Featured Image © Joshua Clare-Flagg, WIAA
[5min read time]
In addition to the fact that the crown can be a beautiful design element of a watch, it is the link between the inside of a watch, i.e. the movement, and the outside world. It basically has two functions for mechanical watches; Set the time / date / day and manually wind the movement. In addition to the case back and glass, the crown is also one of the critical points where water can enter. In fact, it is often the point at which this happens, because only the crown is used regularly and is therefore subject to more mechanical wear and tear than the other openings. Tinkerers and watch manufacturers have come up with a number of solutions to provide a secure seal of the crown. Two of them have prevailed; the screw-down crown, and the push/pull crown. What are the differences and which crown is the right one or you?
First of all, consider that both a screw-down and push/pull crown is not guaranteed waterproof when set to the open position. "Open" means that it is in the position where the time / date / day can be set. If you forget to screw down or push in the crown, water can enter.
A conventional crown can be moved freely and is sealed with O-rings. All manufacturers also lubricate the sealing rings with silicone oil or grease in order to minimize friction during use. Pull/push crowns seal a watch securely up to 200 meters and more - so they are not less waterproof than a screw-down crown. In contrary, the thread does not wear out, meaning that a Pull/push crown, in theory will stay waterproof longer than a Screw-down crown.
Advantages and disadvantages of a Push/pull crown:
+ is waterproof in the pushed-in crown position (Formex Watches are periodically tested with crown in the pulled position to the full depth)
+ can be manually wound at any time in the pushed-in crown position
+ Time / day / date can be set with just one pull
- if you forget to push the crown in before using in water, water can enter the movement
- If the crown gets tangled under water and pops out, water enters the movement
The concept of the screw-down crown was not invented by Rolex, but was first used by Rolex in 1926 in an Oyster case. Hans Wilsdorf, the Rolex owner, actually bought the idea from the two inventors Georges Peret and Paul Perregaux. On October 18, 1926, the screw-down crown was legally protected by Rolex. To date, the concept is the most widespread crown protection against water. The principle is simple: the tube of the watch ends in a screw thread, the counterpart of which is located on the inside of the crown. Here too, O-rings are used for sealing, with only one difference. In the screwed state, one of the rings is pressed against the tube. With diving watches, this serves an essential function - which hardly anyone is aware of and which has nothing to do with water resistance: a screw-down crown cannot be operated accidentally. Underwater, correct observance of decompression and diving times is essential for survival. A wrong time indication could be fatal. For a watch that is not used for professional diving with an oxygen bottle, however, a screw-down crown could be regarded as overkill. In addition to that, some owners tend to exaggerate a little when screwing down the crown and do so with more torque than is required, which can damage the seals and the thread.
Advantages and disadvantages of a screw-down crown:
+ is waterproof when in the screwed-down position
+ cannot be operated accidentally
- The crown must be unscrewed each time for manual winding or to adjust time / date / day
- if you forget to screw-down the crown before using water, water can enter the movement