For centuries, bronze was the metal of legends: forged into weapons for heroes, cast into monumental sculptures for emperors, and utilized for maritime instruments that guided explorers across vast oceans. It is a material inextricably linked to history, utility, and the relentless passage of time. In modern horology, no material offers a more intimate or expressive connection to its wearer than bronze, and no timepiece embodies this duality quite like the CORE Timepieces STONED series. We can imagine Alexander the Great sporting the STONED Lapis Lazuli dial. Lapis was the stone of pharaohs and royalty, symbolizing the heavens and divine power—a necessity for a king who claimed godhood. Critically, the world’s most prized Lapis was mined in Badakhshan, a territory conquered and integrated into Alexander’s vast eastern empire.
Today, the bronze watch phenomenon is defined by one core characteristic: patina. More than simple aging, patina is the organic, unique layer of oxidation that forms on the case, transforming a bright, golden-hued watch into a dark, complex, often verdigris-kissed artifact. Every scratch, every swim in the sea, every humid summer day is recorded chemically on the surface, making each STONED timepiece a truly singular object—a wearable diary of the moments it has shared with you.
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Yet, bronze presents a paradox for the enthusiast. Should you celebrate its inevitable transformation, encouraging the dark, earthy hues and sea-green crusts? Or should you strive to maintain its factory-fresh luster, periodically erasing its history to reset the canvas? Understanding this process—and mastering the techniques of both acceleration and restoration—is the key to unlocking the full potential of your STONED watch.
The Science of Soul:
Why Your Watch Changes Color
To appreciate patina is to understand the chemical reaction at its core. Bronze is an alloy, typically a mix of copper and tin (in watchmaking, alloys like CuSn8 or CuAl are common). It is the high concentration of copper—usually between 85% and 95%—that is responsible for the material’s celebrated metamorphosis.
When a CORE STONED case is exposed to air, oil form the skin, and moisture, the process of oxidation begins immediately. Unlike steel, which forms a dense, non-porous layer of chromium oxide that protects the metal (making it “stainless”), copper reacts to form various compounds that visibly change the watch’s appearance.
The initial stage, often seen within days or weeks of ownership, is the formation of cuprous oxide…. This is a red or brown layer that dulls the original golden finish, resulting in the deep, warm, almost tobacco-like brown patina that many collectors prefer. This layer is protective and relatively stable.
However, the real show begins when the bronze is exposed to specific environmental factors: salt (from sweat or seawater), sulfur (from pollution or chemical treatments), and carbon dioxide. Over extended time, especially in marine or humid environments, the brown layer reacts further with these elements to form copper carbonates and copper chlorides. These complex compounds are what create the stunning, rugged blues and greens, commonly known as verdigris.
Crucially, this patina is not a weakness; it is a metallic shield. As the STONED case patinas, this oxidized layer creates a stable barrier that inhibits further corrosion beneath the surface, a quality that originally made bronze invaluable for ship fittings and diving helmets. Your watch is not deteriorating; it is strengthening its defense, all while visually registering its unique journey.
Encouraging Character:
How to Accelerate Patina
For many owners of the STONED series, the natural aging process is too slow. They want the rich, historic character now, to perfectly frame the immutable beauty of the STONED’s gemstone dials; Tiger’s Eye, Malachite, or Lapis Lazuli. Fortunately, bronze is highly receptive to forced patination—a common technique borrowed from bronze sculptors seeking to instantly age their work.
Here are two popular, yet controlled, methods for speeding up the transformation…. We are not responsible for any damage done to your watch…. making our lawyer happy (Hi Sal) and with that said……
1. The Sulfur Chamber (The Egg Method) The simplest and most accessible method, relying on the sulfur found in a hard-boiled egg.
Process: Remove the watch strap and ensure the crown is screwed down tight. Hard boil one or two eggs. While still hot, crush them into a sealable plastic container. Place the watch on a small pedestal (ensuring it doesn’t touch the eggs) and seal the container. The fumes, rich in hydrogen sulfide, will rapidly react with the copper.
Result: Produces a deep, even, dark brown or black patina, perfect for those who want a rugged, almost oil-rubbed look to contrast the STONED’s vibrant dials.
Duration: Check the watch every 10–30 minutes, as the process is highly dependent on humidity and temperature.
2. The Nautical Bath (Salt & Vinegar/Ammonia Fumes) This method replicates the conditions of a corrosive marine environment and is ideal for achieving the coveted sea-green or blue verdigris.
Mix hot water and coarse salt. Dip the bronze case into the solution briefly. Then, place the still-wet watch on a platform inside a sealable container. Pour household ammonia or white vinegar into the container below the platform. The liquid should not touch the watch.
The acid fumes from the liquid, catalyzed by the salt residue, encourage the formation of copper chlorides and carbonates, resulting in blue-green highlights.
This method can work within minutes, so vigilance is key. It allows for layered patinas—you can rinse and repeat multiple times for depth.
The Reset Button:
How to Remove Patina
One of the great pleasures of owning a bronze watch is the knowledge that the aging process is entirely reversible. If you decide the dark, crusty aesthetic no longer suits your mood a quick chemical reset is all it takes.
The fundamental principle for patina removal is mild acid. The acids dissolve the oxidized copper compounds and copper carbonates) without damaging the underlying metal or, more importantly, the critical seals and gaskets protecting the movement.
1. The Citrus Soak (Lemon Juice) Lemon juice, containing citric acid, is the simplest home remedy.
Remove the strap and ensure the crown is firmly screwed down. Submerge the entire case in a small bowl of fresh lemon juice.
Watch the case closely. The transformation often begins in under five minutes, as the lemon juice reacts and lifts the dark oxidation. For heavier, older patinas, it may require a soak of 15–30 minutes.
Once the desired original finish is restored, rinse the watch thoroughly with clean water and dry it completely with a soft cloth.
2. The Tomato Trick: Tomato paste or ketchup contains mild acetic and citric acids that work similarly to lemon juice but are less aggressive, making them a safer, slower option for a uniform clean.
Apply a thin, even coat of tomato paste to the bronze case.
Let it sit for 30 minutes to an hour. The acid slowly breaks down the patina. Rinse and wipe clean.
The CORE Duality
The bronze case of the CORE Timepieces STONED series creates a dramatic, philosophical contrast with its dial. The bronze is a record of chaos: the environment, your body chemistry, and the elements—it is mutable, earthy, and temporary. The dial, however, is a snapshot of eternity. Whether it’s the deep cerulean blue of the Lapis Lazuli flecked with pyrite (gold dust) or the swirling green of the Malachite, these dials are gemstones, products of millennia of geological stability.
This duality—the constantly evolving bronze exterior embracing the immutably beautiful gemstone interior—is what elevates the STONED series from a mere watch to a horological sculpture. When you wear a bronze STONED, you are not just wearing a time-telling instrument; you are wearing a piece of art that ages with you, ready to be reset and start its story anew whenever you choose. The choice to embrace the patina or erase it is entirely yours, reinforcing that, with CORE Timepieces, your story is always the one that matters most.
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