Service facts about fine watches

Service intervals
Water resistance

Service intervals

Isn't it amazing that everyone knows the difference between the carburetor and exhaust pipe of an automobile, yet almost no one outside the watch industry knows the functioning of a watch, or even the names of the major parts that make it go? Yet the watch is much more of a daily companion than a car. The watch is as essential to the modern man as food and drink. Quite astounding when you think about it, isn't it?

It takes thousands of human hands to make the plates and bridges, to drill, countersink, and thread the holes and recesses, to perfect and deburr the surfaces, to grind and pivot the pinions, to turn, cup, olive and mirror polish the microscopic jewels, and to make and finish the train, the dial, the hands, and the case. Many fine watch companies even polish, by hand, every wheel, gear, pinion, and cog until a watch is virtually frictionless.

In spite of the advice manufacturers give, however, few of their customers take the precaution of having their watches periodically overhauled (cleaned and oiled). Periodic service will prevent the conditions that invariably cause a watch to run irregularly or even to stop -- the normal wear of parts that are subject to extremely heavy mechanical stresses, the presence of dust, and changes that affect oils when they become stale.

When a watch is overhauled at our workshop, it is completely disassembled and each of its parts is placed in special chemical solutions that dissolve dirt, dust, and that emulsify any dried out oils. When the watch is reassembled, special oils are applied to lubricate all essential parts.

We recommend that a general overhaul be performed every three years and that all water-resistant watches be tested once a year for case tightness.


In the US Naval Observatory in Washington, DC there are several Riefler Clocks that were built and installed at great expense. These clocks were mounted on concrete piers sunk deep into the earth to avoid vibration. They are housed in a room that is always kept at the same temperature. Every twenty-eight seconds they are automatically wound by electricity. They run in a vacuum. Yet, in spite of all the precautions that human ingenuity can devise, these mechanical clocks don't keep perfect time. Only the fixed stars, nature's own time keepers, are absolutely accurate. Through nightly observations of the stars, corrections are made in these Riefler Clocks so that the nation might have its time as correct as humanly possible.*

The public, ordinarily unaware that the keeping of perfect time is a mechanical impossibility, shouldn't expect absolute accuracy in a watch. Bumped and rattled about, subject to extreme variations in temperature and position, wound at any time or not at all, sometimes allowed to run with the accumulated dirt of years and the absence of any trace of oil, a watch that keeps approximately good time is indeed a marvelous machine.

Many watches, even the most expensive ones, aren't equipped with a "stop hack" to stop the watch when the crown is pulled to set the time. As a result, it's difficult to synchronize these watches to the exact time with a time signal, such as the Naval Observatory's Master Clock.

In 24 hours, the escapement of a mechanical watch pushes the gears 432,000 times. Since a day has 86,400 seconds, even a watch that runs five minutes fast or slow each day has an accuracy of over 99.6 percent! A finer mechanical watch that gains or loses about nine seconds a day or about a minute a week has a breathtaking precision of over 99.99 per cent. This is very high precision, given the fact that the movement is constantly affected by the earth's gravity, metal expansion and contraction, temperature variations, subtle changes in lubrication and friction, shocks, and so on.

*The US Naval Observatory's Riefler clocks have been supplanted for several decades by atomic clocks, which are now used to set the nation's time.

Water resistance

Few mechanical devices are more vulnerable to accidents than wrist watches. They face three major and persistent hazards: shocks and jarring, water and moisture, and fine dust. The temperature variations to which wrist watches are inevitably subjected induce exchanges between the inside of the case and the atmosphere around it. This circulation causes dust particles and moisture to be sucked into the case and gradually foul and damage the watch movement or mechanism. The only satisfactory way of keeping water and moisture out of a watch is to use a totally watertight case.

Standards set by the US Federal Trade Commission and the Swiss Normes de l'Industrie Hologere Suisse define a water-resistant watch as one designed for daily use that must not admit water in the course of activities such as swimming. It should be also be operational despite substantial atmospheric and temperature variations.

Water-resistant watches must be able to withstand pressure equivalent to a depth of 20 meters (66 feet) below water. Such watches are safe in or around a pool or beach. However, while this is more than enough water resistance for everyday life, even the finest water-resistant watches should never be used for skindiving.

A water-resistant watch and a waterproof divers watch are emphatically not the same thing! The latter is designed for skindiving, a demanding and occasionally dangerous activity in which being able to read the correct time to the exact minute can make the difference between life and death. For example, a special divers watch, considered virtually waterproof, is made by IWC and known as the Porsche Design Ocean 2000. This is a titanium watch developed for the West German Navy to be waterproof at a mind-boggling ocean depth of 2,000 meters (6,600 feet). The sealing construction of this watch is unique. The crown threads tightly to its shaft sleeve and three pressure barriers definitively keep the movement sealed in any environment.

Checking Water Resistance. The most common failure of a watch to be water resistant is caused by a faulty contact between the case at an opening around the glass, crown, or pushbutton and the opening's gasket. Worn or defective rubber O-rings are often a cause of failure. Condensation forming under the crystal of a watch following a sharp temperature change (a swim after a stretch in the sun, for example) tells you to have the watch checked without delay. This can be an indication of additional moisture elsewhere inside the case. It is also the only water-tightness check a consumer can perform.

Of course non-water-resistant watches don't contain the additional seals and gaskets found on water-resistant models. Consequently, moisture-laden air can easily enter the case. Once inside, a pronounced change in temperature may cause condensation to form under the crystal. Very little can be done to prevent this. A high-quality water-resistant watch, however, properly serviced and maintained, will be sealed to prevent internal water damage and will more than outlast an ordinary watch.

Proper Maintenance. At our service center, after closing a water-resistant watch, we check it with our most sophisticated testing equipment to simulate underwater pressure conditions. To keep the watch properly sealed, we replace any defective parts we find, such as gaskets, crystals, and crowns. Water-resistant watches should be tested for case tightness at least once a year, as well as every time the watch is opened, such as when a battery is replaced.

Click here to learn how we test your watch for water resistance

Page last modified 02/06/24

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Superior Watch Service Inc.   

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Tel: (718) 851-5306

Official Authorized Factory Service for
IWC-Schaffhausen, Porsche Design by IWC, Porsche Design by Orfina