather. Currently, it lacks a straightforward and effective method for analyzing fatliquor migration behavior. This investigation introduces a novel approach for analyzing fatliquor migration by measuring its spreading area on collagen fiber membranes. By applying 300 mg of fatliquor onto 0.5 mm square membranes (10 cm × 10 cm), distinct oil spots were observed, enabling analysis of migration behavior. Using stearic acid as a standard reference compound effectively minimized the influence of different leather sections on fatliquor migration. Fatliquors with low molecular weight, low melting point and high aliphatic ester content exhibited obvious migration potential. Organic-tanned leathers and sulfated fatliquors displayed weak interactions, resulting in easy fatliquor migration within the leather. Conversely, metal-tanned leathers and phosphorylated fatliquors demonstrated strong interactions, effectively hindering migration. This research provides valuable practical and theoretical insights for developing effective strategies to prevent and control fatliquor migration in leather production. Graphical abstract