Interesting read on Rolex 904L Steel

[arizonapaul]

I thought this was interesting and I certainly didn't know all these cool facts. Below is copied and pasted off the net

If you ever compare a Rolex stainless wristwatch to any other stainless wristwatch, you’ll see differences because Rolex approaches stainless steel differently from other brands. Rolex approaches all its watches from a mindset of lasting durability, and the reason behind Rolex’s use of stainless steel that is different from the rest of the watch industry. Rolex utilizes 904L stainless steel for a number of technical reasons, including its highly polishable property creating a lasting, durable reflection on the watch.



Stainless steel in watches is important because of the proximately to the skin combined with sweat and moisture makes wristwatches a corrosion magnet. In order to keep the case waterproof, the threads that hold the crown and the caseback cannot corrode. Even though stainless steel is formulated to prevent rust and pits from ocean salt water and sweat, Rolex found excess wear in the caseback threads and watch case from salt water seeping into the threads and sitting undisturbed for years between watch services allowing for the steel to pit and gall. Salt and other minerals proved to be catalysts for corrosion and deterioration around the threads that hold the caseback. Noble metal wristwatches such as gold or platinum watches do not have a corrosion issue, but base metal does. Until the widespread use of stainless steel, older watches utilized primitive stainless caseback and some type of base-metal case. Nowadays, most stainless steel wristwatches are made of 316L stainless steel throughout whereas Rolex utilizes 904L stainless steel.

Rolex calls 904L stainless steel a “corrosion-resistant superalloy.” 904L differs from 316L because of extra Chromium, Molybdenum, Nickel, and Copper which 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 904L.


Rolex utilizes 904L with the greatest of quality control. Once received from Rolex’s steel suppliers, Rolex casts and scans it using 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 their exacting specifications. 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 as compared other stainless steels. Subsequently, Rolex had to design its own tools to work with the material and utilizes a 250 ton press to stamp the initial cases.

Rolex started using 904L stainless steel in 1985, but it became more prevalent in the Rolex line starting in the early 2000’s transitioning from 316L. Rolex initially started with just making the watch case with 904L and kept the bracelet 316L, but since 2006, Rolex utilized 904L in both the bracelet and case. 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.