In cruising the watch for a / message boards these last few weeks, there has been more and more discussion on Rolex’s use of stainless steel and the necessity for using a different stainless steel that what is considered industry standard. We had covered this here at Fourtané about a year ago, but thought it might be worth mentioning again because it seems that the Rolex pitted steel question is being asked again by the Rolex wearing community.
Watches requires stainless steel or any material that doesn’t rust for a number of reasons. Because of a Rolex’s proximity to the skin combined with moisture and water make wristwatches a corrosion magnet. In order to keep the watch case waterproof, the threads that hold the crown and the caseback cannot corrode, and the bed that the waterproof rubber gasket rests in also requires a flat uniform surface.
Even though stainless steel is designed to prevent rusting from ocean salt water and sweat, Rolex found excess wear in the caseback threads and watch case from salt water seeping into the threads that sit undisturbed for years between watch services. Salt from sea water or from sweat prove to be catalysts for corrosion and deterioration around the threads that hold the caseback onto the watch case thus making it harder for the rubber gasket to hold a water tight seal.
Noble metal wristwatches such as gold or platinum watches do not have corrosion issues, but base metal does. Until the widespread use of stainless steel, older watches utilized primitive stainless casebacks and some type of base-metal case. Nowadays, most brands utilize 316L stainless steel. Unlike the rest of the industry, Rolex utilizes 904L stainless steel for qualities that Rolex believes surpasses the industry standard.
Rolex calls 904L stainless steel a “corrosion-resistant superalloy.” 904L differs from 316L because of extra Chromium, Molybdenum, Nickel, and Copper that gives it improved resistance to acids. 316L is considered a tougher, harder, “marine grade” steel, but it does not have luster and acid resistance of Rolex’s 904L stainless steel. Rolex aficionados have commented that some people sweat more acidic than others as demonstrated by finding pits in 316L wrist watches making 904L stainless more desirable.
Rolex manufactures 904L under precise quality control. Once received from Rolex steel suppliers, Rolex casts and scans it utilizing an electron microscope that is capable of detecting the slightest structural or surface defect. Rolex has been known to send steel back when it does not meet its exacting specifications or when impurities are discovered. After casting and inspection, the steel is then re-melted in a vacuum to purify it and eliminate any inclusions that would diminish its corrosion resistance and lead to problems in polishing. 904L stainless steel does not machine well which makes it costlier to manufacturer and fabricate into a wrist watch. Subsequently, Rolex designs its own tools to fabricate 904L watch cases, casebacks, and bracelets including a 250 ton press to stamp the initial cases.
Rolex started using 904L stainless steel in 1985 in the Rolex SeaDweller and became more prevalent in the Rolex line starting in the early 2000’s transitioning from 316L stainless. Rolex initially started with just making the watch case from 904L and kept the bracelet 314L, but in 2006 Rolex utilized 904L in both bracelets and watch cases.
When comparing a modern Rolex with other modern Swiss watches, the visual difference is clearly noticeable. 904L has a high polish, looks warmer, and ages exquisitely. Yes, Rolex thinks of everything, including the metal that gets strapped onto your wrist.