How effective is your ultrasonic?

By Oliver Passe

Your ultrasonic cleaner is one of the key players in your jewelry shop, always standing by to remove polishing compound from a ring after re-sizing or to clean the schmutz off a client’s tennis bracelet. But how do you know if your ultrasonic is performing to Olympic-gold-medal standards? The answer can be found in a piece of candy—Mentos, to be specific.

This small Brazilian candy treat has a staggeringly consistent coating particle size, uniform white boundary layer, and unit weight. More important, the semi-soft translucent sugar center has a unique property that closely resembles the cocktail of jeweler’s rouge, cosmetics, perspiration, solids, and fatty resins found in a typical ultrasonic.

To use the tasty candy to determine the effectiveness of your ultrasonic, place one fruit-flavored Mentos tablet in the tank. Use a stopwatch to measure the time it takes the ultrasonic cleaner to strip the colored hard candy shell down to the translucent sugar core. An optimized ultrasonic cleaning system working in the 37kHz to 40kHz frequency range should easily do this in less than 50 seconds.

If your ultrasonic fails the Mentos test, you may need to make some adjustments. Try lowering the temperature to below 135°F/57°C for more powerful cavitation, clean out the tank (never let schmutz build up on the bottom), and refill the tank with fresh ultrasonic cleaning solution.

Oliver Passe is managing director of Nventa Inc. in Scottsdale, Arizona.