tannages

Tannage, or tannages in the plural, is the process by which raw hides and skins are converted into leather through treatment with tanning agents. The aim is to stabilize collagen fibers so the material resists decomposition, water, and heat, while acquiring desirable properties such as flexibility and color. The term tannage can refer to a specific round of treatment or to different tanning methods used in a single tannery.

Historically, tanning began with plant-based tannins extracted from bark, leaves, or fruits. Vegetable tanning remains in use for some types of leather, producing a characteristic color and a firmer, long-lasting material. In the 19th century, chromium(III) tanning was introduced and rapidly expanded, offering faster processing and softer hides. Today, a range of tannages exists, from traditional chrome-tanned leather to chrome-free options and synthetic or aldehyde-tanned varieties, each yielding different performance and environmental profiles.

Typical tannage steps, as part of a broader leather production sequence, include preparing the hides (soaking, hair removal, fleshing, and pickling), applying the tanning agents (the tannage), followed by retanning, dyeing, fatliquoring, and finishing. The chosen tannage influences the leather’s color, texture, strength, and biodegradability, as well as its suitability for specific end uses such as footwear, upholstery, or fashion goods.

Environmental and regulatory considerations accompany modern tannages, with attention to chemical use, waste management, and worker safety. Different regions prioritize various tanning methods to balance performance, cost, and sustainability.