- Rick Lewis
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Most watches offered for sale today are water resistant, from 1 ATM to 30 ATM or more. But few people understand how and why their watches are water resistant, and what they should do to protect their watches. Below are some commonly asked questions about water resistance of a watch.
What makes a watch water-resistant?
There are several features that make a watch water-resistant. The most important is the gaskets, or “0-rings” – usually made of rubber, nylon or Teflon, which form watertight seals at the joints where the crystal, case back, and crown meet the watch case. If the watch is a chronograph, the chronograph pushers will also need to have gaskets.
In addition, water-resistant watch cases are lined with a sealant, applied in the form of a quick-hardening liquid, which helps keep water out.
The thickness and material of the case is also a big factor in determining whether a watch can safely be worn underwater. The case must be sturdy enough to withstand pressure without caving in. This means the case material must be either stainless steel, or titanium. Solid gold cases or stainless cases plated with gold can be water resistant provided they are sufficiently thick.
A screw-in case back, as opposed to one that pushes in, also contributes to a watch’s water resistance.
A screw-in crown, a feature commonly available in divers’ watches, helps prevent water getting into the case through the watch-stem hole. When it is screwed down it forms a water tight seal much like the seal between a jar and its lid.
Why aren’t watches ever labeled or described in advertising as “waterproof” even if they can be worn deep-sea diving?
By definition, waterproof implies that the watch case is impervious to water under all conditions. Watch manufacturers do not and cannot make this claim because under increasing pressure all watch cases will eventually begin to leak. The term “waterproof” was discontinued starting in the late 1960’s. This change was brought about from several government organizations, including the Federal Trade Commission in the USA, who were investigating truthfulness and accuracy of product labeling and advertising.
For example, if a watch is said to be “water resistant” to 100 meters (330 feet), this means that under normal conditions such as swimming, snorkeling, and diving to no more than 100 meters the watch case should not leak.
Because the Federal Trade Commission of the US issued guidelines prohibiting the use of the term “waterproof” to describe watches, including deep-sea diving watches, the proper term is “water-resistant.” Therefore, before you make a water-resistant watch via your watch manufacturer, become familiar with the different levels of water resistance and the limitations of water-resistant watches to ensure you make a watch suitable for your market.
My watch is labeled “water-resistant to 50 meters” but the manufacturer’s instructions say I can only wear it swimming, not snorkeling or diving. Why is that?
The different levels of water resistance as expressed in meters are only theoretical. They refer to the depth at which the watch will keep out water if both watch and the water are perfectly motionless, says Scott Chou, technical director at Seiko Corp. of America. These conditions, of course, are never met in the real swimmer’s or diver’s world. In real life, the movement of the wearer’s arm through the water dramatically adds the pressure on the watch as well, so it is advised that, to be safe, the watch should be worn to the depths less than what is indicated by lab testing machines.
What are the various levels of water-resistance?
Watches with the lowest level of water resistance are labeled simply “water-resistant.” They can withstand splashes of water but should not be submerged.
The following usage recommendations are suggested by industry standards.
- Water-resistant to 30 meters (100 feet): Watches with this rating will withstand splashes of water or rain but should not be worn while swimming or diving.
- Water-resistant to 50 meters (165 feet): Watches with this rating are suitable for showering or swimming in shallow water.
- Water-resistant to 100 meters (330 feet): Watches with this rating are suitable for swimming and snorkeling.
- Water-resistant to 150 meters (500 feet): Watches with this rating are suitable for snorkeling.
- Water-resistant to 200 meters (660 feet): Watches with this rating are suitable for skin diving.
- Diver’s 150 meters (500 feet). Meets ISO standards and is suitable for scuba diving.
- Diver’s 200 meters (660 feet). Meets ISO standards and is suitable for scuba diving.
Please note that we do not recommend swimming or diving with your watch unless it has a screw-down crown (also known as screw-lock or screw-in crown) and is water-resistant to at least 100 meters.
Keep in mind that the depth specified on the watch dial or caseback represents the results of tests done in the lab, not in the ocean! And, water resistance is tested in measurements of atmosphere (ATM). Each ATM denotes 10 meters of static water pressure.
If you want to make a watch suitable for snorkeling or deep sea diving, then you will need to have a screw-down crown and a screw-down case back. The water resistance required for these dive watches will be at least 20 ATM (200 meters/660 feet).
I’ve seen the abbreviation ATM used in labeling degrees of water resistance. What does it mean?
It stands for “atmosphere” and it’s equal to 10 meters of static water pressure. Another word for “atmosphere” is “bar,” which is often used in Europe.
Is water resistance permanent?
No. Just like things in real life, nothing is permanent. Water resistance depends on several factors (as mentioned above), some of which can be affected by wear or simply by time. Over time, gaskets can become corroded or misshapen, cases denied or crystals loose or broken. That’s why your watch, like your car and your teeth, needs preventive maintenance.
Obviously, there are misconceptions about water resistance. Lots of people assume the water-resistance level of a watch represents the watch’s true water resistance when in reality it does not. As mentioned in answers to questions above, this is because its water-resistance level is based on a motionless depth test, not in a turbulent ocean. The depth level indicated on the watch dial or caseback does not contemplate sudden changes in depth, nor does it take into account temperature changes. Water-resistant watches can also experience water damage if the owner descends underwater too quickly, or if the watch is removed from cold water into warmer air. Both consumers and retailers should note that these watches do not remain water-resistant for their entire lifetimes, as their water resistance will naturally decrease with time, to be honest and realistic.
How should I care for a water resistant watch?
First, it is not recommended to wear your water resistant watch in a hot shower, sauna or hot tub, even though the watch is tested to have the required water resistance. Many people actually don’t understand the nature / properties of metal, and complain blindly to manufacturers or retailers when there is a water resistance problem with their watch. They don’t realize that the extreme heat can cause the metal parts to expand at a different rate than the rubber gaskets. This creates small openings that can allow water droplets to penetrate the watch. Sudden temperature changes are especially harsh. Take care not to jump into a cold pool after wearing your watch in the hot tub.
After swimming or diving in salt water, immediately rinse the watch in a stream of fresh water. If your watch has a rotating bezel, turn the bezel several times while rinsing it. This will prevent salt buildup and corrosion of the bezel ring.
Some chemicals can corrode the gaskets and make it vulnerable. Heavily chlorinated water can cause problems, as can spray-on perfumes and hairsprays that work their way into the watch’s seams and damage the gaskets. (They can also damage your watch’s finish.)
Also, while the watch is submerged in water or still wet, you must NOT press the buttons / pushers on the watch You must not pull out the crown while the watch is submerged in water. If the case, glass or seal is damaged in any way the watch will no longer be guaranteed water-resistant. Condensation can appear in any watch and is caused by a sudden change in temperature, i.e. When a watch is removed from a cold room and placed into a warm room, or vice versa. The appearance of condensation does not mean the watch will not operate properly, but to be safe it should be serviced by a qualified repairman. Batteries in water-resistant watches should be replaced by a professional so that the seal can be checked and renewed if necessary, otherwise the watch may no longer be guaranteed water-resistant. (Speaking of battery, it is good practice to change the battery hatch or caseback gaskets whenever the battery is changed.)
As mentioned above, water-resistance is not a permanent condition. For example, the gaskets that are around the stem, caseback and glass can deteriorate with time and should be inspected and changed periodically by a professional.
Leather straps can be made to be water resistant too. Generally, however, leather straps are more easily damaged by frequent exposure to water. So if you are going to wear your watch while swimming — think of making / buying a watch with a metal bracelet or a rubber or nylon diver strap.
How often does water resistance need to be checked?
At least once a year. Like most manufacturers, we suggest that water resistance needs to be tested every time the case back is opened, because opening the case can dislodge the gaskets. This is why unauthorized openingof the watch caseback is usually not recommended, because doing will invalidate your warranty rights. This rule applies even to a simple battery change done by a unqualified person. (For your information, some service centers may change the gaskets when you take the watch to a qualified technician for service.)
ADVICE: To maintain the integrity of the watch, watch owners should have the watch serviced and tested by a professional annually.
How is water resistance tested?
There are basically two ways of machine-testing water resistance, referred to as “dry” and “wet” testing. In the former, the watch is subjected to air pressure and measurements taken to see whether the case expands as a result of air leaking into the case. If it does, the watch is not water resistant.
In one type of “wet” testing, the watch is first subjected to air pressure, then submerged in water. If air bubbles come out of the watch when it is underwater, it means air seeped into the watch before it was submerged, and it is therefore not water-resistant. In another type, the watch is placed in a small water-filled chamber which is then subjected to pressure from a piston. If water gets into the watch, it’s not water resistant.
Can I wear my water resistant watch in the hot tub?
No. As said above, exposing your watch to heat, whether it’s in a hot tub or sauna, can cause the gaskets to warp and lose their shape and their ability to keep out water.
Likewise, sudden changes of temperature experienced going from, for instance, a hot tub (100º F) to a cold swimming pool (70º F) can cause a contraction of the rubber seals in a watch–which may allow water to leak in.
Besides extreme temperatures, what will jeopardize a watch’s water-resistance?
As mentioned above, some chemicals can corrode the gaskets and make it vulnerable. Heavily chlorinated water can cause problems as well, as can spray-on perfumes and hair sprays that work their way into the watch’s seams and damage the gaskets. (They can also damage a watch’s finish.)
My divers’ watch came with a leather strap. Will the water harm it?
It may. Wearing a leather strap in the pool or diving is generally not recommended, says TAG Heuer’s John Sokol. “It’s like wearing your shoes to go swimming.” Instead, choose a metal, plastic or nylon strap, he advises.