Having a wristwatch be watertight and be accurate go hand-in-hand. Rolex founder Hans Wilsdorf was an early pioneer in the development and distribution of wristwatches. Society at the turn of the 20th Century thought smaller wristwatches could not be as accurate as the more gentlemanly pocket watches. Wilsdorf realized that in order to keep a wristwatch accurate, it also needed to be waterproof and self-winding.
Rolex as well as other manufacturers in the wristwatch industry played around with external hermitically sealed cases that protected the wrist watch from the elements; essentially there was a secondary case around the main watch case. Wilsdorf found an external watch case cumbersome as the watch still required removal from the case to wind, and set the watch. Fast forward to the mid to late 1920’s when Rolex developed both automatically winding movements, and waterproof cases and crowns, the idea of a waterproof watch became reality. A waterproof watch kept out not only water, but also dust and dirt that affected the movement’s reliability. Rolex’s perpetually winding movement, and the development of the Oyster case with screwdown caseback and winding crown made Rolex the industry leader in human-proof and accurate wristwatches.
With the exception of the Rolex Cellini series, all Rolex wristwatches are designed to handle water pressure to a minimum of 100 meters or 328 feet. Rolex diving watches are rated upwards of 4000 meters or 12,000 feet – a depth well beyond what is survivable by any human being. Rolex considers these depth designations conservative as their watches are designed to withstand 25% greater than specified.
Rolex has conservative water resistance designations because of the difference between static versus dynamic water pressure. Water resistance ratings are based on a laboratory pressure tests comparable to a swimmer or diver sitting still at that pressure level, but many water-based activities involve movement and other environmental changes. These are exceptions to how the watch was rated may challenge or defeat the water protection. A watch for a jet or water skier requires a higher rating because of the increased pressure when the watch hits the water for speed. The same is true for watches used in the bathtub with little dynamic pressure; a watch in this setting can use a lower water resistance rating.
Rolex achieves their water ratings through the use of a solid Oyster case, a screwdown casebacks that compresses a Zytel gasket, and a screwdown crown that contains two Zytel gaskets for a Twinloc crown, or four Zytel gaskets on the higher rated Triploc crown. The sapphire crystal is pressed onto the Oyster case with a Delrin gasket that holds the crystal in a water tight seal. Technically, the watch is waterproof, but the Federal Trade Commission discontinued the term “waterproof” in the late 1960’s because the commission felt that “waterproof” misrepresented products that used the designation.
Couple Of Things to Check
Both Zytel and Delrin deteriorate and lose their elasticity over time. These gaskets do their job when water pressure compresses them and a dry gasket will fail. Even though your Rolex defies water to a specific rating, your watch should be pressure tested every year or so. Checking the integrity of the watch seals can be done by a simple pressure test that any Rolex dealer, including Fourtané can
do for you to insure that water stays out of the watchcase. The other item to check to insure that the watchcase is water tight is obvious, but many people forget to check, is verifying that the winding crown is screwed down snugly before entering the ocean or the swimming pool. The crown needs to be snug and not move on its own, -not as tight as an automobile lug nut.
Without question, your Rolex defies water, and with care will continue to do so for many years.