Leather is a natural polymer product rich in collagen. Typically, wet blue leather contains about 60–70% moisture, along with carbon compounds, oils, minerals, and other substances, creating an ideal nutrient source for mold growth. A wide variety of mold spores exist in the external environment, such as air, water, and raw hides. When these spores land on the leather surface, they can thrive under favorable conditions by breaking down chemical components within the leather and rapidly proliferating, leading to mildew. Various factors, such as the leather type, origin of the hides, processing environment, storage location, and storage duration, can significantly influence the types of mold presenting, the rate of growth, and the extent of mildew damage. Most molds found on leather include Aspergillus niger, Aspergillus flavus, Penicillium citrinum, Scopulariopsis, and Trichoderma viride. Currently, the most effective and widely used method of mold prevention in the leather industry is the use of fungicides. During the soaking stage of leather processing, raw hides are immersed in water for 48–72 hours. Without intervention, bacteria in the water can proliferate rapidly, potentially causing irreversible damage to both the grain and flesh sides of the hide. In this environment, fungicides are essential to control bacterial growth and protect the leather surface. Henning offers a full range of anti-mildew and antibacterial solutions tailored for the leather industry, effectively protecting leather products from bacterial and fungal damage.