June 1999

Timepieces:News

Explaining Water Resistance

Know the terms before you test or repair. Your customer will appreciate it

By David Christianson
Certified Master Watchmaker

When customers ask about "waterproof" watches, perhaps a quick lesson in terminology is in order. If you can explain the terms related to water resistance in timepieces, you'll add to your credibility and your ability to retain customers. First, explain to customers "water resistance" – not "waterproof" – is the correct term to use. The Federal Trade Commission Guides are clear on what terms to use and what they mean. Here's are some guidelines on the main categories: non-water resistant cases, water resistant cases and diver cases.

Non-Water Resistant Cases
These are mostly dress watches made with thin gaskets that provide only minimal moisture protection. Some do include plastic or metal shields around the stem to prevent dust from entering. But water will penetrate.

Identification: If there's no mention of water resistance anywhere on the back of the case, it's not water resistant.

Use limits: These cases will resist everyday dust, humid August days or an accidental splatter in the kitchen sink. But avoid prolonged exposure to steam from boiling water while cooking or any extended full water exposure. No swimming or bathing while wearing the watch.

Water-Resistant Cases
Identification: The case or dial will say "water resistant" for the minimum classification. When this is accompanied by a number, it indicates the depth below sea level and accompanying pressure the watch can withstand when new. Look for an ATM (atmospheres) marking or the term "water resistant" combined with a figure of, say, 50 meters (5 ATM). For customers unaccustomed to the metric system, multiply the number of meters by 3.3 to get feet (50 meters X 3.3 = 165 feet). The rating is determined by a testing device when all the gaskets are fresh.

Use Limits (see table at bottom): Because a person doesn't normally replace or test the watch gasket annually, recommend buying a watch rated to withstand the most extreme condition the wearer will likely encounter.

Frequent swimmers may consider at least a 100-meter watch; casual swimmers may do fine with a 50-meter watch.

Frequent use during sports would likely require at least a 100-meter rating to keep out perspiration.

Professional Diver Case
Identification: These cases are rated at 300 meters or greater and have heavy gaskets and crystals intended for use at scuba depths.

Use Limits: Few. If your customer is a serious diver, suggest he or she bring the watch in for an annual pressure test and/or gasket replacement to be sure the heavy gaskets are tight and don't leak.

General Precautions
With any water-resistant watch, remind customers not to operate the crown or push buttons while underwater. Also remind them to dry the case before setting the watch.

If the crown is a screw-down or locking type, tell them to be sure it's in place before diving or swimming. Also note that chemical solvents can penetrate many water-resistant cases. If these are nearby, they may affect the water resistance of the watch.

Next month: Checking water damage.

David A. Christianson owns Christianson Jewelry, Kendallville, IN, and is president of the American Watchmakers-Clockmakers Institute, a certified master watchmaker and a fellow of the British Horological Society. He discusses watch repair for the sales staff in this column each month. Please send questions, suggestions and comments toProfessional Jeweler,1500 Walnut St., Suite 1200, Philadelphia, PA 19102; askus@professionaljeweler.com.

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