What Can Damage An Automatic Watch?

The risks at a glance

1. Magnetism — the most common and the least suspected

A hairspring is a fine steel coil, and a magnetized hairspring has its coils cling to each other, which shortens its effective length and makes the watch run fast— sometimes by tens of seconds a day, sometimes enough to stop it. It is almost certainly the single most common cause of an affordable automatic "going wrong".

The culprits are not exotic. Laptop and tablet speakers, the magnetic clasps on laptop sleeves and tablet covers, magnetic phone mounts, handbag and jacket closures, and the magnetic strip on some tool belts. Any of them is strong enough if the watch sits against it, and the watches here carry no antimagnetic specification to appeal to.

The good news: it is completely reversible. A watchmaker demagnetizes a watch in seconds, and it is one of the cheapest jobs in the trade. Do not conclude that your watch needs regulating until it has been demagnetized — why is my automatic watch losing time runs the full diagnosis.

2. Heat plus water — worse than cold water at depth

This is the one that catches people out, because the number on the dial looks generous. A water-resistance rating is a static pressure test at room temperature, not a promise about hot water. Heat expands the case and the gaskets at different rates, and a cooling case draws air — and moisture — inward past a gasket that has temporarily lost its seal.

Which means a hot shower, a sauna, a hot tub or washing up in hot water is harder on a watch than swimming a length of a cold pool. On anything rated 30m or 50m — most dress watches, including several on this site — it is the fastest route to moisture under the crystal. Water resistance ratings explained has the full table of what each rating permits.

3. Setting the date in the forbidden window

Between roughly 8pm and 4am the calendar mechanism is already engaged, slowly advancing toward the midnight change. Forcing the date wheel by hand while those levers are under load is how the date-change mechanism gets damaged — and it is a repair, not an adjustment. Orient states this explicitly for its own calibers, and the rule applies across the board.

The safe procedure: if you need to set the date, first move the hands to roughly 6 o'clock so the mechanism is well clear, then set the date, then set the time. Full sequence in how to set an automatic watch. On a day-date watch the same caution applies to both wheels — the 80-hour picks and day-date picks are the two groups where this comes up most, because they are the watches you set least often.

4. An unscrewed crown

If your watch has a screw-down crown, its water-resistance rating is void while the crown is out. The usual sequence is: unscrew it to hand-wind the watch, set the time, get distracted, put the watch on, wash your hands. A 200m diver with an unscrewed crown is less water resistant than a 30m dress watch with a sealed one.

Make screwing it back down the last step of every interaction with the crown, and check it with a fingernail. This is also why the water-resistance rating is a useful durability proxy for a work watch — the hardware that earns the rating is the same hardware that keeps dust and sweat out. See best automatic watches for work.

5. Skipping the service for a decade

Lubricants degrade whether or not the watch is worn. A movement running on dry or tacky oil wears its own pivots, and the longer it goes the more of the damage becomes permanent rather than cleanable. This is slow, invisible and the most expensive item on this list.

The honest caveat this site always adds: on an affordable automatic a full service can approach or exceed what the watch cost, so for many owners the rational plan is to wear it until it stops and replace it. That is a legitimate decision rather than neglect — the arithmetic is in automatic watch service cost and how long do automatic watches last.

6. Ultrasonic cleaners, compressed air and solvents

• Ultrasonic jewelry cleaners. Fine for a steel bracelet off the watch. Not for a cased watch: ultrasonic energy is exactly the kind of sustained high-frequency vibration a balance and hairspring are not designed to absorb, and the fluid will find any gasket that is past its best.
• Compressed air. Blowing a jet of air at a caseback or a crown gap pushes dust and moisture in.
• Solvents, acetone and alcohol wipes. They attack gaskets and the adhesives holding dial markers and crystal gaskets. Clean a watch with a damp microfibre cloth and nothing else.
• Sunscreen, insect repellent and perfume on a leather strap. These destroy leather quickly and discolor it permanently. On a beach holiday, wear the watch on nylon or rubber and keep the leather at home — changing a strap takes five minutes.

7. Sustained vibration from power tools

Occasional knocks are what shock protection is for. Hours of jackhammer, impact wrench, demolition saw or angle grinder is a different load, and no maker publishes a tolerance for it — anyone who gives you a number is inventing one. If that is your working day, wear quartz and keep the mechanical watch for afterwards. The honest version of that argument, with a $70 recommendation attached, is in best automatic watches for work.

Five things that damage nothing

Worth saying plainly, because each of these comes up constantly:

• Letting it stop. A stopped automatic is not harmed in any way. Wind it or wear it and it runs. Why it stops.
• Hand-winding it. You cannot overwind an automatic — the mainspring is held by a slipping clutch. The full explanation.
• Airport security. Walk-through arches and X-ray belts are not the kind of sustained static magnetic field that magnetizes a hairspring, and X-rays do nothing to a mechanical movement.
• Wearing it every day. Daily wear is what an automatic is for, and a watch kept fully wound by being worn actually keeps better time than one run down. The case for it.
• Rain and hand-washing. Fine on anything rated 30m or better. It is heat and pressure that matter, not water as such.

If you want a watch that forgives more of this

Three specifications do most of the protecting: a sapphire crystal for abrasion, 200m of water resistance(read as a seal rating, which means thicker gaskets and a screw-down crown) and a published caliber you can actually get serviced. The picks below are the registry's best combinations of those three.