The blue steel hands on the Swiss dial are not only beautiful, they are testament to the premium quality of the product.
Why is the blue steel hand a proof of high-end watch quality?
Every time watch brands introduce new products, they always point to criteria that guarantee the premium quality of their creations. One of the criteria mentioned is the blue steel hands. Why? Join Harper’s Bazaar to find out the mystery behind.
A blue needle does not mean that the steel is plated or painted blue. The main prerequisite is that the blue color must be created from the technique of bluing steel. This technique requires heating the steel until it turns blue.
The technique of greening steel requires high craftsmanship, experience, meticulousness and the hands of a skilled craftsman. These blued steel hands put the watch in a completely different segment, representing the luxury of the watch world.
In the past, blued steel was necessary. This process helps prevent rust, increases toughness and reduces brittleness of the steel, allowing for sharper and more precise shaping of watch parts.
In the past, thermometers had not been invented that were durable enough for the steel forging process, and accurate temperature recognition in watchmaking was difficult. Therefore, the artisan will observe the color of the steel to decide the stop.
Steel changes color when the element iron (Fe) in the steel combines with oxygen, during heating, forming a layer of iron oxide on the surface of the metal. Depending on the temperature, this oxide layer has a certain thickness and leads to color change.
In the case of the hands of a watch, a blue color appears at a temperature of about 300 – 310 degrees Celsius. This color informs the craftsman that the hand has achieved the right physical properties.
Not only the clock hands, other accessories such as screws also use calcined steel. Depending on the function that each steel part will be fired at different temperatures, it will determine the ductility and hardness of the steel.
If overheated, the steel will turn brown and become useless. Therefore, the process of greening steel requires skilled and experienced artisans. It is estimated that this process has a failure rate of up to 75%. Therefore, the technique of greening the steel and the blue hands of the watch is a testament to the superior quality of the product.
After polishing and cleaning, the parts to be heated will undergo a “fire test”.
First, put some copper filings in the tray and place the clock hands on top. Turn on the flame and proceed to heat, wait for the temperature to rise.
Next, move the tray in a circular motion around the flame to ensure that all parts of the clock hands are heated evenly. At this point, the artist needs to pay attention to the color of the needle. It will gradually turn straw yellow, yellow, brown, purple, dark green and then blue.
As soon as the steel needle turns blue, the artisan takes it out with tweezers and the needle cools almost instantly. The color from the moment the needle leaves the baking tray will be preserved.
If the pre-heating preparation is done well, the needle will be a uniform, spotless blue color. If the blue color appears uneven, has spots or a few spots are not right, the polishing and cleaning needs to be repeated. As can be seen, the key to owning a perfect blue watch hand is to be well prepared.
The whole process above takes place in just a few seconds. Much of the work lies in polishing and cleaning. Otherwise, it will take time at the rework stage to achieve the desired green color. The time for a perfect blue hand is often not measured until everything is done. A lot of things can go wrong, leading to an unsatisfactory blue color and prolonging the manufacturing process.
Such as grease, dirt or dust particles on the surface, alcohol stains invisible when cleaning and uneven temperature distribution on parts… All of these can become the cause of blue is wrong. That shows that a needle can perfectly be polished many times before it is finished.
And let’s not forget, the blues need to be consistent with the other parts of a watch. So even a perfect blue needle can still be reworked because of the color difference.
While the technique of greening steel played an important role in watchmaking back in the day, today it is slowly being lost as modern solutions emerge. Watch manufacturers have a wide range of options for anti-rust steel, such as plating or alloying. These solutions are effective, easy and also less expensive when compared to the green heating technique.
Therefore, the technique of greening steel becomes something of a luxury in terms of both time and manpower. Now, it is applied mainly because of aesthetics and the preservation of traditional craftsmanship.
The blue hands are made by modern technique that preserves absolute precision at a lower production cost which is very popular with high-end brands. However, handmade needles with slight color differences due to human error are still popular. For watch collectors, passionate about works of art, this is not a defect. Behind those green needles is the mark of a skillful hand from a craftsman.
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