Glossary · Materials
904L STEEL (Super-Austenitic)
Definition
904L steel is a super-austenitic stainless steel with more chromium, nickel and molybdenum than 316L, plus copper. It resists acids and sweat better and takes a deeper polish. Rolex has used it for cases since 1985 and for the whole production since 2003. It is harder to work than 316L: that is why almost everyone else stops at 316L.
Frequently asked questions
What is 904L STEEL (Super-Austenitic)?
A stainless steel with more chromium, nickel, molybdenum and copper than common 316L. More resistant to corrosion, harder to work, with a deeper polish. Anyone wearing a Rolex built after 2003 knows it.
What difference does 904L steel make for the strap?
None on the leather side: the lug-to-lug width and the thickness at the attachment point remain those of the case. It matters for the buckle. On a polished 904L case, a polished 316L buckle holds its own to the eye; the difference in alloy does not show on the wrist.
How do I match a strap to a 904L steel case?
I come across 904L steel in the case and the buckle, not at the bench: I work the leather. On steel this bright, I recommend leathers with grain: coarse-grained calfskin, small-scaled alligator. Smooth, glossy leather competes with the case, grain complements it.
The next step
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