How to Use an Ultrasonic Clock Cleaner

Another  interesting note from a customer:

“Don’t knock my smock or I’ll clean your clock” was a panel line in a Calvin and Hobbes cartoon strip. As one who repairs antique clocks I checked the origin of the phrase and found that it usually signifies a violent encounter. Not a good idea when dealing with a customer’s heirloom time keeper.

Most of the clocks I clean and repair have brass works – the gears and frames – along with steel parts such as verges, spindles, spacers and springs.  In my early days cleaning these parts after disassembly entailed dipping them into a solvent and using a soft brush to work away grime and dried lubricants.  A messy process indeed, and not that satisfactory in terms of results.

An ultrasonic cleaner has proven far more satisfactory, but when using this technology for clocks and watches care must be taken not to damage the parts.

In a sense this method to “clean your clock” can be equated to a “violent encounter.” My compact Elma ultrasonic cleaner obtained from Tovatech is powered by transducers operating at 37 kHz – above the audible range – that are attached to the bottom of the cleaning tank containing the cleaning solution.   Disassembled clock parts are placed in the supplied basket and immersed in the ultrasonic cleaning solution. When I turn the unit on the transducers create billions of minute bubbles that implode when they contact parts in the cleaning basket.  The implosion, called cavitation, creates shock waves on a microscopic level that quickly blast off grime and dried lubricants while leaving a nicely polished surface.

Proper solutions and proper energy levels are important when using ultrasonic frequencies to clean clocks and watches.  For example, water-containing solvents should never be used when steel parts are in the basket.  And while ammonia-containing solutions are great cleaners – especially for fancy watches and watch cases – they should not be heated as they give off vapors.

As a further caution, parts should be kept in the ultrasonic bath only as long as necessary to complete the cleaning process. Energy levels must be low enough to avoid cavitation damage to soft brass clock parts or delicate watch parts.


Please share your experiences in using ultrasonic energy to increase efficiency in your operations.  What system or procedure did it replace?   How have you “tweaked” the cleaning process to improve results or throughput?

About Rachel Kohn

So how did an MIT Ph.D. end up selling refrigerators? When I figured out that a lot more scientists buy lab refrigerators than innovative leading-edge instruments. I hope that my many years of lab experience will help you find the right equipment for your work. Before co-founding Tovatech I worked in business development and project management at Smiths Detection, Photon-X, Cardinal Health, and Hoechst Celanese. And before that I spent 12 years as an R&D chemist at Hoechst Celanese and Aventis working on advanced drug delivery systems, polymer films and membranes, optical disks, and polysaccharides. Some day, eventually, I’ll make enough money to develop an innovative technology that will change the world. Read More