Tortoise Shell Finish Seth Thomas Adamantine Mantel Clock

Here’s an Adamantine Mantel clock (made by Seth Thomas) that I’d never seen before! I would describe the case finish as “tortoise shell”. Below are photos of the front of the clock, a closeup of the case, and a photo of the rear showing the movement:

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Adamantine is a veneered celluloid finish made by Seth Thomas Clock Company with various colors formed in the celluloid veneer. Common colors are black, mahogany and green; other colors such as white and various marbleized colors were also made.

(I taught my customer how to polish this case,  and he did the polishing and I repaired the movement.)

This clock doesn’t have a date code on the bottom of the case, but I estimate it was made ca. 1910. It is 11 7/16 inches tall, 12 15/16 inches wide at the feet and 12 3/4 inches wide at the top. The minute hand is 2 1/8 inches long, and the dial is celluloid-covered paper.

Repair job 6621. I polished the pivots, installed 14 bushings, and replaced the click rivets to make the winding reliable.

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One comment

  1. I enjoyed your article. I came across it trying to learn how to re-affix
    slightly curled up Adamantine on a clock (Seth Thomas @ 1900)I just bought on eBay. Where the face of the clock meets the base a small chunk of veneer at the edge is missing but the big concern is from that point to the other edge of the face the veneer is curled up just slightly. Do I attempt to somehow soften the veneer before floating a thinned Elmer’s glue under it and clamp with a waxed paper covered clamping strip? Is softening possible or even advisable. Will it likely crack? Another thought was to float a gap filling glue under the area and after wiping up the excess just let it dry. That way it would be held in place and not flex when being cleaned. The curl is so minor it wouldn’t look like a hatchet job, I tell myself. I could send a picture if feel like taking the time to offer advice.
    Thank you for your time.

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