How to Inspect Clock Pivots and Determine When Bushings Must Be Replaced

December 16, 2025

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Why Proper Mainspring Cleaning Matters

The mainspring is the primary power source of a mechanical clock. If it is dirty, dry, or coated in hardened oil, the movement will never perform properly. A contaminated mainspring cannot unwind smoothly, which causes weak power delivery, erratic timekeeping, sluggish striking, and increased wear on the train. Before the movement is reassembled, the mainspring must be fully cleaned, dried, and lubricated so it can deliver smooth, consistent power. If you have not yet cleaned the rest of the movement, see our guides on deep cleaning plates and wheels and pegging lantern pinions and bushings.

How to Clean a Clock Mainspring

Preparing the Spring for Cleaning

The mainspring is removed from the movement or barrel and laid out on a protected surface so the coils can be accessed safely. A sheet of newspaper or similar material prevents kerosene and loosened dirt from staining the bench. Only a small amount of kerosene is required, and a small piece of scourer pad is sufficient for the entire job. Gloves are recommended because kerosene will transfer to the hands during cleaning.

Applying Kerosene With a Scourer Pad

A small piece of scourer pad is dipped lightly into kerosene and then squeezed so that it is damp rather than dripping. The pad is folded over the mainspring so that both sides of the metal are in contact with the abrasive surface. Cleaning begins at the outer end of the spring, where access is easiest, and the pad is worked back and forth to dissolve and lift away old grease, hardened oil, and accumulated dirt.

Cleaning the Full Length Without Distorting the Spring

The pad is worked progressively along the length of the mainspring. As the coils tighten toward the inner end, it becomes tempting to pull the spring outward to gain more access, but this must be avoided. Pulling outward risks “pyramiding” the spring, changing its natural curvature and causing it to cone or stack when wound. Cleaning continues only as far as the coils safely allow, working kerosene and abrasive into the accessible areas without forcing the spring open beyond its natural shape.

Drying the Mainspring After Cleaning

Removing Residual Kerosene and Dirt

When the entire accessible length of the mainspring has been scrubbed, the kerosene and loosened contamination must be removed. A clean cloth is folded over the spring and drawn from one end to the other. This first pass usually shows a surprising amount of dark residue. A second clean cloth is then used to repeat the process, wiping the mainspring thoroughly until no further dirt appears. The mainspring must be completely dry before lubrication is applied.

Inspecting the Cleaned Surface

After wiping, the mainspring is inspected visually along its full length. The surface should appear uniformly clean, with the original metal finish visible rather than a dull coating. Any remaining dark patches or areas that still feel greasy indicate that more cleaning is needed. In those cases, the kerosene and scourer process is repeated locally, followed by another careful wipe with a clean cloth.

How to Grease a Clock Mainspring

Choosing and Applying PTFE Grease

Once the mainspring is completely dry, it is ready for lubrication. PTFE grease is preferred for clock mainsprings because it provides long‑lasting, low‑friction performance without attracting dirt. A toothpick or similar fine applicator is used so that the amount of grease can be controlled precisely. The grease is applied only to one side of the mainspring. When the spring is later wound, the coils slide against each other and transfer the grease naturally to the opposite surface.

Working the Grease Along the Length

Lubrication typically begins at the inner end of the mainspring. A small amount of PTFE grease is picked up on the toothpick and drawn along the metal in a continuous line. As the spring is worked outward, the toothpick is reloaded as needed so that the line remains consistent. The goal is an even, thin coating rather than heavy blobs. Once the full accessible length has been treated, the mainspring is inspected to confirm that no sections have been missed.

Ensuring Even Distribution

When the mainspring is wound back into the barrel or onto its arbor, the coils press together and slide over one another, redistributing the grease into a thin, even film across both sides. Any excess tends to be pushed toward the edges, where it can be wiped away if desired. The important point is that no portion of the mainspring is left dry and that the overall layer is not so thick that it becomes a drag on the movement.

Storing or Reinstalling the Lubricated Mainspring

Temporary Storage Before Reassembly

If the movement is not being reassembled immediately, the lubricated mainspring should be stored in a way that prevents confusion later. Each mainspring is identified according to its function in the movement, typically as time train, strike train, or chime train. The spring can be wound, secured, and placed in a labeled bag or container so that it cannot be mistaken for another mainspring during reassembly.

Reinstalling the Mainspring in the Movement

When the clock is ready for reassembly, the mainspring is installed back into its barrel or onto its arbor according to the movement design. As it is wound, the earlier application of grease is spread evenly across the working surfaces of the coils. A properly prepared mainspring will deliver consistent power to the great wheel and through the entire train.

Why Proper Lubrication Is Essential

A mainspring that has been thoroughly cleaned and correctly lubricated is fundamental to the long‑term health of a mechanical clock. Even if pivots, bushings, and wheels are in excellent condition, a dirty or dry mainspring will weaken the movement and cause erratic performance. Regular mainspring maintenance during complete overhauls reduces friction throughout the train, improves timekeeping, and minimizes wear on critical components.

FAQs

How often should a mainspring be cleaned?

A mainspring should be cleaned and lubricated every time a movement is fully serviced. Old grease hardens over time and becomes abrasive.

Can I oil a mainspring instead of greasing it?

No. Oil does not provide the necessary film strength and will migrate away from the coils. PTFE grease is the correct lubricant.

How do I know if a mainspring is too damaged to reuse?

If the spring shows cracks, distortion, or signs of metal fatigue, it must be replaced. A damaged mainspring is unsafe and can fail violently.

Should both sides of the mainspring be greased?

No. Greasing one side is sufficient. The winding action distributes the grease evenly across both surfaces.