Seth Thomas Adamantine time and strike mantel clock
Seth Thomas Adamantine time and strike mantel clock

I am servicing the first antique clock I ever bought. After having serviced many others it is time to give this clock a little love.

Some years ago (2000) my wife and I were traveling around Nova Scotia and stopped in a little village called Blockhouse. We found an antique store, walked in and never intended to buy an antique clock that day but left with an American Seth Thomas Adamantine mantel clock. It looked like it was worth many  more times than we paid for it. We left the store thinking we had stolen it.

My research revealed that thousands were made and the price we paid at the time likely reflected its true value. The clock came home and sat on top of our piano and looked great. For a couple of years I wound it up religiously and marveled at its beautiful marbleized case and the sound of the gong on the hour and the bell on the half hour. I stopped winding it, let it sit on the piano and ignored it. About 5 years ago as I began to build my collection of vintage and antique clocks I wound it up and have kept it running ever since.

These clocks have become known to collectors as “Black Mantel Clocks”, and were popular from 1880 to 1931. Adamantine veneer was developed by the Celluloid Manufacturing Company of New York City, and was covered by U.S. Patent dated September 7, 1880. Seth Thomas Clock Company purchased the right to use the Adamantine veneer in 1881. At that time Seth Thomas stamped the year of manufacture on the bottom of each case. Though somewhat difficult to read the date on this particular clock is 1907.

Re-assembled and tested
Re-assembled and tested

Each clock I added to my collection needed some work and so I left the ST thinking that one day I would service it. Despite the fact that I kept it oiled, displayed it in a relatively dry dust free environment, it needed a good cleaning and a little bushing work.

Once you take a movement out of its case you begin to discover it’s little secrets. I immediately noticed a stripped speed regulating gear. The regulator arbour runs through the plates and is connected to the pendulum hanger to slow or speed up the clock. The rate adjustment is on the front of the clock and the smaller end of a double-sided key is used to speed and slow down the clock. I observed a rate adjustment screw on the pendulum bob. The “newer” bob had evidently been added at some point in the clock’s life to replace the stripped gear. The other possibility is that it might have had both. I have seen French clocks with both a front rate adjustment and an adjustable bob.

Regulating arbour
Regulating gear is stripped

The movement was taken apart and the parts were cleaned in an ultrasonic cleaner.

Back of movement
Back of movement showing

Bushing wear was not an excessive but enough to justify installing 4 bushings; S2 front, T2 front, and escape wheel, both front and back plates. Putting the movement back together is relatively easy though it is always frustrating positioning the helper springs and levers in place as you move the pivots into their holes. It takes me a few attempts to get the strike side gears and levers correctly aligned. The stop wheel, stop lever, maintenance lever and count wheel hook take a little trial and error and it not something I have managed to get right the first time.

Seth Thomas clock face
Seth Thomas clock face

Once back together the movement was oiled and placed back into it’s case. It should  run reliably for years to come. Save for a slight aging of the clock face the clock is in excellent original condition.

Antique Seth Thomas Adamantine clocks look great on any mantel.

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