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Rolls Of Stainless Steel

All About 316L VS 904L Stainless Steel in Watches

Rolex 904l Stainless Steel Oyster Case

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 takes the resistance to corrosion up a notch.

Rolex 904L

To say Rolex is serious about their 904L steel is an understatement. Their advertisements have go as far as calling it a precious metal.

Rolex Precious Metal 904l Magazine Ad

Even the Wikipedia entry for 904L 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.

Rolex does deserve credit for being recognized as the first brand to make cases out of 904L steel, and this has lead many to think that 904L was a Rolex invention or a material exclusive to Rolex. This could 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

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 Composition

We’re watch enthusiasts, not metallurgists, but the chart below sums up the main property differences between 316L and 904L.

316L 904L
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
Silicone .75% max 1% max
Hardness (Rockwell)
95 70-90
Hardness (Brinell)
217 150
Information was found in datasheets here and here, as well as on wikipedia here and here. Hardness was found here and here.

Main Differences

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 source also points out that 904L is non-magnetic in all conditions, an excellent quality to have when it comes these extremely sensitive little machines!

The biggest deciding factor 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.

Does 904L cost more than 316L?

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.

Rolls Of Stainless Steel

From what we gathered, based on comparing roll, sheet and tubing prices on Alibaba, Amazon and eBay, the 904L 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. Using raw 904L may 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, this blurb on their site backs it up:

“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

It is the watch industry after all, so the paragraph above may just be the result of more marketing and misconceptions within the watch community. According to this site, 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.”

Quick Facts / TL;DR

There is so much misinformation being spread by other watch blogs and sellers on the topic of Rolex and their use of 904L. Let’s clarify some things:

Is Rolex the only brand to use 904L steel?
No.

Is 904L steel a Rolex invention?
No.

Was Rolex the first brand to use 904L?
Yes, as far as we know. 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.

What was the first Rolex watch to use 904L?
Sea-Dweller

Why did Rolex switch to 904L?
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) 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 and brings back to like new condition than an Omega Seamaster bracelet with mixed satin/polished links. 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 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!

Rolex 904l Steelinox

What is your experience with watches in 316L vs 904L? Comment below…