⚡ Key Takeaways
- → Most important habit: screw the crown down before ANY water exposure — every time
- → Rinse with fresh water after saltwater · dry completely · pay attention to crown and bracelet links
- → NH35 automatic → service every 3-5 years · $50-150 at a qualified watchmaker
- → VK64 meca-quartz → battery every 3 years · SR927W · $5-15 · watch for 2-second jumps
- → Never press chronograph pushers underwater · never wear in sauna or steam room
- → Sapphire crystal → scratch resistant · microfibre cloth only · no special care needed
📋 In This Guide
After 12 years of building custom watches and handling thousands of warranty claims and support queries, I can tell you exactly how to care for a watch — and exactly which mistakes shorten its life.
Most watch buyers never read a care guide. They unbox the watch, put it on, and hope for the best. For watches with sapphire crystal and quality movements, this approach works reasonably well. For watches with mineral glass and unknown movements, it does not. But even quality watches benefit significantly from a small amount of informed daily care — and are damaged significantly by a small number of common mistakes.
This guide covers everything you need to know about caring for a custom watch in daily use — from the daily habits that extend its life to the specific mistakes that end warranties and damage movements. Whether you own one of our watches or any quality timepiece, these principles apply.
Daily Care: The Habits That Matter
Screw the Crown Down Before Water Exposure
This is the single most important habitual action in watch care — and the one most buyers forget most often. A screw-down crown on a water-resistant watch provides dramatically more protection than a push-pull crown — but only if it is actually screwed down before water contact.
A crown that is unscrewed but still pushed in provides minimal resistance to water entry. Water can work its way through the crown tube under pressure, particularly in swimming or shower use. A crown that is fully threaded into the case creates a sealed barrier that dramatically reduces this risk.
The habit to build: before any water exposure — swimming, showering, washing hands — check that the crown is fully screwed in. It takes two seconds. It is the difference between a watch that handles water correctly and one that fails its water resistance rating at the worst possible moment.
"I swam with the Milsub for six months before I realised I had not been screwing the crown down fully — I was pushing it in but not threading it. The watch survived because the 200-metre case construction has margin. But Kevin's response to my question made me change the habit permanently. Two seconds before any water exposure. That is all it takes. I have not had a moment's concern since."
— Robert P. · San Diego, CA · ✓ Verified buyer · Green Milsub Vintage Mod Watch
Rinse After Saltwater Exposure
Saltwater is corrosive. It accelerates the degradation of gaskets, attacks steel case components, and can accumulate in bracelet links and crown tubes where it continues to cause damage after the watch has been removed from the water.
After any sea swimming or saltwater exposure, rinse the watch thoroughly under fresh running water. Pay particular attention to the crown area, the bracelet links, and the caseback edge. Allow the watch to dry completely before storage. This simple habit extends the water resistance reliability of any watch significantly.
Avoid Strong Magnetic Fields
Automatic movements — and to a lesser extent meca-quartz movements — are affected by strong magnetic fields. The hairspring in an automatic movement can become magnetised, causing it to stick together and dramatically affecting accuracy. A magnetised NH35 can lose or gain minutes per day rather than seconds.
Common sources of strong magnetic fields in daily life: laptop computers, tablet computers, smartphones placed face-down on surfaces, speakers, magnetic phone mounts, and magnetic clasps on bags. Keep your watch away from these during extended contact.
If your automatic watch suddenly becomes dramatically inaccurate — gaining or losing several minutes per day after previously keeping good time — magnetisation is the most likely cause. A watchmaker can demagnetise the movement quickly and inexpensively. No damage is done by short-term magnetisation — it is reversible.
Avoid Extreme Temperature Changes
Rapid temperature changes stress the gaskets that seal a watch's water resistance. Moving from a hot shower directly into cold air, or from a cold environment into a hot one, causes the case materials and gaskets to expand and contract at different rates — potentially creating gaps in the seal.
This does not mean avoiding temperature variation entirely — that is impractical in daily life. It means avoiding extreme changes: do not wear the watch in a sauna or steam room, do not wear it in very hot water, and do not move from extreme cold directly into hot water with the watch on.
Store Correctly When Unworn
A watch left on a bedside table or in a drawer is exposed to dust, humidity, and occasionally the magnetic fields of nearby electronics. Correct storage means a cool, dry environment away from direct sunlight and strong magnetic sources. A basic watch box or roll provides adequate protection for most watches in daily rotation.
For automatic watches left unworn for extended periods: the lubricants in the movement can pool or dry out if the movement sits static for months. If you intend to leave an automatic watch unworn for more than a month, wind it manually every few weeks to keep the movement components lubricated through their range of motion.
Cleaning Your Watch
The Case and Bracelet
A stainless steel case and bracelet accumulates skin oils, sweat, dust, and debris in the bracelet links and around the lugs with daily wear. This accumulation is normal — but left unaddressed it causes discolouration and, over extended periods, can contribute to corrosion in the bracelet link pins.
Clean the case and bracelet every 2 to 3 months with a soft brush — a toothbrush works well — and warm soapy water. Ensure the crown is fully screwed down before any water contact. Pay particular attention to the bracelet links and the areas around the lugs where debris accumulates. Rinse with fresh water and dry completely with a soft cloth.
For the case surfaces, a microfibre cloth removes fingerprints and light debris from polished surfaces without scratching. Avoid paper towels and tissues — these can leave fine scratches on polished steel over time.
The Crystal
Sapphire crystal can be cleaned with any soft cloth — microfibre is ideal. The crystal will not scratch from the cloth material. For stubborn fingerprints or smears, a small amount of glass cleaner on the cloth works effectively. Do not spray cleaner directly onto the watch face — apply it to the cloth first.
Mineral glass crystals require gentler handling. A microfibre cloth only — no abrasive materials and no cleaners that could leave residue in surface scratches.
The Leather or Rubber Strap
Leather straps require specific care. They should not be submerged in water — remove the watch before swimming if it is on a leather strap, or swap to a rubber or NATO strap for water activities. Wipe leather straps with a slightly damp cloth after sweaty wear and allow to dry naturally. Applying a small amount of leather conditioner every few months prevents drying and cracking.
Rubber straps are more robust. Clean with soapy water, rinse, and dry. Avoid prolonged exposure to direct sunlight which degrades rubber over time.
The Crown Area
The crown and crown tube accumulate debris — particularly if you live in a dusty environment or work with your hands. A soft brush can clean around the crown stem and tube. Ensure the crown is screwed down immediately after cleaning.
Movement Care: Automatic Watches
Winding Correctly
Manual winding of an NH35 automatic: pull the crown to Position 1 — one click out from the fully screwed-in position. Turn clockwise for 20 to 30 rotations. You will feel the resistance increase as the mainspring approaches full wind. Do not force it past the point of firm resistance — modern automatic movements have a slipping clutch that prevents overwinding, but there is no benefit to forcing the mechanism.
Do not wind the movement while it is on your wrist. The angle is awkward and the sideways pressure on the crown stem during winding is not ideal for the winding mechanism. Remove the watch and hold it in your other hand while winding.
"The JB Classic was my first automatic watch. I wound it every morning for the first week — about 20 rotations — then wore it all day. By evening it was still keeping time. I had expected it to stop. Kevin explained that the rotor charges the mainspring throughout the day from wrist movement — morning winding just gives it a head start. Understanding that changed how I thought about the watch. It is a living object. That is different from every watch I owned before."
— Marcus T. · Atlanta, GA · ✓ Verified buyer · JB Classic Mod Watch
Setting the Time
Pull the crown to the time-setting position — Position 2 on an NH35. The second hand stops (hacking). Set the time. Push the crown back in firmly. Screw it down if applicable.
One important note: do not adjust the date between approximately 9pm and 3am on the watch dial. During this period, the date mechanism is engaged in its automatic date-change cycle and manually advancing the date during this window can damage the date wheel. If you need to set the date, either do it outside this window or advance the hour hand past midnight to complete the automatic date change first.
Service Intervals
An NH35 automatic movement should be serviced every 3 to 5 years. A full service involves disassembling the movement, cleaning all components ultrasonically, replacing worn parts, applying fresh lubricants throughout, reassembling, regulating for accuracy, and testing water resistance.
The cost of an NH35 service at a qualified watchmaker is typically $50 to $150. This investment extends the movement's reliable lifespan by decades. A movement that is never serviced will show progressive accuracy degradation, increased power reserve loss, and eventually component failure.
Signs the movement needs servicing: accuracy has deteriorated significantly from its normal rate, the power reserve has shortened noticeably, the watch stops more frequently than expected, or it has been more than 5 years since the last service.
Movement Care: VK Meca-Quartz Watches
Battery Replacement
The VK63 and VK64 meca-quartz movements use an SR927W silver oxide battery with an approximate lifespan of 3 years under normal use. The indicator that the battery is nearing the end of its life: the seconds sub-dial hand begins jumping in 2-second intervals rather than smooth continuous movement. This is the battery-end warning built into the movement — you typically have 2 to 4 weeks from this point before the watch stops completely.
Battery replacement costs $5 to $15 at any watch repair shop, jeweller, or watchmaker. The SR927W is a standard battery available at electronics retailers and watchmakers worldwide.
After any battery replacement — or any case opening — water resistance must be retested before water exposure. Opening the caseback disturbs the caseback gasket. A qualified watchmaker who replaces the battery will reseat the gasket and can retest water resistance at the same appointment.
Chronograph Maintenance
The mechanical chronograph mechanism in the VK meca-quartz benefits from occasional use. If you own a chronograph watch that you never use the chronograph function on, activate it occasionally — start, run for a minute, stop, reset — to keep the mechanical components moving through their range of motion. This is not critical, but it is good practice for any mechanical complication.
Never press the chronograph pushers underwater. This creates a direct pathway for water to enter around the pusher tubes — bypassing the case's water resistance entirely. Always stop the chronograph before any water exposure.
Water Resistance: Maintaining It Over Time
Water resistance is not a permanent specification. It degrades over time as gaskets compress, age, and eventually lose their sealing effectiveness. The rated water resistance of a watch at the time of manufacture will not be maintained indefinitely without maintenance.
Annual Water Resistance Testing
For any watch regularly used in or near water, annual water resistance testing is the single most important maintenance action. A watchmaker can test the watch under simulated depth pressure — typically in a matter of minutes — confirming that the rated water resistance is still being achieved.
The cost is typically $10 to $20. This small investment confirms that the watch will perform as rated in water. Without testing, you are trusting a water resistance rating that may be years old and may no longer be valid.
Gasket Replacement
The gaskets that seal the crown tube, caseback, and crystal degrade over time. Most watchmakers recommend replacing gaskets every 2 to 3 years on watches used regularly in water. This is typically done as part of a service or battery replacement. The cost is minimal and the benefit to long-term water resistance is significant.
After Any Case Opening
Any time the caseback is opened — for a battery replacement, for a service, for any reason — water resistance must be retested before water exposure. Do not assume the factory water resistance rating is restored by simply closing the caseback. The gasket must be correctly reseated and the water resistance verified.
Common Mistakes That Damage Watches
In 12 years of handling warranty claims and support queries, these are the mistakes that damage watches most frequently.
Pressing chronograph pushers underwater. This is the most common cause of water damage to chronograph watches. The pushers create a direct pathway for water entry when pressed. Never press them while submerged.
Wearing into a sauna or steam room. The extreme heat and steam degrade gaskets rapidly and can cause the crystal adhesive to loosen. Saunas and steam rooms are the environment most damaging to watch water resistance.
Setting the date between 9pm and 3am on the dial. On date watches with automatic date-change mechanisms, manually advancing the date during the date-change cycle can strip the date wheel. Set the date outside this window.
Not rinsing after saltwater exposure. Salt left to dry on a watch accelerates corrosion and degrades gaskets. Rinse immediately after any sea use.
Leaving the crown unscrewed. A screw-down crown provides no water resistance benefit unless it is actually screwed in. This is the most common cause of water damage to watches with rated water resistance — the crown was not screwed down before water exposure.
Dropping onto hard surfaces. Sapphire crystal, while extremely scratch-resistant, is more brittle than mineral glass. A direct sharp impact — face-down onto tile or concrete — can crack sapphire. The movement can also be damaged by impact. Treat the watch with reasonable care.
Never servicing an automatic movement. An automatic movement run for years without servicing will show progressive degradation. The lubricants dry out, accuracy suffers, and eventually components wear. A $50 to $150 service every 3 to 5 years is the correct long-term ownership cost of an automatic watch.
"I pressed the chronograph pusher on the Blue Speed while the watch was wet — not underwater, just wet from washing my hands. Water got in through the pusher tube. Kevin responded to my email the same day. He walked me through the warranty process and the watch was replaced within two weeks. The replacement arrived with a note reminding me about the pushers and water. I have not made that mistake again. The support was as good as the watch."
— Andrew S. · Chicago, IL · ✓ Verified buyer · Blue Speed Mod Watch
Frequently Asked Questions
How often should I service my automatic watch?
Every 3 to 5 years for a full service on an NH35 automatic. Signs it needs service sooner: significant accuracy degradation, shortened power reserve, or stops more frequently than expected. A service costs $50 to $150 at a qualified watchmaker and extends the movement's reliable lifespan significantly.
How do I clean my watch at home?
Soft brush and warm soapy water for the case and bracelet — with the crown fully screwed down. Microfibre cloth for the crystal. Slightly damp cloth for leather straps — do not submerge leather. Rinse with fresh water and dry thoroughly after cleaning.
My automatic watch is suddenly very inaccurate — what is wrong?
Sudden dramatic inaccuracy in an automatic watch is most commonly caused by magnetisation of the hairspring. Keep the watch away from magnetic sources — laptops, speakers, magnetic phone mounts — and take it to a watchmaker for demagnetisation. This is quick, inexpensive, and causes no permanent damage.
Can I wear my watch in the shower?
Yes — with the crown fully screwed down and the watch rated to 50 metres or above. Avoid very hot showers as heat degrades gaskets over time. Rinse and dry the crown area after showering. The Green Milsub at 200 metres handles all water activities comfortably.
How do I know if my watch needs a new battery?
On a VK63 or VK64 meca-quartz, the seconds hand begins jumping in 2-second intervals — rather than smooth motion — when the battery is nearing the end. This gives you 2 to 4 weeks to replace the battery before the watch stops. Replace with an SR927W battery at any watch repair shop.
Does sapphire crystal need any special care?
No — sapphire crystal is highly resistant to scratching and requires only a soft cloth to clean. Unlike mineral glass, which scratches from everyday contact, sapphire resists virtually all everyday materials. Clean with a microfibre cloth. Avoid dropping the watch face-down on hard surfaces as sapphire, while extremely hard, is more brittle than mineral glass under sharp impact.
Kevin's note: In 12 years of warranty claims, the three most common causes of damage are: pusher pressed while wet, crown not screwed down before water exposure, and sauna or steam room wear. All three are preventable with a two-second check before water contact. Every watch I build has a 2-year warranty — but the watches that generate the best long-term ownership stories are the ones whose owners understand these three things before the watch goes on their wrist for the first time.
The Bottom Line
A quality watch — sapphire crystal, named movement, real water resistance — rewards a small amount of informed daily care with decades of reliable service. The habits that matter most are simple: screw the crown down before water exposure, rinse after saltwater use, service the movement every 3 to 5 years, and never press chronograph pushers underwater.
Every watch we build at ZJani Watches is covered by a 2-year warranty against manufacturing defects and a 30-day return policy. But the watches that generate the best long-term ownership experiences are the ones whose owners understand how to care for them.
Also worth reading: How to Choose Your First Automatic Watch: A Complete Guide
Also Worth Reading
Kevin has been building ZJani Watches for 12 years. The full collection is available at zjaniwatches.com. Every piece ships with a 2-year warranty, 30-day returns, and free worldwide shipping.
