For many beginners in the watch industry, when they first hear the term “surface treatment”, they often feel completely confused. After staring at the back of the movement for a long time and seeing various patterns, polishing, and decorations on it, they still can’t tell which ones are just for show and which ones are truly painstaking craftsmanship. The polishing of the movement does not determine whether the timekeeping is accurate or not, but it is precisely an indispensable lesson in watchmaking art. Once you understand this, when you appreciate a finely crafted watch, you will have an additional dimension of enjoyment.
What exactly is “casing finishing”?
Casing finishing, in simple terms, refers to the decorative processing carried out on the surface of the steel parts of the movement. Note: Decorative finishing ≠ Functional finishing.
Functional finishing is aimed at reducing gear friction and enhancing durability, directly affecting the operation of the movement. The Geneva pattern, fish scale pattern, and blue steel screws that we often mention mostly belong to decorative finishing, and their main function is to beautify the movement, without significantly affecting the timekeeping. Many micro-brand and budget mechanical watches also perform decorative finishing to enhance the visual appeal.
Several common patterns that beginners must recognize
For beginners, there’s no need to immediately delve into the “Geneva Twelve Rules”. Just master the most common decorative techniques, and that will be enough for you to not look out of place at the gathering of watch enthusiasts.
Geneva pattern: The “ripples” on the splint
This is the most prominent decoration on the movement, usually found on the upper bridge surface. It is a series of parallel waves, looking like ripples on the water surface.
The name “Geneva pattern” comes from the sparkling surface of Lake Geneva. At the beginning of the 20th century, Swiss watchmakers began to use this pattern to decorate movements, and it later became one of the symbols of high-quality watchmaking. Most brands use parallel stripes, while a few may use radial or concentric circles (such as Omega’s Arabic-style Geneva pattern).
How to judge good or bad? The pattern should be uniform, continuous, and have consistent depth. If the pattern is wide and rough, with blurred edges, it indicates an entry-level level.
Fish scale pattern / Pearl pattern: The “dots” on the bottom layer of the veneer
If you turn on the backplate transparency, you will see layers upon layers of small dots arranged like fish scales or pearls. This is called the fish scale pattern, also known as the pearl pattern.
This pattern is usually found on the lower layer of the bridge plate of the movement – the area that is not easily blocked by the automatic rotor. It often appears in combination with the Geneva pattern: the upper layer has waves, and the lower layer has dots. The layers are clearly distinct.
How to judge good or bad? The key lies in density and uniformity. Some tablemates have compared it, and the density of the fish scale pattern in Citizen’s high-end movement Cal. 0200 even exceeds that of Grand Seiko’s 9S65. The closer the dots are arranged and the more consistent their sizes, the deeper the craftsmanship.
Bevel: The “mirror” on the edge
In simple terms, it involves cutting off the original 90-degree corner edge of the splint at an angle and smoothing out a shiny small slope. If this slope is done finely enough, it will reflect light like a mirror.
Why is chamfering so important? Because it is the process that best demonstrates the level of craftsmanship. Machines can easily create Geneva patterns, but the precise chamfering – especially at the “internal angle” where the two sides intersect – can only be achieved by hand using a file, bit by bit. Top brands like Lange and Patek Philippe have their chamfers done by hand.
How to judge good or bad? The chamfer should be uniform, shiny, and have sharp edges. If the chamfer is blurry, inconsistent in width, or even absent, the polishing grade will drop significantly.
Blue steel screws: The “blue sapphire” in the furnace
The deep blue screws seen through the back cover are the blue steel screws. They are not painted; the steel is heated to approximately 300℃ to form an oxide layer. A slight deviation in temperature control can result in failure.
Blue steel screws are mostly used in high-end movement plates, automatic weights and balance wheel plates. They are often paired with Geneva patterns, fish scale patterns and chamfers, enhancing the visual hierarchy. Before burning the blue color, the screws need to be polished and oil removed. Residual oil stains will cause the oxide layer to be uneven.
Key points for identification: The genuine blue steel screws have a completely blue color for both the screw head and the interior of the one-inch slot. Cheap imitations are painted and then have the slot made, and the slot will reveal a silver-white steel base; the more uniform and pure the color, the better the craftsmanship.
Newbies’ Guide to Avoiding Pitfalls: These Common Mistakes in Polishing Must Be Known
Good finish does not necessarily mean more accurate timekeeping. The accuracy of timekeeping depends on the balance wheel, the hairspring, and the assembly and adjustment. A beautifully finished movement may still have significant timekeeping errors; some movements with almost no decorative finishing can still keep time very accurately.
Patterns do not equal hand-finishing. Modern CNC machines can mass-produce Geneva patterns and fish-scale patterns with high efficiency and low cost. Most mass-produced watches on the market are machine-finished. Hand-finishing is time-consuming and is generally only used in high-end independent watchmaking.
Through-the-back means a good finish. Many brands only polish the exposed automatic rotor beautifully. When the clasp is removed, the bottom is bare and has no decoration, commonly known as “single-sided polishing”. When viewing it, it is best to rotate the watch and look from multiple angles, and do not just focus on the automatic rotor.
Quick Start: Steps for Newbies in On-Site Observation
When you get a transparent wristwatch, don’t try to remember all the terms at once.Just follow this sequence:
Find the light source: Use side light. Direct strong light won’t reveal the details. Soft side light makes it easiest to see the chamfers and textures.
First, look at the edges of the bridge: Check if the sharp corners of the parts have polished slopes.
Then, look at the patterns: Check if the patterns are uniform and if there are any burrs or scratches.
Look at the screws: Check if the edges of the screw slots are polished and if the color of the blue steel screws is natural.
Determine the scope: Is the polishing only done on the automatic rotor or does it cover all the bridges?
Conclusion: The sincerity within a single screw
The process of calibrating the movement is essentially a matter of whether a brand is willing to spend money in the “hidden areas”.
For the average wearer, the calibrating process is merely an enhancement that doesn’t affect the timekeeping. Once you close the back of the watch, no one can see it. But if you start appreciating the beauty of mechanics or consider reselling the watch for its value in the future, then the calibrating process becomes an indispensable criterion.
The next time you pick up a watch with a transparent back, don’t just look at whether it has waves. Instead, focus on the luster of the chamfered edges and the details in the hidden corners – those are the key to determining whether the watch is truly worth it.
