Watch Maintenance

MILITARY WATCHES GENERAL INFORMATION AND DETECTING THE FAKES

If you want to contact me with comments email: ian.crowley@military-watches.net

Military Watch Maintenance

Military Watch Maintenance and care

To ensure many years of trouble free operation from your military watch we strongly recommend the following watch care tips be observed:

Do not operate or push-buttons under water or while the watch is wet.
Tighten any screw lock crown completely.
If the watch comes in contact with salt water be sure to rinse it off with warm fresh water to remove any trace of salt otherwise salt water corrosion can occur.
If the watch comes in contact with chemicals or corrosive materials (mechanics and aircraft engineers please note) the watch should be thoroughly cleaned to remove all traces otherwise chemical corrosion can occur.
Do not wear your watch in the shower, spa, bath or hot pools. No matter what the water resistance rating. Hot water will damage the water tight seals.
Do not place a watch in a bathroom while showering as the temperature difference can cause steam to be drawn into the case of the watch. Corrosion will occur.
If the watch does get wet inside do not store it in a closed container. Take the watch immediately to a jeweller or watchmaker for drying out otherwise the watch will corrode.
Replace batteries as soon as possible as they can leak causing corrosive internal damage to the watch. A sign of imminent battery failure on analogue watches (if they don’t have an end of life indicator) is that they will stop if not worn on a cold night.
On battery change a watch with a rating greater than 30 metres will need a pressure test to validate the water resistance rating.
The push-buttons and crown of a watch are precision parts that require regular maintenance. These parts also have rubber seals that need regular lubricating and cleaning. The push-buttons and crown of a watch should be cleaned and lubricated every two years to reduce wear on these parts and to assist water security. Ask for these to be cleaned when you get the battery changed.
Watches used for scuba diving should be tested every six months for water security
Watches should be cleaned and lubricated every 5 years. The oils used in watches gel with age which will eventually cause the watch to stop. The oils also accumulate dirt which will accelerate the wear of the moving parts.
Regular cleaning of metal watch bands is important, not only for your own personal hygiene but for the person that eventually will change the battery on the watch. This can be done with a mild detergent, warm water and an old toothbrush. Ensure the watch is 50 metres water resistant or greater.
NATO Straps can be removed and washed in a washing machine. Stains can be removed by soaking in Napisan.

Battery Change: It is always best to have the battery in your watch replaced at regular intervals to reduce the risk of damage to the movement from leaking fluids from an expired battery. A flat battery has a greater chance of leaking fluids that can result in expensive repairs. Usually the acid fluid from the battery will track up the contacts into the movement making it necessary for the movement to be replaced. As soon as the battery is flat have it replaced by your jeweller. If your watch is water resistant be sure to have the gaskets replaced and the watch water tested at the same time.

Rust on Metal Bands: The metals used for military watch bands vary from stainless steel to titanium. All of these metals have a high resistance to rust. Among these metals, stainless steel is used more in quantity than other metals due to its high workability and durability as well as its pleasing appearance. However these fine properties of stainless steel are not effective unless used correctly.

The "stainless" property of stainless steel is due to an oxide layer, chromium oxide or the like covering the surface of the metal. This oxide layer is liable to cause rust if the amount of oxygen becomes short. Dust or dirt will affect good exposure between the oxide layer and oxygen. At the same time, salt or fatty acids contained in perspiration will cause rust on a stainless steel strap. Accordingly, please remember to keep your watchband clean at all times and in the fresh air whenever possible.

Proper Care of the Band: As the watchband touches the skin directly on your watch, it becomes easily soiled with perspiration and dust. Many watch owners are not aware of the necessity of keeping the watch case and band clean. Perspiration or dust absorbed by a leather band, in particular, can cause a breakdown of the leather reducing the life of the strap. In the case of metal bands, perspiration and dust sticks more easily due to its structure. The use of a contaminated watch band will not only reduce the life of your bracelet and connecting pins, but may also soil clothing that it may come in contact with.

Care of Metal Watch Bands: After moving the metal bracelet from the watch, use a soft brush and warm soapy water to clean the bracelet. Be sure to rinse thoroughly in clear water and completely dry it before reinstalling it on your watch. If you have a large amount of perspiration on your wrist while wearing the watch, the band must be completely dried out with a soft cloth as soon as possible. Allowing perspiration to accumulate will cause the finish to dull and may even cause damage to vital components of the bracelet. Do not use chemicals such as paint thinner when cleaning your watch. This may damage the finish and cause irritation to the skin.

Care of Leather Straps: A leather strap is more susceptible to damage and premature wear from moisture than a metal band. A leather band may be damaged if moisture or perspiration is allowed to remain on or saturate the band. You should wipe both the inside and outside of your strap daily with a soft dry cloth to remove collected contaminants. If your watch becomes saturated with moisture be sure to allow the strap to become completely dry before wearing the watch again.

Care of the Rubber Strap: As the watchstrap touches the skin directly it can become soiled easily with perspiration or excess oils. Periodic cleaning of the rubber strap is recommenced. Using an old tooth brush and a mild detergent thoroughly cleanse the inside and outside of the strap. Completely rinse off any soap residue and then thoroughly dry the strap. After exposure to salt water rinse the strap in clean water as soon as possible. Some people even use a rubber protectant to keep the strap soft. The softer and dryer the strap the longer it will last.

WATER RESISTANCE

If a watch is simply described as "Water Resistant" or "WR", then it is splash proof. There is no absolute guarantee, but this means that it should be fine in normal wear, including going out in the rain and hand washing, but not where any immersion in water takes place such as washing dishes, showering, bathing, etc.

Water Resistant to 30m/3ATM/98ft
Suitable for everyday use and will withstand accidental splashing, but NOT suitable for swimming.

Water Resistant to 50m/5ATM/164ft
Suitable for everyday use and swimming, but NOT suitable for poolside diving, snorkelling or water sports.

Water Resistant to 100m/10ATM/328ft
Suitable for everyday swimming and snorkelling, but NOT suitable for high board diving or sub aqua diving.

Water Resistant to 200m/20ATM/662ft
Suitable for all high impact water sports and scuba diving at depths NOT requiring helium gas (at these depths it is recommended that a professional diver's watch be purchased).

	Water Resistant	50m 5 bar	100m 10 bar	150m 15 bar	200m 20 bar	1000m 100 bar
Accidental Splashes	Yes	Yes	Yes	Yes	Yes	Yes
Swimming	No	Yes	Yes	Yes	Yes	Yes
Swimming, Snorkelling, Water Sports	No	No	Yes	Yes	Yes	Yes
Scuba Diving	No	No	No	No	Yes*	Yes*
Professional Deep Sea Diving	No	No	No	No	Yes*	Yes*

*Only watches designed specifically for the purpose should be used for diving, as they fully comply with the international standards for divers watches.

Watch manufacturers use other terms to measure water resistance:
• A.T.M. (atmosphere), where 1 A.T.M. equals 10 metres.
• Bar, where 1 bar equals 10 metres

ACCURACY

When it comes to accuracy there is one very important fact you need to know in advance. A $42 MWC Vietnam watch will keep time just as well as, and possibly better than, a top of the range MWC, CWC or Marathon mechanical or possibly even a $20,000 solid gold mechanical Omega, Rolex, or other high end watch.

If that last statement surprised you, read the rest of this section carefully.

All watches tend to gain or lose a few seconds over a period of time. These are small mechanical or electro-mechanical devices that are counting out 86,400 seconds per day. Even if a watch is 99.9% accurate, it will still be off by a minute and a half in only 24 hours! So even a mediocre wristwatch has to be well over 99.9% accurate to even begin to be useful on an ongoing basis.

So, what is a reasonable expectation of accuracy from a wristwatch? The table below is a pretty accurate guide as to what can be expected.

	Seconds gain/loss per day
	Worst	Typical	Best
Vintage mechanical watch in good repair	+/-60	+/-15	+/-5	99.9826%
Modern mechanical watch non-certified	+/-10	+/-5	+/-2	99.9942%
Modern mechanical watch chronometer certified	+6/-4	+/-3	+/-1	99.9977%
Modern quartz watch non-certified (normal)	+/-2	+/-1	+/-0.1	99.9998%
Modern quartz watch chronometer certified (rare)	+/-0.02	+/-0.02	+/-0.0	99.9999%

While some people desire wristwatches with extremely high accuracy over long periods of time, it is seldom for any reason besides personal satisfaction. The few professions that depend on precision time synchronization (such as astronomy, global navigation, train scheduling, and broadcasting) base their operations on high precision time sources, not consumer wristwatches.

So why would anyone want a less accurate watch?

The short answer is that pretty much any modern wristwatch from a reputable brand is more than accurate enough for normal use. So some people (myself included) prefer older mechanical watch technologies over the small accuracy advantages of quartz watches. In the 1970s everything was heading towards quartz watches but by the 1990s handwound and automatic mechanicals were once again firmly establishing themselves in the mid ranges and high end market.

Are quartz watches always more accurate than mechanical ones?

Typically they are, but not always. Accuracy and precision are not exactly the same thing.

It is important to remember that even when a mechanical watch is allowed to vary +6/-4 seconds per day, that does not mean it will consistently vary by that high an amount each day. Mechanical movements--except the very rare 'turbillon' movements that correct for it--are noticably affected by the gravitational pull of the Earth. It only takes a performance distortion of 1/1000th of a percent for a watch movement to be one second less accurate in a day. This causes the performance of mechanical movements to be somewhat different from day to day when not stored in a fixed position. The good news is that the actual variations of a mechanical watch will often cancel each other out. This means a mechanical watch will tend to be more accurate over a longer period than the single-day COSC measurement may imply.

The day-to-day performance of quartz is much more consistent than mechanical under identical conditions. Quartz performance is affected mainly by temperature changes and weakened batteries. So a quartz watch that you measured to gains 0.5 second yesterday will be consistently increasingly off correct time by about that amount. You can be pretty certain that in 60 days, it will be about 30 seconds off. At the end of a year, it would be likely be over 180 seconds off.

Compare that to a mechanical watch that you measured to gain 2 seconds yesterday. It would seem that our example quartz watch is 4 times more accurate than this. But while the daily measured daily variations seem much higher, they are not likely to be as consistent, so will have a dampening effect. You cannot accurately predict that this mechanical would therefore be off by 120 seconds at the end of the same 60 days. It might be right on time, or it may be 200 seconds off. That broader range of variations allows most mechanical watches to stay closer to correct time than the daily variation rate implies. Over a year, some mechanicals can on average stay closer to correct time without having to be reset than a quartz watch might where others always tend to gain roughly the same amount each day.