In Fine Watchmaking, we often see a deep and textured blue hand. This type of hand may be described in many magazines or specialized watch websites, and is often referred to as a "blued steel hand".TUDOR Black Bay M7941A1A0RU-0003 Although the name and the look of the hand go well together, we wondered what the difference is between a blued steel hand and a regular hand.

In fact, some entry-level brands or more affordable models also have blue hands, but they are fundamentally different from the blued steel hands found in fine watches. As a result, despite the blue color appearance of both,TUDOR Ranger M79950-0001 there is still a large difference in texture and visual luster. This can be appreciated if viewed using a microscope of more than 10x.

Usually, the blue hands used in low-end entry-level models are coated with layers of colored lacquer to create a blue hue. In contrast, the blued steel hands used in high-class watches are a process in which hands made of stainless steel are quenched (the metal is heated to a certain temperature and then cooled sharply in mineral-laden water, oil, or air to increase the hardness and strength of the metal) after being quenched by hand.

The process of blued steel hands is not mysterious. First, the metal is calcined to a certain temperature, then hardened by heating and hardening, and finally quenched. After this treatment, the metal pointer takes on a light blue color, which is called baked blue.

The blue color of steel is actually an oxidized layer on the surface of the steel. When steel parts are heated to a specific temperature, a color change occurs. Different temperatures produce a variety of colors. During the hardening process, the surface of the metal begins to oxidize and hardness increases along with corrosion resistance. During this process, the metal will gradually change color from its original silver-white color in the order of yellow → purple → blue → gray. Therefore, the color of a blued steel hand appears at the end of the hardening process.

Those who are familiar with blued steel hands may know that when viewed under magnification, the craftsmanship details of blued steel hands are more subtle and textured than traditional steel or lacquered hands. This is because stainless steel hands need to be meticulously polished and cleaned before they are heated to ensure that there are no spots or blue color variations across the entire surface of the fired part. If the blue color is irregular or there are spots or other defects, the polishing and cleaning must be repeated and then the bluing process must be repeated again. Grease stains, dirt or dust particles on the metal surface can cause the part to heat unevenly, which can result in the creation of noticeable spotting imperfections.

Baking stainless steel hands to a consistent and full blue color requires controlled temperature and time. For this reason, blued steel parts are often hand-treated by watchmakers in premium brands to ensure that the quality of the blued steel hands can be mastered. This also means that making blued steel hands is more labor-intensive and costly than regular hands.

If we have access to a fine watch with blued steel hands, we can get close enough to appreciate its stunning color and detail. Because it is more rare than normal hands, the scrap rate is extremely high. The slightest imperfection or over-hardening means it has to be discarded. Not only does it serve a decorative purpose, it also enhances the clarity of reading the time and is less prone to corrosion and rust than traditional steel colors.