Conservation and restoration of clocks
The conservation and restoration of clocks refers to the care given to a clock to either prevent or resolve issues faced during its life cycle. The variety of materials from which a clock may be constructed and the complexity of clockwork warrant such care to be taken by a clock owner so that a clock can continue to function.
- 1 Preventive conservation
- 2 Typical types of damage
- 3 Conservation and restoration
- 4 References
Proper handling, suitable storage and display environments, and regular maintenance can together prevent issues from arising and impacting a clock’s sustainability. Such controls can extend the life of a clock.
Certain precautionary measures taken by a clock handler can deny opportunities for damage to occur:
- Loose items worn by a handler have the potential to come into contact with and cause damage to a clock. Removal of these items prior to clock handling can lower the risk of damage.
- Wearing “[...] cotton or rubber gloves when handling the metal portions of the clock”  can limit opportunities for transfer of contaminants from hands to clock surfaces.
- Pendulum damage during clock movement can be prevented by either removing the pendulum or fixing it within the interior of the clock via a latch or padding prior to clock movement. This can also prevent damage to other interior components.
- A clock "[...] should always be grasped at its most sturdy area"  and moved from one location to the next on its back.
- The correlation of the size of a clock with the number of people moving it can ensure the safety of the clock. A small, mantle clock for example may only require one mover, while a tall clock can necessitate a number of movers to safely carry it to another location.
Storage and display
Proper storage and display mechanisms can work to ensure a clock’s safety. The use of a solid, sturdy surface when storing or displaying a clock can prevent it from falling on a hard surface. A wall clock for example requires a secure attachment "[...] to a wall if accidents are to be avoided and clocks are to run properly.”  Motion sensitive lighting and use of non-direct light sources can limit the amount of light and heat withstood by a clock, both of which are sources of clock damage. A clean clock environment can eliminate opportunities for dangerous contaminants to come into contact with a clock. An HVAC system can add an extra level of security by removing such contaminants from the air.
Humidity and temperature levels
The humidity and temperature of the environment in which a clock is being displayed or stored can adversely affect the clock’s condition. Damage may be avoided by maintaining certain levels of humidity and temperature within the clock environment, dependent on the materials from which the clock is constructed.
- a. Wood clocks
- The ideal humidity and temperature ranges for clocks whose cases are made from wood vary depending on the season. In the summer, an environment with a temperature of 70 to 75 degrees Fahrenheit and 40% to 60% relative humidity is suitable. During the winter, an environment with a temperature of 70 degrees Fahrenheit and 35% to 50% relative humidity is prime.
- b. Metal clocks
- Clocks whose cases are made from metal function well in an environment with a temperature of 68 degrees Fahrenheit and a relative humidity of 30%.
Regular maintenance of a clock can ensure its long-term preservation.
Visual inspection can determine whether a clock should be cleaned and/or lubricated, whether any signs of infestation and/or damage exist, and whether a clock should be wound and/or set to the correct time.
- a. Cleaning, polishing, and lubrication
- Regular clock surface dusting can negate opportunities for corrosion or abrasion as a result of dust buildup. It should be stated that such surface cleaning can also result in a loss of information about a clock’s history, as “[...] various “dirt” or “salt” deposits can provide precious clues to an objects past [...].”  Dust and other contaminants can also cause clockwork wear, as “the abrasive particle will become imbedded into the bearing wall and act as a piece of “sandpaper [...].”  Regular clockwork activities can also lead to wear, as lubricants are known to degrade over time. Loss of clock function due to clockwork wear can be avoided through regular clockwork cleaning, polishing, and lubrication performed by a trained professional. In performing such maintenance, a professional will disassemble clockwork so that it can be thoroughly examined “[...] for worn or broken parts, fatigued springs and accumulations of dirt or oil.” 
- b. Winding and setting
- In order to function as time keepers, and to prevent damage to clockwork, clocks must be regularly wound. An established winding schedule eliminates the threat of over-winding. Regular winding can also ensure that clockwork is still functioning. In setting the correct time, the minute hand is turned clockwise to the desired time.
Typical types of damage
Damage can occur via a variety of mechanisms, either rooted in human error or naturally caused.
- a. Mishandling
- The failure of a handler to remove loose items from their person can result in these items striking a clock’s surface. A handler who uses his or her bare hands to touch or transport a clock exposes the clock to contaminants, leaving “unsightly and potentially damaging marks.”  A handler who chooses to drag rather than lift a clock “[...] can place stress on the legs and feet of the clock.”  Lifting a clock via false handles or non-sturdy components may cause these parts to snap off of the clock, potentially leading to the clock falling and smashing on a surface.
- b. Over-winding or improper hand setting
- Improper clock winding and hand setting procedures can cause serious damage to clockwork components. The use of an inappropriate key to wind a clock is one such improper procedure. The manner in which a clock is wound is also important, as “[...] considerable and potentially expensive damage can be caused by not winding gently and steadily”, as well as by turning the key one too many times.
- In terms of improper hand setting, manually moving the hour or seconds hand rather than the minute hand in an attempt to set the time can be damaging, as can be counterclockwise hand turning. Moving the minute hand ahead on a clock by several hours when setting the time can also lead to clockwork damage. For this reason, “Rather than turning the hands forward through several hours it is better to stop the clock and re-start it when the time matches that on the dial.” 
- c. Unsuitable storage or display
- Unsuitable storage and display environments pose great risks to a clock’s condition. Placement of a clock on an unstable surface or non secure mounting on a wall can cause a clock to fall when external vibrations or human caused accidents occur.
- d. Improper cleaning and polishing
- Many cleaners and polishers contain properties that “[...] have been proven to age poorly.”  Resultantly, the use of such cleaners and polishers can prove detrimental. The use of ammonia based cleaning products for example on brass clock components can lead to an irreversible form of damage called Stress Corrosion Cracking. Depending on the type of metal on which it is used, a metallic brush employed to apply cleaning products not only can create the proper conditions for corrosion, but can “[...] remove any protective oxide layers even with careful use.” 
- e. Improper lubrication
- Attempts by non-professionals to lubricate or repair clockwork can lead to serious damage and loss of clock functionality. A lubricant applied without first cleaning and polishing clockwork to remove the previous lubricant and contaminants can result in wear rather than prevent it. The combination of the newly applied lubricant with the previous lubricant often results in “[...] an unwanted chemical reaction between the two lubricants [...].”  A careless lubricant choice can result in the use of inappropriate or "Poor-quality oil" on clockwork, which "can become sticky leading to mechanical problems."  The inexperience of a non-professional can also lead to “the use of too much oil, or oil in the wrong place”  during attempts to lubricate clockwork. The application of too much of a lubricant can be damaging because it “[...] usually causes the lubrication to run out of the bearing and by capillary action will cause the bearing to go dry.”  Totally ignoring the lubrication needs of clockwork can be jeopardizing not only because of lubricant degradation, but because of the acidic nature of the organic lubricants often used in antique clocks.
- a. Humidity and temperature
- The amount of water in the air and temperature of a given environment can play a direct role in clock deterioration. “[...] extremes in temperature and humidity”  can cause drastic changes in the materials from which a clock is made, inevitably leading to damage. Placement of a clock for example near "a heat source of any kind, including strong sunlight or a mantel over a working fire [...] can cause damage to cases and movements." 
- b. Pests
- Clocks are as susceptible to pest damage as any other object constructed from organic materials. Pests that are known to infest clocks are attracted to the organic materials from which a clock may be constructed:
- c. Light
- Over-exposure to light can impact clock materials in a number of ways. Heat from a light source can cause the varnish or finish on a clock surface to melt, resulting in a sticky surface to which harmful contaminants can become attached. Too much light exposure can also result in changes to finish color, as well as cause finish deterioration “[...] resulting in a cracked, brittle and/or “alligatored” appearance.” 
- d. Contaminants
- Contaminants themselves vary and come into contact with a clock by way of various means. The following are two such examples:
- Dust is one such contaminant which settles on a clock’s surface. If not addressed, dust buildup can lead to abrasion and corrosion.
- Oil is transferred to a clock surface when a clock is handled with bare hands. The presence of oil on a clock can cause damage, particularly corrosion when metal clock components are touched.
Types of clock damage
Damage can impact all components and materials from which a clock may be constructed.
Due to its porous nature, wood is significantly impacted through contact with water. When humidity is high, the excess water in the air is absorbed, resulting in wood expansion, while little to no water in the air when humidity is low can cause wood shrinkage. Such changes in character from the wood’s original state can lead to damage. Types of low humidity-related wood damage include “[...] structural cracks, lifting veneer and inlays, gaps in joints and the embrittlement of adhesives." 
Similar to wood, interaction with water can also prove detrimental to metal. When contaminants come into contact with metal, they either combine with any present moisture or attract moisture to the metal. This “[...] combination with moisture can produce corrosion.” 
Finish or paint damage
Finish damage can occur as a result of the use of cleaning products and/or polishes on a clock’s surface. Rather than perform their intended duty to assist in the preservation of a clock, some products “can actually darken or become opaque with age, resulting in a dark, dull and often irreparable finish.”  Any words or images painted on a clock surface can become faded or even removed when these delicate pieces are touched and exposed to moisture from hands.
Interior or clockwork damage
Clockwork damage can be inflicted via over-winding, interaction with contaminants, ill-advised lubrication, and clock movement when a pendulum is not secured prior to the clock being moved. A free swinging pendulum can itself be damaged and can inflict damage onto other interior components during such clock movement.
Conservation and restoration
Interventive actions can be taken by trained conservators when clock issues arise, with treatment varying depending on the type of clock and situation.
A conservator who specializes in clock care will have the qualifications and training to properly treat a clock with the wherewithal to “[...] not totally compromise the historical worth of the object [...].”  Conservators rely on a system of examination, documentation, and research prior to treatment so that proper treatment is received, as “Sometimes the only way one can understand the detailed history, quirks, and specific eccentricities common to a particular timepiece is by studying it to glean as much information from it as possible [...].”  Aside from pinpointing clock issues and providing care to a clock in need, conservators are also able to impart knowledge about procedures like clock winding to ill-informed clock owners so that future clock damage due to human error may be avoided.
Example: Anglesey Abbey Pagoda Clock
Horological conservators at West Dean College were responsible for the treatment of an 18th-century pagoda clock sent from the historic house Anglesey Abbey by the National Trust. In starting the project, examination of the clock revealed that "The automata and clock elements seem to be running, but struggling, and the music sounds as though it needs a few extra hands to help play its tune."  The clock was then disassembled, and care was taken to document information about each of the over 600 components both textually and photographically, including measurements and where each component fits within the clock. "After examination, each component was cleaned and dried, wrapped in acid-free tissue, and stored with the catalogue number." 
- Fahey, Mary M. "The Care and Preservation of Clocks". Benson Ford Research Center. The Henry Ford. Retrieved 19 November 2015.
- "Care and Conservation of Clocks". Conservation Register. The Institute of Conservation. Retrieved 20 November 2015.
- Moss, James. "Concerns regarding the Conservation of Functional Horological Objects". Conservation OnLine. Foundation of the American Institute for Conservation. Retrieved 2 December 2015.
- "Horological Conservation". NAWCC. National Association of Watch and Clock Collectors. Retrieved 2 December 2015.
- Cox, Brittany N. (5 June 2012). "Anglesey Abbey's Pagoda Clock". Current Projects. West Dean Conservation. Retrieved 20 November 2015.
- Cox, Brittany N. (28 June 2012). "The Pagoda Part 2". Current Projects. West Dean Conservation. Retrieved 20 November 2015.