With the move from pocket watches to wristwatches a new element had to be taken in consideration – the watch band or fastening element in general. The first watch bands (or watch straps) were made of leather, textile or metal then followed by rubber and other more innovative materials. The most exclusive watches tend to have either leather straps or metal bands. Metal bracelets are in general the most durable ones and wear well in all kinds of weather conditions and usage occasions. Their lifespan might be as long as the one of the watch itself while all other kind of bands/straps might require replacement over more or less long periods of time. In this chapter we will focus on the metal bands and explore some important factors to consider when choosing the type of metal and treatment (other materials might be covered in future posts).
One of the first metals being used for the metal band of wristwatches was gold. This has been driven mainly by two factors: i) watches were originally designated only for the most affluent people and ii) gold (and related alloys) is one of the most malleable and easy to craft materials. Over time, while gold alloy remained the top metal of choice in luxury timepieces, the introduction of steel, titanium, platinum and ceramic increased the choice and also gave more breath to the creativity of watchmakers. Ultimately, with the “democratization” of the wristwatches the stainless steel became the first choice among the different metals. Each metal has its own benefits in terms of durability, cost and aesthetic appeal, and the ultimate decision on the material choice often comes down to personal preference.
The materials used to manufacture bracelets for wristwatches are generally divided into precious vs not precious. The precious materials are the most rare, high value ones like gold and platinum. On the other hand the non precious materials are generally ferrous based like stainless steel.
Gold is the “king” of the materials. Because the many good properties and in particular sheen and malleability, this material has been used since ever to craft unique piece of art and jewelry. Its rarity coupled with the desirability made it one of the most valuable metals and still today it represents wealth and luxury.
The value of gold, as a commodity, has been steadily increasing year over year with spikes in the eighties and then again in 2008 during the latest world economic turmoil. Since then the price of gold has dramatically increased from about $900/ounce in 2008 to $1’800/ounce during 2011 to then slightly drop in the latest couple of years (currently around $1’250/ounce).
Gold is a yellow metal used throughout the watch and jewelry industry in a variety of ways. It is generally used as an alloy with other materials (e.g. silver, copper and zinc) to enhance the mechanical properties like hardness and mechanical resistance in general. The most commonly purity levels used in wristwatches is the 18 karat which relate to 75% of gold in the alloy. Gold alloys are also used in order to create different shades of gold - pure gold alloyed with silver and copper produces yellow gold, while combined with nickel, copper, and palladium (sometimes zinc) it leads to a white shade of gold and alloyed with copper and silver generates the red/pink gold.
Gold is quite dense hence bracelet and watch cases made with this material might be quite heavy. For this reason, sometimes, watchmakers use alternative materials and add gold plating on top. For example gold vermeil is based on sterling silver then covered by a layer of gold and gold plated bracelets employ a base metal (usually steel) which is then electroplated with gold. However, the durability of those treatments is generally a limitation.
Out of curiosity one of the most famous Rolex is made of solid gold (18k) and was donated by Rolex to Dwight D. Eisenhower in 1951 for helping save Europe from the Nazis. On the other hand one of the most recent watches with gold band is the Cadenas by Van Cleef & Arpel with a price tag between €37k and €160k despite having a simple quartz movement - which proves the added value given by metal, decorations and brand name.
Similarly to gold also silver has been used in jewelry for long time and most likely for the same reasons. In fact pure silver, like gold, is also malleable and sheen. However, silver tends to tarnish very easily and for this reason it is not commonly used on bracelets for wristwatches. The aesthetic qualities of silver can, instead, be achieved with other materials like stainless steel, platinum or even white gold.
Platinum is a silvery, white metal that is extremely rare and perceived as more precious than gold – even though during the latest few years gold became more expensive than platinum (currently about $1’200/ounce for gold vs $1’000/ounce for platinum). Thanks to its perceived value and very good mechanical properties this metal has become a trend in the jewelry industry. Generally used at 95% purity this metal resists well abrasion. In fact, when a platinum surface gets scratched the material just gets displaced instead of being removed and lost like in other materials. For this reason scratches can easily be polished to bring the surface to the original status. Another great advantage of platinum is that (like Titanium) this material is hypoallergenic so ideal for those with sensitive skin.
Platinum watches are usually the most expensive timepieces on sale and if one embarks on this choice then it is worth checking the “stamp” which should read "PLAT", “platinum” or “PT” (indicating minimum of 95% of platinum) and not "IRID/PLAT" which indicate alloy of platinum.
An interesting solid platinum bracelet is the one used in the Rolex Datejust 6604 (1957) because of its original woven structure. It is also worth mentioning the IWC Grande Complication ref 927016 because its beautiful “studded” platinum bracelet.
After Platinum, Titanium is the metal that is getting more and more traction in the watch and jewelry industry. In fact, Titanium is a very valid alternative to Platinum – it is silver-white colored and it is very hard (stronger than stainless steel and platinum) yet very light weight and also 100% hypoallergenic. Interestingly enough those properties are not accompanied by an high price tag as Titanium is generally more affordable than materials like gold, platinum and palladium.
Titanium is available in different grades (28 grades scale) depending on whether pure or alloyed and depending on the treatment it has gone through. The most commonly used titanium grade for wristwatches is grade 5 – which indicates an alloy containing 6% of aluminum and 5% of vanadium. Other grades (e.g. 1-4) are also available though those generally are less appreciated for their inferior mechanical properties (but more affordable).
One of the key advantages of Titanium is also a disadvantage – in fact its hardness makes it difficult to work and manufacture precise pieces and this drives up the cost of elements made of this material. Also, the fact that Titanium is a lightweight material (about 45% lighter than steel) might be a property appreciated by some but it can also be perceived as a negative by others – heavy weight is generally perceived as higher value. For the above reasons many brands tend to offer Titanium bracelet as an option – for example, both the Richard Mille RM 011 Felipe Massa and the Hublot Big Bang UNICO are also available with Titanium bracelet option.
Nowadays stainless steel is the most favorite material for both men and women. This material is the most versatile and is used in watches for both classic and sport occasions while at the same time being very accessible from a cost perspective.
In fact during the great depression (about 1930), watchmakers were looking for an alternative metal more affordable than gold and other expensive metals used till then yet resistant to corrosion. Stainless steel was discovered at the beginning of the century and at that time some companies were starting to use it in cutlery and other utensils for its ability to resist corrosion. The watchmakers, under economic pressure, then investigated this material – they discovered that despite its good qualities and relatively low cost, stainless steel was very difficult to work. For this reason this material has been widely adopted only after the introduction of new and different manufacturing methods – it seems that Vacheron Constantin and Patek Philippe were the early adopters.
Stainless steel is an alloy of iron, chromium and nickel and the most commonly used grade in the horology industry is the 316L highly resistant and malleable. Some manufacturers, however, might use different grades either for the entire portfolio or for just some specific collections. Rolex, for example, uses 904L steel in their entire portfolio – this material seems to be even more resistant than 316L and it is also capable to better hold polishes though it is more difficult to machine.
Stainless steel is also very versatile in terms of aesthetic and can be easily treated for different kind of finishes or could be coated in order to give a different color.
Notably the inclusion of nickel in stainless steel might trigger allergies in some susceptible people. This does not seem to be a widespread effect and it might also be partially mitigated by some treatments done on the surface of the metal (e.g. PVD and DLC – see later).
Less Common Metals
The metals described in the above sections are the most commonly used, however, they are not exhaustive of all materials used in the horology industry for watch bands. Even without considering the polymers, ceramics, and composites there are still many more metal materials used.
Among those there are palladium and rhodium which compete with titanium and platinum for their coloration and properties. Palladium is a naturally light grey metal (like Platinum) that is used in a small capacity as a stand-alone metal by companies like Cartier (Tank MC Skeleton) and Ulysse Nardin (Macho Palladium 950). Rhodium is particularly hard and is the most expensive precious metal – due to the low malleability it needs to be used as an alloy but more often it is just used for plating. Tungsten is sometimes considered as an alternative to Titanium though it has a very peculiar steel-gray color. Copper and brass (copper and zinc alloy) offer darker colors and became trendy over the last few years.
Watch band treatments can be classified into functional and aesthetic treatments. The functional treatments are generally executed to add new functions or improve existing characteristics of the material and will ultimately drive up the performances of the metal. Most of the time those are surface treatment and they aim at improving corrosion resistance, wear resistance and hardness (e.g. carbon diffusion). Worth mentioning in this context the process developed by Sinn / Damasko, which they call “Tegiment” to dramatically improve the hardness of the steel not only externally but also in deeper layers.
The aesthetic treatments, instead, relate to a change in aspect of the metal whether color wise or on the type of surface finish. Those effects are generally achieved either via plating and/or through mechanical action (seldom other more peculiar chemical reactions might be required).
The most common aesthetic treatments (beside the mechanical ones) are: “simple” coating, ion plating (IP) / physical vapor deposition (PVD) and Diamond-like carbon (DLC) coating. The “simple” coating (e.g. powder coating, anodization…) was originally used to give the metal a different color and sometimes intended to increase value (e.g. gold plating). However, the use of this method has been reduced over time and now is getting replaced by more sophisticated and ultimately longer lasting treatments like PVD and DLC. On the negative side the effect achieved by the new treatments is not always the same and, for example, the gold look given by PVD is not exactly the same as the one achieved by gold plating (pure gold look and feel).
Powder Coating and Black Oxide
Over simplifying, powder coating is about applying a “dry paint” on the metal surface (generally electrostatically) and then heat bond in an industrial oven. The finish achieved tends to be hard but it is still a separate layer which can be relatively easy chip off over time.
Black oxide, instead, is achieved via a chemical reaction (similarly to anodization) between the iron of the ferrous alloy and a hot oxide bath to produces magnitite. As for the powder coating, also in this case the treatment doesn’t penetrate deep into the metal hence it might not be appropriate for high wear areas.
Physical Vapor Deposition or Ion Plating
Physical Vapor Deposition or Ion Plating (which is a variant on PVD) treatments are used by both mid-range and high end watch brands. The principle is very simple – the surface to be treated is first prepared and placed in an inert environment then the plating is applied as a vapor on top at specific pressure and temperature conditions (e.g. 250°C - 600°C). If the application is done via charged ions then the process is called Ion Plating. The resulting coating (generally 2 to 5 µm) gets bonded to the base material and will not easily flake off as in other techniques (e.g. anodizing, painting…) yet it is not super resistant to scratches. In fact if the scratch is profound enough to go through the plating layer then the original material will be visible.
It is worth underlining that PVD is a process (not a material) and as such the ultimate results depends on how the many variables are used by one manufacturer vs another. Some vendors are capable of delivering PVD of very good quality – others might lead to finish with performances comparable to the one achieved with the anodization process (or even worse).
Chemical Vapor Deposition
Another variation of the PVD process is the Chemical Vapor Deposition (CVD). While in the PVD process the plating material is applied via a physical mechanism, in the CVD the application is achieved via a chemical reaction. The resulting coatings (generally 5-10 µm) has a good balance of hardness and wear resistance and can lead to even better results when the thickness of the coating is increased (Thick Chemical Vapor Deposition; T-CVD).
This technique is, however, mostly used for parts of the movement or the case rather than the bracelet itself. The Urwerk UR202 for example is also available with black case in PE-CVD (Plasma Enhanced –CVD) platinum.
Diamond Like Carbon
Diamond Like Carbon (DLC) is a class of amorphous carbon material that displays some of the typical properties of diamond. DLC is usually applied as coatings to reduce abrasive wear in the engines of modern supersport motorcycles, Formula 1 racecars, NASCAR vehicles and in general only in high value items considering the inherent cost and difficulty in finding companies able to deliver good quality DLC.
Notably DLC is not a process like PVD but a material – in fact variations of PVD process can be used to apply this material. There are different methods to apply DLC onto the surface (sputtering, ion beam, cathodic arc, electron beam, lasers…) and in order to avoid delamination a series of layers are applied to the base metal (generally titanium layers followed by DLC).
DLC is used in #YOURTIME watches in order to make them super resistant to abrasive wear so that the black color can stand the test of time. In our post dedicated to diamond-like-carbon treatment you can watch a video about the “cutter test” executed on the case of #YOURTIME watch. Despite the harsh cutter test, the black color stays on and the timepiece does not show any sign of scratches. This does not mean that DLC is immune to scratches but only that it resists to most of them and better than other treatments.
Remarkably not all luxury brands use DLC coating mostly due to its cost and limited number of vendors able to ensure good quality. Most of the luxury timepieces are, in fact, treated with more “traditional” PVD which is good but not as resistant as DLC coating. Some examples of DLC coated watches are: Linde Werdelin SpidoSpeed Steel Anthracite DLC, Panerai Luminor 1950 3 Days Titanio DLC, Magrette REGATTARE DLC and BREMONT U2/DLC Automatic Watch
To conclude, the choice will be ultimately driven by personal preference and cost constraints. However, the above should help understanding what is available and especially what to look at and ask in terms of treatment.