Carbon is often presented as the Holy Grail of materials, straight out of Formula 1 and aerospace. Lightweight, ultra-strong, indestructible. Honestly, I understand why that's appealing. Everyone would love to have a watch that weighs almost nothing and can withstand anything. However, the reality of repair shops tells a very different story. First, we'll look at what carbon actually is from a technical point of view, to understand why watches costing several thousand euros can break with the slightest impact.
What carbon really is: a composite, not a metal
Unlike steel or titanium, which are homogeneous metals, carbon is a composite material. It's made of two very different things: a fiber that serves as reinforcement, and an adhesive called a matrix. Imagine reinforced concrete: you have steel bars for tensile strength and concrete for compressive strength. In a carbon watch, it's the same. You have microscopic carbon filaments that are ultra-resistant to tension, but these fibers are flexible like sewing thread. To make a hard case, you need to embed them in a matrix, usually a polymer resin like epoxy.
Fiber manufacturing begins with a material called a precursor. It's passed through very small holes to create very fine threads that are then stretched to align the molecular structure. This is what gives the fiber its strength. Then comes oxidation in a furnace between 200 and 300 degrees to make the threads infusible. This is followed by carbonization at 1500 degrees: everything that isn't carbon goes up in smoke, leaving only tightly packed carbon atoms. For an even more rigid fiber, the temperature can be raised to 2000 degrees to modify the crystalline structure and obtain what are called high-modulus fibers.
Once out of the oven, the fiber is too smooth for the resin to adhere to it. So, a surface treatment called sizing is performed through chemical electrolysis, which acts as a chemical binder with the resin. When you touch your carbon watch, you're not touching the carbon itself. You're touching the resin, like plastic. And chemically, this resin has all the flaws of plastic: it's sensitive to UV, it scratches easily, and it doesn't like chemicals.
The confusion between strength and hardness
Marketing heavily plays on the confusion between strength and hardness. It's often said that carbon is much stronger than steel. This is true, but only in tensile strength. If you hang a truck from a carbon cable, it will hold better than a steel cable of the same weight. But for a watch, tensile strength is not that important. A watch is subjected to friction and punctual impacts. And in this area, hardness is what matters.
316L steel has a hardness of approximately 190 HV. Grade 5 titanium goes up to 350 or 400 HV. Carbon fiber itself is hard, but the resin that holds it often struggles to exceed 80 HV. The result is that you can scratch a carbon watch much more easily than you think. You have to forget the idea that because it's carbon, it's scratch-proof. On the contrary. You tend to see scratches less due to the material's particular texture, but it scratches much more easily than steel or titanium.
If you're looking for a more durable alternative to carbon that avoids its everyday drawbacks, explore our collection of stainless steel bracelets, which are more resilient, stable, and suitable for intensive use.
The three main families of carbon in watchmaking
Not all carbons are equal, and not all carbon watches are equal either. There's a real technological hierarchy.
Woven carbon is the classic carbon everyone knows. You take carbon threads, weave them like fabric, stack layers, add resin, and cure the whole thing. This gives it that very recognizable checkerboard pattern. This carbon looks beautiful flat, but it's hell to make a complex case with sharp angles, because the fabric doesn't drape well into small corners of the mold. And when you machine a case from a block of woven carbon, you cut the long fibers. But carbon is only strong if the fiber is long and continuous. For example, by drilling holes in the lugs for the strap, you cut the fibers and create major structural weak points. That's why entry-level woven carbon watches often have reliability problems.
Forged carbon is the technology used by many brands, notably Audemars Piguet. Here, it's not weaving. You take carbon fibers, chop them into small pieces a few millimeters long, mix them with resin like modeling clay, put everything into a steel mold, and press while heating. The advantage: you can mold really complex shapes, curves, crown guards, which is impossible with fabric. The appearance is quite random and marbled, making each watch unique. The problem is that forged carbon is technically less resistant than woven carbon in pure tension because the fibers are short and discontinuous. And above all, it is often porous. On some models, forged carbon bezels can crumble over time with everyday bumps and knocks. This is what happened at Audemars Piguet, which eventually replaced its carbon bezels with much more resistant ceramic bezels.
NTPT is the most advanced technology, made famous by Richard Mille and directly inspired by racing yacht sails. We forget classic weaving or chopping. We use unidirectional carbon plies, extremely thin layers of about 30 microns. For context, a hair is between 50 and 100 microns. To make a single case, hundreds of layers are stacked, crossing the angle by 45 degrees each time. The advantage is massive: the threads remain perfectly straight, unlike woven carbon where the threads go up and down. A carbon fiber is never as strong as when it is rectilinear. By multiplying ultra-thin layers, the proportion of resin is minimized, and air microbubbles are completely eliminated. The result is the densest, most homogeneous, and hardest carbon. Once machined, the rendering is spectacular, with patterns reminiscent of wood grain or geological cuts. It is the highest-performing carbon in the world, but also a material so hard that it destroys cutting tools at an incredible rate, which explains its astronomical manufacturing cost.
The myth of robustness: breaking lugs
Carbon is sometimes marketed as being tougher than steel. This is extremely misleading. Steel and titanium are ductile materials: they have the ability to deform plastically before breaking. If you violently bang your steel watch against a door frame, the metal absorbs the energy of the impact by deforming. You'll get a mark or a deep scratch, which is ugly, but the watch remains intact, the case isn't broken, the water resistance is preserved, and it's always repairable.
Carbon is a mechanically brittle material, like glass or ceramic. It goes directly from its elastic phase to fracture. In the factory, if a technician drops a simple screwdriver on a carbon part during assembly, the part is almost always discarded. Even if nothing is visible to the naked eye, the impact may have created internal microcracks, which is called delamination. Under pressure in flight, the part could simply explode.
On forums and in user groups, there are many accounts of carbon watches breaking, often at the lugs. This is not surprising: carbon is very resistant to tension but very poor at shear and torsion. On a lug, there's a hole, which creates a perfect stress concentrator. This is precisely where there's the most stress when handling the strap. Generally, breakage occurs with a small impact or during strap changes.
This problem is not limited to entry-level watches. Tissot and Panerai users have reported broken lugs on their carbon watches. Some Reddit posts were deleted by their authors, probably at request, but the titles and replies remain visible. One person broke the lug of their Panerai by simply tapping their watch on the edge of their kitchen table, without even a major impact. With carbon: it either resists, or it breaks clean. There's no compromise possible.
Water resistance: a real technical challenge
To ensure a watch's water resistance, the case back must be screwed down tightly enough to compress the gaskets. If you try to thread directly into carbon and screw a steel screw into it, you'll strip the carbon threads after a few uses. You might be able to screw it in once, but when it comes to servicing and unscrewing/rescrewing multiple times, it quickly becomes a problem.
To get around this, many brands actually make an internal container out of steel or titanium, a kind of waterproof capsule that holds the movement, crystal, and screw-down caseback, and then encase this container in a carbon shell. This is a reliable solution, even if it negates some of the weight savings that were supposed to be the main argument for carbon.
Humidity and UV: the discreet enemies
One point that is almost never mentioned is that carbon doesn't like humidity very much. We tend to believe that carbon is totally inert, but it's more complex. Carbon boats spend their lives in water without problems, certainly, but they are protected by a gel coat, waterproof paint, or a thick protective varnish. In watchmaking, we want to maintain the raw, matte, and textured appearance of carbon. The watch is therefore directly exposed to perspiration, chemicals, and water. If the compaction of the layers is not absolutely perfect during manufacturing, invisible micro-voids remain. Water can then infiltrate by capillarity between the layers, causing micro-swelling and weakening the internal structure in the long term. This is why carbon is not the ideal material for a professional diving watch intended for very regular immersion.
Epoxy also hates UV. If your watch is often exposed to the sun, the resin can start to change color. On black carbon, this results in dulling, a less deep appearance that alters the aesthetic of the material. Most brands use UV stabilizers, but no polymer is eternal when exposed to the sun. Unlike ceramic, which will look the same in 100 years, carbon will inevitably change its appearance slightly after a few years.
Scratches: permanent and irreparable
If you scratch your carbon watch, it's permanent. If the scratch is superficial and stays within the resin, it appears a bit white and can sometimes be attenuated. But if the scratch is deep and reaches the fiber, there's nothing you can do. If you polish it, you cut fibers and create an uneven area. You can't restore a damaged carbon to its original luster. It's a disposable material in terms of finish: once it's damaged, it stays that way, or you have to replace the entire part.
Who a carbon watch is really for
The added value of carbon for the user is quite debatable. You pay for the manufacturing complexity, not necessarily for better daily performance compared to good grade 5 titanium. Except for weight: if you're really extreme on this point, carbon might be justified.
If your criteria are durability, repairability, and passing it down, carbon is probably a mistake. A carbon watch will age less gracefully than a metal watch and cannot be repaired in case of a major impact. However, carbon has its place if you know why you're buying it: you want an ultra-light watch for sports, you love the unique technical look, and you accept that it's a technological object that will show indelible marks over time.
The mistake isn't the material. The mistake is confusing technicality with invulnerability. It's like asking a Formula 1 car to have the ruggedness of a 4x4. If you want to change the strap of your carbon watch, do so with caution and make sure you never force it. Find compatible straps on Braxen, with lifetime guaranteed metal, NATO, and rubber straps for most 20mm watches.
