If you’ve seen a number of fine Swiss watches, then you’ve probably encountered a movement that integrates blue screws. So why do some watches have these while others of similar distinction don’t?
The blue screws are actually more for aesthetic reasons than for functionality. Although it is possible to use chemicals to make the screws colored blue, a proper method is costly and time-consuming.
The British Horological Institute provides information on how the process is completed:
- To make the screw head blue, it is first critical to clean, polish, and remove any residue from its surface.
- Hold the screw by the thread in a lathe or pin vice. Then it can be cleaned with a hacksaw or piercing saw.
- Polish the screw head using a crocus paper. Use a flexible sheet or cork to support it.
- When the head is polished, wash it in alcohol or any other type of volatile solvent.
- Hold it by the threaded end using a plier to pass it through a spirit lamp flame. At the beginning a straw color will emerge until it will become a deep purple.
- Once the color turns into the type of blue you want, immediately place the screw in water before rinsing it again on the solvent.