Saturday 23 July 2016

Restoration of a French Black Marble/Slate Clock

This clock was in rather a sorry state having been sat in a damp environment, and had not been working for a few decades. None the less it has sentimental value to the owner, who wanted the clock to be restored throughout. These black cases can be challenging to restore depending upon the fading and oxidation. 




A closer picture shows that the clock has a Brocot Open  Escapement. This is an attractive feature on a clock such as this, adding an interesting element to its aesthetics. Though the escapement parts, not to mention the dial and bezel parts, are in an ugly state of tarnish, dirt and repair. The door has broken away from the bezel, and has been lost.



The case gave a good indication of what sort of state the movement was likely to be. This is a French movement by Samuel Marti & Cie, Paris. Typical of the movements made by French movement manufacturers of the time, who generally produced movements of good quality. That said, in my experience, I have often found that the main wheel/spring barrel arbour pivot surfaces on French movements can tend to fall short in terms of a quality finish, compared to the other pivot surfaces.



The movement in this clock has a great deal of corrosion on the steel arbours, pinions and pivots. Hidden under a layer of dirt and grime that is. Clear evidence of rust on the winding squares foretold a story of corrosion through out. I would strongly discourage the use of 'off the shelf' rust inhibitors that can be bought from vehicle accessory shops. These are likely to leave a hard black layer of black oxide on the surface of the steel, which can be extremely difficult to remove. Evaporust was used on this movements, along with plenty of brushing, followed by polishing. 

All the usual service jobs were carried out once the parts were in a better state, as well as other repairs which included the need to re-pivot the escapement wheel arbour. The pivot was corroded beyond resurfacing, polishing and burnishing. The escapement required new pallet jewels fitting and setting up. The anchor on which the jewels are mounted in the open escapement had had its span widened inappropriately before now, and also the adjuster that changes the depth of the pallet jewels into the escapement wheel had been abused with an incorrectly sized screw driver and the groove was partially destroyed. Adjusting the depth was a challenge. 





After much work  the movement was up an running on a test stand, and I could turn my attention to the case. Much time was spent thoroughly cleaning the case. Painstaking was the removal of hardened grime in the recessed detail ornately carved into the case. Once the case was thoroughly clean and the top re-cemented back on, a few layers of pigment were applied, buffed and waxed. This took two coats of pigment, in a few places three. Once this was complete I was able to hand pain gilt lacquer back into the recessed detail, which finished of the case nicely. I sourced a replacement bezel and door, plus a replacement grommet for the winding hole.

Overall the clock came out well, with a great deal of work, and the sentimental value could be enjoyed again.