In-Depth: The Patina Diaries: Living With The Tudor Black Bay Bronze

The Black Bay Bronze is one of those watches that, whether intentionally or not, serves as a reminder that nowadays, a lot of us find it hard to settle down and make a commitment to That One Special Watch. The whole point of the Black Bay Bronze, I think, is to watch it gradually change, from one day to the next. Seeing the patina on the bronze slowly begin to darken the original, almost milky-gold hue of the bronze of the case is an enormous pleasure, taken one day to the next, and if you get one, and it just sort of goes into the rotation so that every time you see it, it's drastically different, takes a lot of the joy out of it. If you do decide to make the leap of faith, though, you get an experience you can't quite duplicate with a more conventional case material, and, moreover, one that adds a really unexpected dimension of depth to what seems at first to be just another (albeit very well done) tool watch.

Before getting into the question of patina, let's talk about the overall wearing experience a bit. If you're already the owner of a previous Black Bay model there are not a lot of surprises here. The Black Bay Bronze is marginally larger than earlier models (43 mm versus 41 mm), however the case thickness is the same (12 mm), so the size difference isn't especially marked. The Bronze is heavier than the steel model, though not dramatically so; weighed without the straps attached, the steel Black Bay comes in at 78 grams, while the Bronze comes in at 94 (the difference, 16 grams, is the weight of four quarters; an Apple Watch is about 46 grams, just for comparison). The increase in size was, to me at least, noticeable but not dramatic, both visually and in feel, and I don't think that the extra few grams and couple of millimeters are in and of themselves deal breakers if you're interested in a tool and/or dive watch in the first place.

This is all by way of saying that if you own a Black Bay already, or if you've tried one on, there aren't a great many surprises to be found in the Black Bay Bronze. Having worn a Black Bay Black for quite a while as an owner, I found the transition to wearing the Bronze for several weeks pretty seamless. Other than the material and the slight increase in size and weight, one other difference between the two is the presence of Arabic numerals at 3,6, and 9, while of course on the other Black Bays, there are stick markers at the quarters (both have the triangle marker at 12:00). To my eye the use of Arabics seems to work well on the slightly larger dial of the Bronze (the inner diameter of the bezel for the Bronze is about 31 mm, versus about 29 mm for the "standard" Black Bay, as measured in our office). I think they would have felt a bit crowded on the standard Black Bay but on the Bronze, they fit the proportions and size of the dial quite nicely.

The other major difference between the two is the movement. Tudor caliber MT5601 is a movement designed for accuracy and durability, with a balance bridge rather than balance cock for better resistant to shock, a silicon balance spring, and a free-sprung adjustable mass balance. There's a 70-hour power reserve. Given the resistance of silicon to magnetism as well as the overall feature set of the movement, it should perform very well, and in nearly a month of wearing the Bronze I didn't find the rate to vary much at all – there was a net loss in daily wear of about a second every three days, which is stellar performance. I'd have preferred a net gain over a net loss, I suppose, but if this is typical performance from MT5601, I don't think too many owners will have anything to complain of.

The Black Bay Bronze was very comfortable to wear on either the provided leather strap or the fabric strap – incidentally, both extremely well made and a great fit visually to the Black Bay Bronze.

Now, let's talk about the patina.

The development of patina is a natural process in all bronzes. Bronze is a combination of copper and tin, and it was the first metal alloy used extensively in human civilization. Hard and capable of taking an edge, it was used extensively for weapons (Homer, in the Iliad and Odyssey, calls it "pitiless bronze"). Both copper and bronze can be used for external finishes (in architecture, for instance, as exterior cladding) and both develop a patina, which can take on different colors depending on atmospheric conditions and, in the case of bronze, the type of bronze used. The patina itself is the result of copper oxidizing from exposure to air, and is usually a combination of copper chlorides, sulfides, and carbonates (if the air's clean, mostly carbonates). Bronze patina is hard and can't be scratched off easily, and forms a stable surface layer that resists further oxidation.  

"Bronze disease" can occur when an excess of chlorides are formed, and while bronze patina isn't progressively destructive to the underlying metal, bronze disease can eat away at it until the entire object is destroyed. This is especially a problem in marine applications, where aluminum bronzes are preferred. This is because aluminum bronzes resist oxidation better, and the aluminum oxides that form in the patina provide superior corrosion resistance (as well as discouraging the formation of copper sulfides). For this reason, Tudor's used an aluminum bronze for the Black Bay Bronze.

Fresh out of the box, the Bronze has a pleasing, pale gold color, but as the patina develops the surface darkens. The overall feel becomes much more tool-like, and while the initial glow is lost, what you get is something much more characterful, whose slow transformation seems to give it a life of its own.

I really enjoyed watching the patina develop  As it does, you might occasionally notice a bit of green on your skin – from my experience, this happens mostly in the early stages of the formation of the patina, while the stable outer layer is developing, and it tends to diminish as time goes on. The darkening of the bronze also starts to give the case a very interesting contrast with the pristine gold of the lume plots and the hands, and the whole watch takes on a very different kind of appeal than it did fresh out of the box. You really do get the feel of having a purpose-made instrument for marine exploration on your wrist, and even (or especially) if you're not a diver, you feel a bit closer to the undersea world than you might with a conventional stainless-steel dive watch. The fittings on both straps are made of marine-grade aluminum bronze as well and will darken along with the case. There seems to be a little bit less of a tendency for discoloration to stain the skin on the fabric strap, which holds the case edges up a bit higher from the wrist than the leather strap.

The back of the case is PVD coated stainless steel, in order to prevent excessive skin staining. The first bronze-cased wristwatch, by the way, was made by Gerald Genta in the late 1990s: the Gefica; and since then the use of increasingly corrosion resistant bronzes as well as corrosion-resistant metals like stainless steels and titanium for the case backs, has become more and more common.

I had a lot of fun wearing the Black Bay Bronze. It's a large, bold but not garish, very well made watch with just enough of a different feel to stand out from the rest of the Black Bay crowd and offer its own, unique proposition. And at $3,975 I think it's a fantastic value.  

It raises, also, some interesting thoughts about where Tudor stands with respect to Rolex, especially with the in-house movement starting to find its way into more and more Tudor watches. Obviously, Tudor offers a different, more affordable, and in some ways, more down-to-earth kind of watch than Rolex. What the two do have in common, however, is fantastic fit and finish at their respective price points, and, in the tool watches, a very compelling technical value as well. The Black Bay Bronze, in this context, is I think a great addition to Tudor's lineup – it's not, after all, a lesser version of a Rolex, as it's a watch I don't think Rolex would ever do. What it is, however, is a terrific Tudor wristwatch (with the caveat that you have to be into the whole patina thing) and one that offers a delightfully different take on the Black Bay's vintage inspired vibe.

The Tudor Black Bay Bronze: case, 43 mm aluminum/bronze alloy. Bezel, unidirectional, bronze with anodized aluminum insert. Movement, Tudor caliber MT5601, 70-hour power reserve, amagnetic silicon balance spring with balance under balance bridge, bidirectional automatic. Price is $3,975. For more, check out Tudor Watch online.

For more images of the watch fresh from the box, check out our first hands-on coverage right here.

If you're a Black Bay fan, John Mayer's Black Bay Black "Week On The Wrist" is a great read.