Heat tempered hands

May 04, 2020

Very few watch companies make their own hands. Not long after starting work on ours, we began to realise why! To give you an idea of how we make them, it’s probably useful to first explain how hands are normally made and how they affix to the movement.

Aluminium (at the lower end) or brass (at the mid-to-high end) is used for the base material before being coated in another substance such as nickel for a silver-look, or chemically treated to give a ‘blued’ look. Each hand is stamped out of a long thin sheet of brass or aluminium using a die (a cookie cutter!) and a hydraulic press. This process cuts the hand out, curves it if required, and creates a hole. Around this opening the material forms into a very shallow tube which attaches to the hands by friction to the respective hour/minute/second pipe from the movement.

To create thermally blued hands, we need to use a particular type of high-carbon steel. Whilst brass is a relatively malleable metal, steel is not, and so it won’t press-fit onto the movement. To get around this we make the hands in steel and then create a ‘pipe’ for each one out of brass. These pipes are tiny, especially for the second hand, and each needs to be fixed to the steel hand before it’s affixed to the movement. To do this the pipe is made on a lathe with a miniscule chamfer in the top so that when it’s placed inside the steel hole in the hand it deforms evenly when struck with a hammer. Now that the pipe and hand are one, they can be attached to the watch. 

Thermal blueing involves heating the hands on a bed of brass filings (so that the heat is evenly dissipated) until the required colour is achieved in the spectrum. Getting an even finish is the main challenge here, and it takes quite a bit of practice and skill to get it right.

The steel goes through a range of colours before reaching the familiar deep blue, and we thought the goldy/straw hue worked well with some of our darker dials. Fixing on a colour along the spectrum, and doing it evenly throughout is more challenging than blueing as the colour is only there for a fleeting second under heat - probably why it’s rarely seen in watchmaking.