A mechanical watch is powered by a spiral spring, which accumulates elastic energy, and releases it gradually and constantly, operating the hands and giving back the measure of time. To keep the watch working, the mainspring must always be wound. It can be wound manually, in which case it is a manual wound movement, or through a system that employs moving the watch while it is being worn, in which case we are referring to a self-winding movement or automatic.

Manual winding: The mainspring is wound manually by turning the crown at least once per day. This requires no additional action on our part and guarantees us an accurate reading of time.

Automatic winding: This type of movement winds itself through oscillations made by the wrist when we wear our watch. It is therefore not necessary to rewind it daily as we do with manual movements.

All automatic watches feature a rotor, also called an oscillating weight or mass. Thanks to the movement of the wrist, the weight swings in a circle, which winds the watch. Typically, the rotor is located on the back of the watch movement. There are three main types of rotors in automatic watches including traditional rotors, micro-rotors, and peripheral rotors.

The most common type of rotor in automatic watches is a semi-circular weight, usually made of gold or platinum. It’s mounted to the center of the watch movement and partially covers the movement. Consider it to be the “final layer” in a watch movement. Many watch brands decorate the rotor using métiers d’art, including guilloché and engraving. The oscillating mass of an automatic watch is often made of gold, platinum, or tungsten carbide.

All RESERVOIR watches is featured with an oscillating mass.