Last Updated on November 5, 2024 by Jason
Stainless steel is a versatile material that is widely used in watchmaking due to its durability, corrosion resistance, and hypoallergenic properties. It is highly resistant to rust, moisture, and sweat. This makes it ideal for timepieces and jewellery that need to withstand daily wear. Additionally, stainless steel causes minimal skin irritation, making it a preferred material for both watch cases and bracelets. In this post, we look at the different types of stainless steel that are commonly found in vintage watch cases.
Invention of stainless steel
Stainless steel was invented by English metallurgist Harry Brearley in 1913. He was working on a project to improve rifle barrels when he discovered that a particular steel alloy containing about 12-13% chromium resisted rusting.
304 stainless steel, one of the most common types of stainless steel, was developed in the 1920s. It was created through further refinements of Brearley’s initial invention by metallurgists at Firth-Vickers, a British steel company, and American engineers. They introduced nickel into the alloy, which significantly enhanced its corrosion resistance, formability, and durability. 316 stainless steel was developed in the early 1950s by metallurgists who were working to improve the properties of existing stainless steels, particularly for use in harsh environments. The invention of 316 stainless steel is generally credited to metallurgical research and innovations within the steel industry. However, there is no single individual who is credited with its invention. 316L stainless steel was developed in the 1950s as an enhancement to 316 stainless steel, which had been introduced earlier.
904L stainless steel was available in the early 1970s, although the inventor is not entirely clear. It is incredibly resistant to corrosion and slightly softer than 316L steel. It comes at a cost, 904L is sometimes considered a precious metal, costing several times more to produce than 316L steel. Omega SA was the first to experiment with 904L or ‘Uranus Steel’ with the PloProf dive watches in 1971. Rolex is another prominent user, their version of 904L is often referred to as Oystersteel.
What is stainless steel and how is it made?
Stainless steel is an alloy primarily made from iron, carbon, and chromium. The addition of chromium is what gives stainless steel its characteristic resistance to corrosion, as it forms a protective oxide layer on the surface of the metal. The general composition of stainless steel can also include elements such as nickel, molybdenum, manganese, and silicon, depending on the specific type and its intended use.
To produce stainless steel, the base metals are melted together in a furnace and combined with chromium and other elements. Once the alloy reaches the desired composition, it is cooled and solidified into the required forms, such as sheets or bars, for further processing. Different grades of stainless steel are developed by varying the proportions of the alloying elements, which can enhance qualities like corrosion resistance, strength, or formability.
Different types of stainless steel in watchmaking
There are several types of stainless steel used in watchmaking, each with distinct characteristics and levels of purity. The most common grades used in vintage and modern watches are 304, 316L, and 904L, with varying properties and applications.
304 stainless steel
304 stainless steel is an alloy that contains 18-20% chromium and 8-10.5% nickel. It is the most widely used form of stainless steel. It is found in a variety of applications such as household items, cookware, and lower-end watches.
While 304 is durable and corrosion-resistant, it is not as resistant to harsher environments as higher-grade steels. The higher carbon content of 304 steel makes it slightly less resistant to corrosion than 316L. Additionally, its appearance tends to be darker. Because of its malleability and lower cost, 304 is typically used in more affordable watch models, especially those designed for everyday wear.
316L Stainless Steel
316L stainless steel is a higher-grade alloy with 16-18% chromium, 10-12% nickel, and 2-3% molybdenum, which significantly improves its resistance to chlorides and corrosive environments. The “L” stands for low carbon content. This enhances the steel’s durability and makes it less prone to cracking or corrosion over time. This is especially important in marine or high-moisture settings.
Due to its superior properties, 316L stainless steel is widely used in the watch industry, particularly in high-end watches and dive watches. Its resistance to saltwater, chemicals, and magnetic fields makes it ideal for timepieces designed for extreme environments. Additionally, 316L is often used in medical equipment and surgical tools because of its biocompatibility. It is highly regarded for its strength, resistance to wear, and ability to maintain a polished appearance over time. 316L stainless steel will be the most common type of stainless steel found in vintage watch cases.
904L Stainless Steel
904L stainless steel is an ultra-premium grade alloy that is used primarily in luxury watchmaking. It contains 21-23% chromium, 24-26% nickel, 4-5% molybdenum, and 1-2% copper. The inclusion of copper improves the alloy’s resistance to acids. This makes it particularly suited for harsh environments such as chemical processing and pollution control systems.
Introduced in the watch industry by Rolex in the 1980s, 904L is known for its exceptional corrosion resistance and ability to maintain a superior polished finish. While more expensive and difficult to machine than 316L, it is often used by luxury brands for its aesthetic appeal and enhanced durability. Watches cases made from 904L have a distinct lustre, and their ability to resist tarnish and wear makes them stand out as premium products.
While 904L offers some advantages over 316L, the practical differences in everyday wear are minimal. Both types of steel are highly resistant to corrosion and durable. However, the 904L’s fine finish and exclusivity are its primary selling points in luxury timepieces.
Conclusion
Stainless steel’s versatility and durability made it the ideal material for vintage watch cases. The different grades offer varying levels of performance, from the more affordable 304 to the premium 904L. 316L stainless steel remains the most widely used material in high-end watches. This is due to its balance of corrosion resistance, strength, and cost. While luxury brands may opt for 904L to achieve a superior polish and aesthetic appeal, both materials have proven to stand the test of time in the world of watchmaking.
Related content
Stainless steel at Wikipedia.
Leave a Reply