Strap for Portuguese Chronograph Classic Ardoise

The IWC Portugieser IW3904-04 has a lug width of 20mm. This measurement is standard on this model and defines the width of the compatible strap. To verify it, measure the distance between the two spring bars (the lateral pins) with a caliper: it must be exactly 20mm. An undersized strap (18mm) would wobble on the pins, while an oversized one (22mm) would not fit.

The choice depends on intended use and desired aesthetics. For formal elegance: cognac brown alligator or full-grain black calfskin. For vintage-sport matching: NATO strap in gray cotton or alligator in medium brown tones. For everyday versatility: medium brown or hazelnut calfskin with natural patina development. An FKM rubber or black rubber strap is ideal for contexts where durability and water resistance are priorities. Full-grain calfskin remains the most versatile choice because it ages nobly and develops character over time.

The change is a simple operation but requires attention. Obtain a spring bar tool (a tool with a blunt tip) or use the end of a penknife. Insert the tip into the pin hole from the inside of the lug, gently push downward to compress the internal spring and slide the pin outward. Repeat on the other side. The pin will come out easily. Remove the old strap, insert the new one by passing the lug through the pins, then reinsert the pins ensuring they seat fully in their holes. Listen for the 'click' sound: it indicates that the spring has closed correctly.

Yes, any aftermarket strap with a 20mm lug width is perfectly compatible with the IWC Portugieser IW3904-04. Many owners prefer artisanal straps because they offer customization (choice of hides, precise measurements, custom stitching thread) that standard production does not allow. Artisanal straps in alligator, calfskin or natural rubber guarantee superior quality and age with character, transforming the watch over time.

Durability depends on material and use. A well-maintained full-grain calfskin resists 4-6 years of daily use before showing visible wear (cracking, discoloration). Alligator, being a denser skin, reaches 5-7 years. A cotton NATO strap resists 8-10 years or more. FKM rubber lasts 3-5 years before losing elasticity. To extend life, avoid prolonged water immersion (even though the case is water-resistant), clean periodically with a damp cloth, and allow to air dry. Prolonged exposure to sun and chlorine accelerates aging. A well-made natural leather strap, although it wears, develops a patina that many collectors appreciate as part of the watch's history.