The caseback is the element of the watch case that serves to protect the movement, dial, and hands from external damage (dust, humidity, etc.). Various attachment methods exist for the caseback.

  • It can be pressure-fitted, creating tension between the middle part’s fitting diameter and the caseback’s.
  • The commonly used method today involves fixing the caseback to the middle part with four or more screws. Elegant and easy to manufacture, this method provides very good water resistance.
  • Sometimes, the screws pass through the middle part and attach to the bezel. Water resistance is even better with the middle part thus “sandwiched” between the caseback and the bezel.
  • Finally, threading can be applied to the caseback’s outer diameter and tapping to the middle part’s inner diameter. In this case, the caseback itself acts as a screw to close the case. This construction is particularly effective in terms of water resistance and is typical for diving, sports, and technical watches.

Historically, pocket watches had two superimposed casebacks. One was press-fitted to the middle part or soldered to it. Until 1830, watches did not have a crown. Winding and setting the time were done using a key (similar to a clock). This square-shaped key acted directly on the barrel‘s arbor (winding) or on an extension of the centre wheel pivot (time-setting). To allow the key to access these two elements, two holes were pierced through the first caseback. Even though the watches were not waterproof at that time, such openings were not acceptable for keeping dust and moisture out of the watch case. A second caseback (or cover) was connected to the first by a hinge and closed with a slight press. Opening it by rotating the upper lid, provided access to the key holes for winding and setting the watch.

In the era of pocket watches, the caseback (especially the outer one) was, along with the dial, the favoured canvas for artisans and artists. Engraving, enamelling, or a combination of both were commonly used. Decoration with precious stones was less common, but casebacks, like bezels, were sometimes set with half pearls or mother-of-pearl marquetry in the 18th and 19th centuries.

Artistic decoration has regained popularity today. This enthusiasm helps perpetuate techniques and knowledge that seemed destined to be lost at the end of the 20th century.

With the wristwatch, the caseback has become the preferred place for informative inscriptions (engraving, printing, metallization, etc.) on the watch. Information such as the brand name and/or model, the reference, its individual number (limited or not), and its water resistance can be found on the caseback.

Traditionally, watch casebacks were solid and in the form of a disk. However, since the early 19th century, casebacks have sometimes been a bezel with a fixed crystal in the centre to see the movement. Although sporadical until the end of the 20th century, this practice has since become more widespread.

The evolution of the caseback is going on. Nowadays, some brands embed in the caseback an electronic chip that requires no power source. An external scanner can read the chip and get information about the history of the watch, and its service record, or simply authenticate it.

Depending on its design or technical specifications (water resistance, function, etc.), the caseback of a watch may require feats of ingenuity and craftsmanship. However, the caseback is often relatively simple to manufacture and does not require extensive resources. A bench lathe may suffice in many cases to manufacture a round-shaped caseback, while a milling machine will be used to create casebacks of various shapes (square, barrel, etc.).

A caseback manufactured using the artisanal method often deserves hand engraving (indicative or decorative), but a mechanical engraving can also be considered an artisanal process here.

Semi-artisanal production is characterized by small series. Similar to industrial methods, machining centers (CNC) are already predominantly used for such production volumes. What mainly differentiates the two caseback production methods is the finishing and decoration stages.

For small series of watches at a certain price level, hand engraving of the caseback is still often preferred over mechanical or chemical engraving. And the placement of stones for setting is done by hand rather than by machine.

Industrially, the use of machining centers (CNC) is often the most appropriate and therefore the most common way to produce casebacks. Often, a single machine is sufficient to perform all the manufacturing steps. Furthermore, this same machine can often carry out the engraving and decoration and finishing stages at a high quality level for industrially produced watches. Many industrial processes can, in some cases, complement the work of machining centers (laser engraving, metallization, surface treatments, etc.).

Here again, cutting-edge technologies distinguish themselves from artisanal, semi-artisanal, and industrial methods primarily through the materials used rather than production volumes. Injection moulding and sintering are mainly used to shape materials such as plastics, composites, and ceramics, although common machining and/or polishing operations are sometimes necessary afterwards. The manufacturing process for sapphire cases (synthetic corundum and its derivatives) resembles the industrial method, which includes machining and polishing. However, the hardness of sapphire requires the use of high-tech machines and tools.