The St.Petersburg Centre of Watch & Clock Restoration

Frost and sun

Why is it not recommended to expose watches to an abrupt temperature drop? Is there any exclusion from this rule? What does ‘temperature compensation’ mean? A famous St.-Petersburg watchmaker Konstantin Chaykin gives us a good piece of advice.

To keep watches for a long time in ideal state you should protect a fragile mechanism from negative influence of environmental factors – this is one of the main rules. Abrupt temperature drops and long exposure to direct sun rays refer to such negative environmental factors. Maximum temperature range allowable for the specific watch model exploitation is usually indicated in manufacturer manual. Specially for those who likes hyperactive style of life, who takes part in expeditions to the North Pole, regularly visits resorts in hot countries or is keen on diving in icy water I should note that the modern sports watches are the most heat-resistant. However, there are some restrictions even for this kind of watches.

Attention: temperature!

So it should be remembered that not only systematic but even single violation of standards established by a manufacturer can break the regular work of watches and as a result lead to an expensive repair.

In winter extremely unfavorable conditions for your watch can arise if you carry it for a long time in pocket of your overcoat or if you accidentally on a frosty evening forget your watch in the car for a night.

Severe frost is a reason for solidification of lubrication in clockwork that can result in deterioration of observation accuracy. At low temperatures some condensate is generated and some liquid penetrates inside clockwork. Later on this can put clockwork out of action. Additionally, in cold weather the geometrical sizes of various clockwork components can change. Moreover these changes occur non-uniformly because the components are made of different materials. Apart from the deterioration of observation accuracy irreversible deformations or breakage of some components can take place. If a watch crystal is adjusted hermetically it can easily break. Cold air promotes quick discharging of storage battery in quartz clock and deteriorates digital indication in the watches with liquid-crystalline display.

Provided using watches at too high temperatures the lubrication of clockwork dries up, therefore its components get worn out rapidly in hot climate. Special linings of watertight and waterproof watches also dry up and outwear leading to seal failure of watch case. The dye of clock-dial left under direct sun rays or near a source of heat can change its color or curl. If there are plastic components in clockwork they become deformed.

Useful degrees

It is mainly a balance-wheel and balance springs (hairsprings) which are responsible for the accuracy movement of mechanic clock. As the other metal components they are characterized by shrinking or expanding at any slight decrease or increase of temperature. Accordingly elasticity of a hairspring is changed: it becomes either more rigid inducing the clock to be fast or looser making the clock to be slow. It is worth noting that changes of material elasticity modulus affect 24 hours’ clock operation stronger than changes of linear expansion. It has been proved that if a balance-wheel has no temperature compensation and a hairspring is made of high-carbon steel so even 1o C temperature change results in 10-12 s change of 24 hours’ clock operation.

To compensate such strong dependence on temperature and to improve clockwork watch-makers have applied different approaches. For example, they used so-called compensation balance-wheel (split bimetallic balance-wheel made from steel and brass). It attenuated the influence of temperature on 24 hours’ clock operation up to hundredth of second. The main principal of its compensation consists of interaction of two phenomena which eliminate each other.

Compensation balance-wheel

Steel and brass have different linear expansion coefficients*. When temperature decreases split parts of balance-wheel rim turn up from balance-wheel axle, as a result its moment of inertia increases. When temperature increases the opposite phenomenon occurs. Thus change of hairspring elasticity is equilibrated by automatic change of balance-wheel moment of inertia.
* Linear coefficient of linear expansion is equal to increase in the length (mm) of a 1 meter rod being heated up to 1o C.

Technology and adjustment of clocks with such kind of balance was very laborious and expensive. Therefore while horology and metallurgy have been developing watchmakers began to apply special alloys for balance-wheel rims that had low sensitivity to temperature changes: Glucidur and Nivarox. It has been proved that these alloys are so good that at present a glucidur balance-wheel and a nivarox hairspring are applied practically in all high-quality watches.

Surprisingly, but not all clock manufacturers started struggling with environmental temperature. Some of them, on the contrary, converted it to their ally. One of such brave engineering solution was applied in an interior clock “Atmos”. This clock is the pride of Jaeger-LeCoultre Company. Under some negligibly small fluctuation of air temperature self winding of watch occurs. For example, 1oC temperature change gives an operation reserve up to 43 hours.

 

Clock model “Atmos” was invented in 1928 by an engineer Jan-Leon Revtter. In 1935 a patent for production of this clock was acquired by Jaeger-LeCoultre Company. In spite of the fact that the first specimens of this clock produced by the company were not much in demand, by 1979 Jaeger-LeCoultre Company had already produced about half a million items of this clock because in the course of time “Atmos” has gained popularity and become one of the most prestigious gifts for very important visitors in Switzerland. The clock operation principal is based on a special device used for the automatic winding up of a clock spring. This special device consists of a chamber filled with some ether (it has a very high linear expansion coefficient). The hairspring set up in a gas chamber shrinks and expands under the fluctuation of atmosphere pressure and the environmental temperature. Taking into account the peculiarities of “Atmos” clockwork, its exploitation is possible only in a stable position providing that the clock is established with the help of a special level built into the clock. The clock is constructed in such a way that small amounts of energy they get do not meet any excess resistance. So we can call “Atmos” an eternal model: speaking of the clock components, 1 year of exploitation of an ordinary clock is equal to 300 (!) years of “Atmos” exploitation.

Citizen Company has used the difference between the environmental and human body temperature in construction of one of its models. Due to this improvement the model “Tempo” does not need neither a quartz battery, nor an automatic self winding system. Sports watch. The storage battery of this watch is charged by hand's heat (automating generating system) which is an alternative source of power supply.

To sum up all mentioned above I should highlight that you cannot neglect requirements of manufacturers no matter how perfectly your watch is protected. Be attentive and punctual. Try not to expose your watch to abrupt temperature drops, keep it far from powerful heating and cooling. Only in that case your watch will serve you and keep accuracy movement for a long time.
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Kseniya Beketova
«Kotoruy Chas?», No 2/2005

 

The St.Petersburg Watch&Clock Atelier
The Centre of Watch&Clock Restoration
off. 36, Malodetskoselskiy pr.
St.Petersburg, 190013, Russia
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