The language of the clock world amazes me

I am always intrigued by the language of the clock world. Here are some terms that I have learned in the past year.


clock face showing rust staining
Clock face showing brown staining

This is a more common problem than I thought. It is unsightly feature of clock dial faces and might be a cause for concern to some collectors. This phenomenon is caused by mold growth on paper in high (over 50%) humidity. Over time the brown spots coalesce to form large areas of brown. Treatment with chlorine bleach is probably ill-advised, because it will cause metal corrosion. CLR is also not recommended because CLR is an acid. Paper conservators treat this with sodium boro-hydride, or with borax (which needs to be washed out).


bright bluish-green encrustation
Bright bluish-green encrustation

Verdigris is a bright bluish-green encrustation or patina formed on copper or brass by atmospheric oxidation, consisting of basic copper carbonate. You can see the greenish hue on the back of this century old antique carriage clock. Immersing the movement pieces in diluted Horolene is said to be one effective solution.

End Shake

End Shake is a term used to describe the movement of the pivot within a pivot hole. If the pivot is too tight there will excessive friction and the clock will not run. There must be  some perceptible end-play (end shake) and when released the arbor should drop back down to rest against the bottom plate. A too tight pivot hole can be remedied with a smoothing broach available at any clock supplier.

“Normandy Chimes” are reminiscent of the old bells of Normandy, France

Normandy strike

A clock, made by Gilbert, that strikes the hours and halves on two chime rods. Gilbert called this the “Normandy Chime” as it was reminiscent of the old bells of Normandy (Corneville) in France and it was the precursor to the Bim-Bam clock.

Harfen gong

A patented 4-hammer gong by Gustav Becker that has four rods tuned to give a medium-deep “harp” sound when struck, the origin of the gong name “Harfen (Harp) Gong”. The Gong Base has “Oest. Pat” cast into the metal showing the specific patent for this design was Austrian.


Columns or posts that are found on the sides of a tall shelf clock or tall clock running vertically. These are decorative, but also add strength to the cabinet.


The study of friction, wear, lubrication, and the design of bearings; the science of interacting surfaces in relative motion. This is the reason why engine oil and many other kinds of oil should not be used on a clcok. Engine oil is designed to be hydrophilic (absorb or dissolve in water) and coat internal parts which is the opposite of what clock oil is designed to do.


The almost triangular space between one side of the outer curve of an arch found on clock faces.

Four spandrels surrounding the chapter ring
Four spandrels surrounding the chapter ring on this Hermle bracket clock

Rathburn Bushings

Bushing a clock without disassembling is never a good thing. For most purposes Rathburn Bushings are no-no and for those who are really desperate they are at best, a band-aid treatment. I have read about them and seen photos but have never actually seen one in a clock but for about $8 on that old familiar auction site you can buy a package of 10.  To install, one places a Rathburn bushing over a worn pivot hole and screw or solder onto the plate. Not my preferred choice for clock repair.

Helper springs

I am clear on the function of helper springs/wires but what I have learned is that the gauge of wire is a function of where the spring is located on the movement. Let’s begin by describing the purpose of helper springs. They might look like they have been added later but they are actually part of the original manufacture and their purpose is to maintain tension on lifting levers, locking levers and hammers. What I did not realize until recently is that the gauge of wire is important for the amount of strength required for a particular lever. Lower gauge (thicker) wire is used for hammer levers because it is stronger and more tension is required to strike the gong/rod and higher (thinner) gauge wire is used for maintenance levers which require less tension. In the photo below you can see a thin helper wire that looks like it was wound by hand (not by me) on the lever arbor.

Helper wire for Sessions movement
Helper wire (indicated by arrow) for Sessions movement

Chinoserie: is the European interpretation and imitation of Chinese and East Asian artistic traditions, especially in the decorative arts, garden design, architecture, literature, theater,  musical performances and clocks. The pagoda style bonnet in this Scottish made Hugh Gordon long-case clock is a good example of a chinoserie influence.

Hugh Gordon throat
Hugh Gordon long-case clock in the Chinoserie style

There you have it. These are just a few of the terms I learned in the past year. Clock collecting and repair is such a fascinating hobby; it expands ones vocabulary and is a source of new and interesting words every day.


4 thoughts on “The language of the clock world amazes me

  1. Hey Ron, I would like to point out just one or two small corrections or additions to some of the definitions. While a bunch of these are not necessarily clock-specific terms (like foxing and verdigris) I can agree that they still all apply to clocks.

    One term that is not entirely correct is “pilasters”. Pilasters are specifically flat rectangular columns. They are used extensively in architecture and furniture, especially along flat walls. They can be used on clock doors (usually in earlier architectural style cases) or more often they are seen on American Black Mantle (temple style) clock cases along the fronts. 1/4 round columns or rounded columns in general don’t count as pilasters. Pilasters are very often reeded or fluted along their length.

    Spandrels are normally corners around a square dial (as you point out), but they can also be the curved/triangular kind found in an arch above the dial. These often feature stylized dolphins. They are not always necessarily triangular, as there are many oddly shaped dials (picture Harrison’s H1 for example).

    I hope you will continue to add to the list of horological terms (in more posts) from time to time. As I’m sure you know, there are hundreds more terms. A few that come to mind: Gridiron, Huygens Endless Rope Drive, Ratchet/Pall, Maintaining Power, Broaches, Flirt, Cock, Cam, Locking Wheel (or Count Wheel), Motion Works, etc.


  2. I always said that knowing the hobby’s specific terms is a must for every collector. I think it’ll be interesting to find the similar terms in foreign languages, other than English. 😉 Have a great time!

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