Seth Thomas Red & Black Adamantine Mantel Clock

This Seth Thomas Adamantine mantel clock is dated March 1901 on the case bottom (date code 1091C). The case is 12 1/8 inches tall, 17 5/8 inches wide at the feet, and the minute hand is 2 1/8 inches long from center to tip.

See more photos.

Adamantine is Seth Thomas’ patented process of applying colored celluloid to wood clock cases.

The movement has a recoil escapement located at the rear. (This is the first type of movement used in Adamantine clocks, and was phased out and replaced with the No. 89 movement around 1900 – 1901. March 1901 is the latest use of the rear-escapement movement that I have seen).

This clock has a metal dial with cutouts though which the numerals on a paper dial can be seen. The regulator is above the numeral “12”. (Clocks with No. 89 movement have the regulator below the center of the dial.)

This movement uses loop-end mainsprings that are 11/16 inches wide. This clock has the original mainsprings. The time spring is 0.018 inches thick, and the strike spring is 0.019 inches thick. If the springs neededĀ  replacing, I would use 0.0165 inch thick springs. The original springs in this this clock were fine, so I cleaned and reinstalled them.

Here is a video of the escapement, and the clock striking:

Repair job 5369.

Share this post:


One comment

  1. Job 5369 Any idea what this clock would be worth? I have the same clock, date and movement. It is in great working order (recently serviced) and keeps perfect time.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.