Tanning

What is tanning?

Tanning is the chemical and mechanical process that transforms raw hide into a stable, durable, and noble material suitable for creating luxury items such as watch straps. Its roots lie in ancient civilizations—Egyptians practiced rudimentary forms of tanning with vegetable tannins extracted from barks—but it reached its most refined form during the European Middle Ages, when artisans from Flanders and northern Italy codified techniques still employed today by master tanners of excellence.

During tanning, the collagen fibers of the raw hide are stabilized using vegetable tannins—extracted from oak, chestnut, and mimosa barks—or metallic salts like chromium (chrome tanning). This process prevents biological decomposition, imparting specific physical properties to the material: controlled elasticity, tensile strength, partial impermeability, and the ability to develop a natural patina over time. The choice of tanning method determines the most distinctive characteristic of a leather: its visual and tactile "character."

Characteristics and Properties of Tanned Leather

Each tanning method produces different results in terms of appearance, feel, and behavior over time:

Vegetable tanning is the preferred choice for Milanese artisans like Milano Straps: it gives a visible texture, a warm feel, and that particular ability to develop a patina—a natural chromatic refinement—that tells the owner's story. Each strap becomes a personal document of wear, warmth, and intimate relationship with the wrist.

The softness of tanned leather depends on both the method and subsequent mechanical processing: the leather is beaten, stretched, and folded to develop elasticity without losing structure. The grain—the small irregularities and reliefs on the surface—is a sign of authenticity in vegetable tanning, an indicator of superior quality raw material that is not industrially standardized.

Use in Watch Straps

Tanned leather is the natural substrate for high-precision artisanal watch straps. In the watchmaking context, specifically:

Stylistic compatibility: Vegetable tanned leather pairs masterfully with classic and vintage watches—Rolex Submariner, Omega Seamaster, Patek Philippe Calatrava, Jaeger-LeCoultre Reverso—creating an aesthetic contrast where the natural patina of the leather balances the robustness of the case metal. Vegetable tanned straps intensify the "vintage watch" character even on modern timepieces.

Proportions and lugs: Milano Straps' vegetable tanned straps are made with lugs (the portion that embraces the watch case) proportioned to the case diameter—straps for 34-36mm require greater delicacy in the grain, while for 42mm and above, the pronounced texture becomes the protagonist. The lugs are finished with hand-smoothed edges, a technique that leverages the fibrous structure of tanned leather to create impeccable surfaces.

Formal-sporty versatility: A vegetable tanned leather with neutral coloring (brown, black, gray) is suitable for both formal and casual contexts, because the natural patina it develops over time is not uniform—the edge of the wrist becomes darker, the inner part maintains lighter tones—creating a visual layering that tells a story of real use, not artificial simulation.

Finishes: The edges of a tanned leather strap are treated with edge paint—a specialized dye applied by hand that protects the cut fibers—or burnished (heated and smoothed) for a superior finish. Milano Straps practices traditional burnishing: the artisan uses a special heated spatula that slightly melts the fibers, sealing the cut without altering the breathability of the leather.

Maintenance and Care of Tanned Leather

Vegetable tanned leather requires conscious, non-invasive attention:

Humidity and water: Tanned leather is hygroscopic—it absorbs moisture from the air. If exposed to rain, immediately remove moisture by dabbing with a dry linen cloth. Do not use direct heat sources (hair dryers, radiators). Allow to air dry naturally, away from direct sunlight.

Routine cleaning: With a slightly damp suede cloth, gently rub the surface to remove dust and sweat marks. Every 3-6 months, apply a minimal infusion of specific natural oil for tanned leathers (jojoba oil or walnut oil)—a massive drop rubbed in slow circles. Do not saturate: the leather must remain "breathable."

Natural patina: This is not a defect, but the added value of vegetable tanning. The appearance of chromatic changes, slight cracks in the folding areas, uneven coloring—these are signs of authentic life. Preserving them means preserving the uniqueness of the strap.

Storage: Store the strap in a dry place, at a controlled temperature (16-21°C ideal). If the strap remains unused for months, wrap it in untreated absorbent paper—never plastic. Plasticization blocks breathability and promotes mold.

Accelerated aging: If you desire a darker patina in a short time, expose the strap to indirect sunlight for short sessions (15-20 minutes a week). UV accelerates the natural oxidation of collagen fibers, intensifying the color without compromising its structure.

Discover Milano Straps vegetable tanned watch straps—pure Milanese craftsmanship, 48h shipping. For a custom strap and personalized consultation, visit the Casati Milano atelier, Via XX Settembre 15, Milan—by appointment. Our master craftsman will analyze your wrist, your style, and your watch to create a strap that becomes an authentic part of your story.