Ultrasonic cleaning fluids are used for getting rid of all the grime and dirt that accumulate on the surface and in the crevices of jewelry. So, they always contain a surfactant or a good wetting agent to increase cavitation – a process that creates millions of tiny imploding bubbles that are responsible for the cleansing action of the cleaning solution.
There are several ingredients used in the production of the cleaning fluid to optimize the process of ultrasonic cleaning. They primarily assist the process of breaking the chemical bonds between the soil and grime and the surface of the metal or the object being cleaned. Several manufacturers sell different formulations subject to the intensity of cleaning and the type of material that is to be cleaned.
The cleaning fluid typically contains application-specific compounds and appropriate wetting agents, reactive components and detergents. It is important that you pick a cleaning fluid that matches your requirement as closely as possible to avoid possible damage due to the fluid’s undesirable cleaning action. When in doubt try it on a small piece of jewelry first. You can also ask your jeweler and verify that the cleaning solution will not have an adverse reaction with your jewelry. Most ultrasonic cleaning solutions for jewelry are soap based aqueous solutions and as a general rule of thumb will be non-reactive with most jewelry. That said, there are certain gemstones that should never be cleaned in ultrasonic cleaners because of their fragile quality. Check that your gemstones do not fall in this category.
The cleaning fluids meant for jewelry are basic in nature, with a pH of around 13. They are water soluble and are comprised of isopropyl alcohol, sodium hydroxide and disodium cocoamphodiacetate. The resulting solutions contain seventy to eighty percent water by volume . They also have a detergent-like odor. Normally a cleaning fluid with such a composition is safe for use as an ultrasonic cleaning solution.
The ultrasonic cleaning solution must never be made of flammables or liquids with low flash points. The process of cavitation in the cleaning tank during ultrasonic cleaning produces a spike in the temperature. This is because it releases energy that is quickly converted into kinetic and heat energy. The by-products of bleach, acids and bleach, aluminum and oxidizing agents should never be used. These agents are probably unsafe and get readily ignited at the operative temperature of the ultrasonic cleaner. Their usage also results in extensive damage to the cleaning tank, which is the primary component of the ultrasonic cleaner. So, the best way and perhaps the only to use these agents without causing any potential harm would be in a suitable cleaning container such as a glass beaker.
It is also not necessary to replace the cleaning fluid after each and every wash cycle. A fresh cleaning solution is needed only when there is a a gradual decrease in the cleansing activity of the liquid with the increased number of uses or when it appears visibly spent or dirty.
This article was written by Dr. Bob Sandor, a Director at Tovatech, a leading North American supplier of ultrasonic cleaners. When not busy running his company, he explores his fascination with the many aspects of various scientific & industrial devices. For more information on this article visit the Tovatech site from any of the above links.