Cleaning Nasty Stainless Steel Watch Bracelets With an Ultrasonic Cleaner

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You don’t want to put a clean, fine-tuned watch movement into a grimy, crusty case. Aesthetics aside, the gunk and grime can flake off into movement or eat away at the materials.

A couple people asked me about ultrasonic cleaning. I’ve mentioned using one a few times in recent posts, so here’s more information about using an ultrasonic cleaner to tackle what would otherwise be a gross and tedious task: scrubbing a stainless steel bracelet.

Our Patient

A friend of mine asked if I would resize his watch—here it is.

A few of this blog’s regular readers might be horrified. Yes, this is a huge fashion watch: a 44-mm Hugo Boss with a quartz movement. But I’ve always said that a “nice watch” is one that someone is willing to maintain and repair. eBay is full of fine watches that people unload at the first sign of wear and trouble.

This watch has the hallmark of a watch worn daily: a gloppy film of grime. Here’s the clasp.

The ends of the links have a caked on layer of black paste, a melange of skin, sweat, bacteria, and other good stuff.

Before resizing the bracelet, we really ought to clean it.

Ultrasonic Cleaners Will Change Your Life

Enter the ultrasonic cleaner. These machines have been around a long time. The principle is to place parts in a fluid and then cavitate the fluid. This creates bazillions of small bubbles that collide with the piece, scrubbing it. Because the piece is immersed in fluid, the cavitation process can clean crevices, recessed areas, and intricate designs.

Here’s the one I use.

If you get an ultrasonic, it is worth paying a bit more for one with a heater. Heating the cleaning solution vastly improves the quality of the cleaning. The timer knob controls the length of the cleaning cycle; the heater knob controls the temperature of the solution. It takes a while to heat up, I’ve found. I usually clean steel parts at a toasty 140 degrees.

Your three big variables are (1) length of the cleaning cycle, (2) the fluid’s temperature, and (3) the cleaning solution itself. Browsing a jewelry supply webpage will show you all kinds of options for cleaning solutions based on what you’re trying to clean.

Nearly all of my work involves cleaning stainless steel parts, and I’m usually trying to remove residue from polishing compounds. An old-timer in metalworking recommended Simple Green for this. Diluted 1:1 with distilled water, this simple home brew does an amazing job with steel parts. (Don’t use it on anything with paint, enamel inlays, or adhesives!)

And it looks eerie and intriguing, too.

One rule of ultrasonics is to suspend the parts—you can’t let anything skitter around on the bottom of the tank. One way is to use a mesh basket, shown in the picture. This works well, but I avoid it for nicely polished parts. The metal pieces will rub on the metal basket, potentially creating micro-scratches.

Instead, I use plastic-coated frames, like this this old fellow. You can suspend cases, bezels, bracelets, and case backs without them getting scuffed.

It’s worth getting rubber-tipped tweezers for handling the parts, which will be hot. (I have heard, from anonymous and abashed sources, that if you ineptly drop a plastic tube into the first cylinder chamber of an inline-4 Saab 9-3 engine, that these these long tweezers can retrieve it. Just food for thought.)

An ultrasonic will make short work of this bracelet. I just dropped it in with no pre-cleaning or scrubbing or wiping. Cleaning a bracelet like this with a soft toothbrush and hand soap, for example, would be gross and tedious. Each link would need to be exposed and scrubbed on all sides. But even after that, the gunk in the crevices (e.g., the link pin holes) would be hard to remove.


After around 10 minutes, the bracelet was squeaky clean. All the gunk is gone from the pin holes.

The clasp and link ends are pristine.

And the ends of the links, seen when folded, no longer have the black biohazard paste.

Again, this was a low-effort cleaning—put it in the ultrasonic, rinse it with clean water, and hand dry the parts.

When you’re using buffing wheels and polishing compounds, ultrasonic cleaners are an ideal way to remove compound residues after each step. When you scrub with a cloth or toothbrush, you’ll struggle to remove the residue from cracks and crevices, and the soft brush will itself create micro-scratches. The ultrasonic, in contrast, will remove the residue and leave the piece ready for the next step.