With watch brands like Ball starting to use 904L stainless steel, taking the bragging rights away from Rolex, we thought now is the perfect time to explore the differences between 316L and 904L – at least when it comes to watches.
The industry standard stainless steel is 316L. In addition to watches, this alloy is also commonly used in the food industry, the medical field, and a wide variety of water and marine applications. You may see some watch brands refer to 316L as surgical grade steel or marine grade steel. Its popularity in these areas comes from the properties which make it resistant to rust and corrosion. 904L steel takes the resistance to corrosion up a notch.
Rolex 904L Steel:
In the watch community, 904L is largely regarded as being a Rolex thing. Even the Wikipedia entry for 904L stainless steel has been edited to include a Rolex mention (well done, Rolex!):
“In 1985 Rolex became the first wristwatch manufacturer to utilize 904L grade steel in its watches. Rolex chose to use this variety of steel because it takes a higher polish than other grades of steel and provides greater corrosion resistance, though it does not machine as well and requires specialized equipment to be properly modified into the required shapes.”
Perhaps Rolex deserves credit for being recognized as the first brand to sell watches with cases made out of 904L steel, but this has led many to think that 904L was a Rolex invention or a material exclusive to Rolex.
It could also be due to the verbiage around the term Oystersteel, which Rolex defines as:
“…a steel alloy specific to the brand. Oystersteel belongs to the 904L steel family, which is particularly resistant to corrosion and acquires an exceptional sheen when polished.” -source
Notice how it says it is an alloy specific to Rolex? Rolex has another blurb on their brand history page that claims they use their own alloy of 904L steel:
“Rolex’s steel watches are manufactured from Rolex’s own 904L alloy, known as “Oystersteel” from 2018.”
This is interesting because one would assume an alloy is determined by the properties that compose it. In other words, if it is “Rolex’s own 904L alloy” then wouldn’t changing the composition mean that it is no longer pure 904L steel?
Is 904L steel a precious metal?
To say Rolex is serious about their 904L steel is an understatement. Their advertisements have gone as far as calling it a precious metal (gold and platinum are precious metals).
Like the vintage Rolex ad above, several areas of their current website (as of 4/2021) also compares 904L steel to precious metals…
“Most commonly used in high-technology and in the aerospace and chemical industries, 904L steels are comparable to precious metals for their anti-corrosion properties and acquire an exceptional sheen once polished.” -source
And again here:
“904L steels are commonly used in high-technology and in the aerospace and chemical industries. Their excellent anti-corrosion properties are comparable to those of precious metals. Rolex masters in-house the entire manufacturing process for its 904L steel watch components.” -source
Ah, so that explains how a stainless steel watch can cost over $10,000…
Rolex and their use of 904L steel has largely gone unchallenged in the watch industry for decades. Now, as brands scramble find any competitive edge in a saturated market, we’re seeing other watch companies start to jump on the 904L train. But is 904L really that much better?
316L VS 904L Steel Composition:
We’re watch enthusiasts, not metallurgists, but the chart below sums up the main property differences between 316L and 904L steel:
316L Steel 904L Steel Carbon 0.035% max 0.2% max Chromium 16-18% 19-23% Copper 0 1-2% Iron Balance Balance Molybdenum 2-3% 4-5% Manganese 2% max 2% max Nickel 10-12% 23-28% Phosphorus 0.45% 0.03% max Silicon .75% max 1% max Hardness (Rockwell) 95 70-90 Hardness (Brinell) 217 150 Sources: Information was found in datasheets here and here, as well as on wikipedia here and here. Hardness was found here and here.
As you can see, the biggest difference when it comes to using 316L/904L for steel case and bracelet material in watches, is that 904L has a higher percentage of nickel and chromium, as well as the addition of copper.
904L also has an advantage when it comes to corrosion resistance, thanks to the copper and extra molybdenum:
“The addition of copper to this grade gives it corrosion resistant properties superior to the conventional chrome nickel stainless steels, in particular to sulphuric, phosphoric and acetic acids. However, there is limited use with hydrochloric acids. It also has a high resistance to pitting in chloride solutions, a high resistance to both crevice and stress corrosion cracking. Alloy 904L performs better than other austenitic stainless steels due to the higher alloying of nickel and molybdenum.” -source
The same resource also points out that 904L is non-magnetic in all conditions, an excellent quality to have when it comes these extremely sensitive little machines!
Does 904L cost more than 316L steel?
In our search for this answer, it became clear that pricing information on 316L is more readily available, as well as scrap prices and overall availability. 316L appears to be more widely used and readily available in various sizes and quantities. 904L is obtainable, but there is far less pricing information out there.
From what we gathered, based on comparing roll, sheet and tubing prices on Alibaba, Amazon and eBay, the 904L steel prices were approximately 2-3 times greater than 316L. The difference in price may not be significant to the amount needed to produce watches (compared to building material), which could also explain the below $2,000 USD price point of the new Ball Watch Roadmaster Icebreaker in 904L.
However, when it comes to manufacturing watch components, most factories are set-up for working with 316L steel. Does using raw 904L steel require a difference process or different machinery? It is said that Rolex has invested heavily in developing machines that allow them to work with 904L in-house, this statement from their 904L marketing video (see above) backs it up:
“…a steel so incredibly difficult to machine, that special equipment had to be built. Only one watchmaker would consider using it: Rolex.”
It is the watch industry after all, so this claim may just be the result of marketing smoke and mirrors. According to this site (which proclaims to be the leading online publication for the Materials Science community), 904L is no more difficult to work with than 316L:
“Grade 904L stainless steels are high purity steels with low sulfur content. They can be machined using any standard methods.”
Should I buy a watch with 316L or 904L steel?
The biggest deciding factor in purchasing a watch made from 316L vs 904L steel could be if you have reactions to nickel touching your skin. Although, technically 316L has nickel too, so titanium is probably the best choice for nickel allergies. Likewise, if you prefer a shinier finish on your steel watches, the higher chromium in 904L will likely be more attractive to you.
Quick FAQs / TL;DR
There is so much misinformation being spread by other watch blogs and sellers on the topic of Rolex 904L steel. Let’s clarify some things:
Is Rolex the only watch brand to use 904L steel?No.
Is 904L steel a Rolex invention?No.
Was Rolex the first watch brand to use 904L steel?Yes, as far as we know, but there are a lot of “firsts” in the watch industry that aren’t actually firsts. As for Rolex being the first on record or the first to market their use of 904L, yes, they were first (circa 1985).
Update: There are comments below stating that Omega was first to use 904L in their Ploprof diver (circa 1972), if that is true, then, in addition to the Wikipedia entry quoted above, Omega should be contesting this statement posted on Rolex’s history page: “In 1985, Rolex became the first watchmaking brand to use this steel from the 904L family for its cases.”
What was the first Rolex watch to use 904L steel?Sea-Dweller.
Why did Rolex switch to 904L steel?They claimed it was because the threading on the caseback of 316L was capable of corroding, which would allow water to get into the case and pose a potential issue to the folks using the watches as actual tools. Have you ever seen tiny rust spots around the edge of the case when you take the back off? This is why.
Is 904L steel better than 316L steel?It depends on the person wearing the watch, where they are wearing it and how they are wearing it.
Is 904L steel harder than 316L?No.
Does 904L look shinier than 316L?Yes.
Is 904L easier to polish?It sure seems like it. It is known (at least on our side of the watch industry aka pre-owned) that Rolex watches using 904L steel clean up nicely after being refinished. This could be due to the shinier finish 904L steel gives off, but also keep in mind that a watch’s ability to clean up nicely has almost everything to do with the design and flow of the finish. For example, an all satin Oyster bracelet is 10 times easier to brush out with a Bergeon wheel and restore to like new condition than an Omega Seamaster bracelet with mixed satin/polished links the require multiple steps of taping/refinishing. For that reason, many watch sellers will quickly clean up a Submariner or GMT-Master II, but will leave an SMP as-is.
Is 904L steel worth the extra cost?There shouldn’t be a huge difference in cost associated with individual watches made from 904L steel. If the cost of a 904L steel watch is significantly higher, it’s probably because of something else, not the steel itself.
Bonus: What is STEELINOX?In French, the word for “stainless” is inox or inoxydable. In metallurgical terms, inox steel is stainless steel. “Steelinox” is simply the Rolex way to say it, duh!
What is your experience with watches in 316L vs 904L? Comment below…
Thank you for reading! If you enjoyed this article about the different types of stainless steel used in watchmaking, check out the SS watches in our store or see some of the latest editions below: