Cleaning watch movements.

Face plate of a movement by the
Lancashire Watch Co before cleaning

I was recently asked on Facebook how I cleaned the particularly dirty watch movement shown, that reply whilst covering the essentials was necessarily brief so here is the full story.

The obvious thing to do and the recommendation of most books on watch maintenance for the amateur, is to use metal polish and indeed this in combination with other techniques will work and can be a quick way of getting the top plate of a movement clean and shiny [see this later post for an example], however there are some significant disadvantages firstly it is purely a cosmetic exercise not getting into the nooks and crannies of the watch or helping with the cleaning of the critical moving parts and secondly there is a real risk or removing the gilding from a gilt movement or the often very thin nickel or other coating frequently found on Swiss watches. The better method is not cheap as it requires the purchase of special cleaning and rinsing fluids and an ultrasonic cleaner cleaner.

The fluids are designed to allow the cleaning of “complete movements” as it says on the label. I do not think this is a good idea for old pocket watches, particularly those with motor barrels that can not be removed without taking the movement to pieces, as the fluid will interact with the oil in the barrel making it ineffective and judging from a few movements I have had in that have been done this way and from my experience with leaving too much oil on the movement before cleaning, it is likely to cause bad staining of the movement as the mixture spreads over the watch. In any case if the movement is to be cleaned properly then it needs to be taken to pieces so its best to do that up front.

This is the way I do it:

 

The same LWC movement after cleaning

 1. The movement is first broken down into its major parts, the top plate being removed together with the train, escapement and motor barrel. I leave the winding and setting gear in place if it is fixed in as the components are too small to easily handle. The mainspring is removed from the barrel.

2. Any obvious oil on the plates, barrel etc. is removed with tissue or a cloth, then loose material removed with a tooth brush with some mentholated spirits if necessary to get rid of thickened oil and other significant deposits. 

3. Everything goes into the cleaner for 10 minutes. Whilst ultrasonic cleaning is a relatively gentle process it does lighten gilding a little, particularly on very old watches, and it is best not to over do it, a really dirty piece might get and extra five minutes but no more. 

4. Pieces are then put into a rinsing fluid to get rid of the solvents and to chemically remove any water that might be present. After patting dry with tissue and blow drying the hairspring they are left to dry before the next stage. 

At this point it is worth mentioning one additional cleaning problem that may have to addressed. Sellers of old watches, on eBay in particular, are eager to be able to describe them as “working” or “ticking” so are liable to soak them in oil (lengthening part 2 of the cleaning process) to get them moving and occasionally spraying the whole movement with WD40 or similar. The later process will undoubtedly cause the hairspring to get coated in oil, the former will only probably do so. This will mean that although the watch may tick the coils of the hairspring will stick together and if the watch runs for more than a few seconds it will typically run  fast and erratically. The same effect may happen naturally over a very long period through corrosion or leakage of oil from the barrel. In both cases it is unlikely that the ultrasonic cleaning will be enough and it will be necessary to resort to some very strong solvents to clean up the hairspring.  

5. Some of the winding gear may be removed for inspection at this stage and, particularly on some English keyless movements, to allow easier reassembly of the movement.

And the top plate of the same.

6. As the movement is put back together everything gets a final hand cleaning with a toothbrush which should remove any lingering pieces of crud and in particular fluff and hairs which frequently get wound up in the wheels. Smoothing broaches, peg wood and other implements are also used to make sure jewels, pivot holes etc. are clean. This is also the time to visually check that everything is complete, undamaged and the correct shape.

7. After reassembly the movement is wound and immediately put onto the escapement analyser to make sure that the new mainspring is not over strong which among other things threatens to break the impulse jewel if the balance wheel turns by more than 360 degrees.

Some watches may run well immediately and can be given an initial regulation, using the analyser, and adjustments to get it into beat and to reduce any positional errors, others will take their time to get going but all need to run for 24 hours before going on the analyser again. If I am fortunate that will be the movement done, if not it could mean a lot of work making repairs, fiddling with the hairspring, etc.