Dr. Ito's thorough analysis of mechanical watches!! Vol.18 ~ About the materials used in wristwatches ~

Good evening, everyone!

In this column, I'll be discussing mechanical watches from an engineer's perspective. For the 18th installment, the topic will be:

"Materials Used in Wristwatches"

I'll be talking about this theme.

The materials used in wristwatches vary widely—some are light, some are heavy, some are prone to scratches, and others are not. A major factor contributing to this variety is the case "material." By thoroughly understanding the characteristics of each material and what applications they are suited for, you will undoubtedly be able to enjoy your wristwatch for many years to come.

Therefore, this time, I will focus on "materials" and explain them.

Please read until the end!

Common Materials Used in Luxury Watches

① Stainless Steel 

The most popular material in the world of mechanical watches, adopted in countless models, is "stainless steel."

Stainless steel is composed of metals and elements such as iron, chromium, and nickel. Its name comes from "stain" and "less," meaning it doesn't rust. As the name suggests, its greatest features are its resistance to rust and its high hardness and stable durability.

However, there isn't just one type of stainless steel; countless variations exist depending on the application, cost, and design. The material most commonly used in watches is likely "SUS316L."

Furthermore, various manufacturers hold patents and registered trademarks for stainless steel based on its constituent components and properties. Rolex, for example, uses "SUS904L," which was originally used for medical purposes, as "Rolex Steel."

Stainless steel is a material that balances cost and performance well and is easy to handle, making it recommended for everyone.

② Gold and Platinum

"Gold" is a material admired and supported by many people. Its elegant, beautiful luster and market-recognized value exude a luxurious atmosphere.

Generally, 18K gold is used in wristwatches. This is because 24K gold is too soft as a metal, so 18K, which combines other metals to increase hardness while maintaining beauty, is considered optimal.

*Carat (K), indicating gold purity, expresses the gold content in 24 divisions.

Additionally, there are three main types of gold: yellow gold, pink gold, and white gold. These colors are achieved by mixing silver, copper, palladium, and other metals.

There are a few caveats to consider: while gold and platinum are resistant to rust and can be used for long periods, they are not particularly scratch-resistant materials. If you wear your watch daily, it's inevitable that it will acquire minor scratches, so it's important to be aware of this.

Furthermore, gold and platinum are dense, making them inherently heavy. While this weight can be one of their appeals, they are not suitable for those who prefer lightweight watches.

Special Materials Used in Luxury Watches

① Ceramic

Ceramic is an overwhelmingly scratch-resistant material for watch cases. It is lighter than metal and possesses a Vickers hardness of "2300," comparable to sapphire crystal, making ceramic more than 10 times harder than stainless steel. In addition, ceramic does not discolor and does not rust. It can be said to be a material with significant advantages.

However, it requires advanced technology for processing and is manufactured through firing and other processes, which tends to increase production costs.

② Titanium

Titanium's appeal is undoubtedly its lightness. It is a lightweight material with a specific gravity of about 60% that of stainless steel. Because it is comfortable to wear, its use in watch cases has been increasing.

Other noteworthy points include its resistance to rust when exposed to seawater, thanks to an oxide film on its surface, its strength, and its low likelihood of causing metal allergies.

On the other hand, it has manufacturing challenges due to its difficulty in processing. However, in recent years, with advances in technology, the number of titanium cases with beautiful finishes has increased. It's still fresh in our minds that the 'Yacht-Master' with "RLX Titanium" debuted as a new model in 2023.

③ Bronze

Everyone wants to keep their watch in pristine condition, but recently there has been an increasing demand for watches with a unique aged aesthetic from secular change. Brass is generally known as a case material that allows for enjoyable aging, but it inevitably gives a cheap impression when used in luxury watches.

That's where "bronze" material has gained attention. Bronze, as its name suggests, uses "copper" for the case. Generally, bronze has weak anti-allergy properties and is prone to rust, so it is rarely used in luxury watches. However, brands like Tudor, Panerai, and Bvlgari have intentionally adopted bronze as a case material, creating models that boast "the enjoyment of aging through secular change."

With its unique beauty, it's a perfect material for those who find regular watches uninspiring.

Summary

How was it? 

Everyone has different criteria for choosing a watch; the elements they value may vary, such as the brand, movement performance, or dial color. I hope you will also pay attention to the case material as a key point in your future watch selections.

I hope this article provided valuable information and sparked even a little interest in luxury watches! If you have any questions, please feel free to ask directly, and I will be happy to answer them thoroughly. We look forward to your visit and inquiries.

Look forward to the next installment! See you then!