STEP-5: CLEAN!
Most ultrasonics (in fact, all the ones I am aware of) do cycles of up to 480 seconds (see the timer display above), or 8 minutes. This is to prevent the ultrasonic transducer from overheating and burning out, rendering the device useless. In this model of cleaner, the default setting is 90 seconds, and each press of the SET button raises it to 180, 280, 380 or 480 seconds.
The mixed case cleaning solution is not caustic nor is it toxic, but it can cause skin irritation to persons sensitve to chemical exposure (not me!). The solution will also be hot enough to cause a scalding injury. With this in mind, add about 100-150 or so cases into the cleaning tub being careful not to splash any of the cleaning agent. I sometimes put up to 300 or more cases in at a time, and just repeat more cycles to achieve the cleaning level I desire.
In between cycles, I agitate the cases (mix them around) in the cleaning tub using a fork or something similar.
When running, the unit will emit a low buzzing sound, this is normal. Bubbles may form and rise to the surface, this is also normal. The cleaning agent will become discolored, and this is also normal...it is the dirt and filth coming off the cases and dissolving into the cleaning solution.
Ultrasonic cleaners are used in dentistry, jewelry work, automotive and marine industries, and a lot of other activities to clean solid objects inside and out. The transducers in the base of the cleaning tub create supersonic sound waves that travel thru the cleaning agent. When these sound waves hit a solid object (like the brass cases shown here), millions of microscopic bubbles form and immediately burst, creating a scrubbing action that removes dirt, filth, grease, oil, and sometimes even paint, from the surfaces of the object being cleaned. The forming and bursting of the bubbles is called "cavitation". These bubbles are not visible to the naked eye.
Now, a word of warning: DO NOT IMMERSE FINGERS OR HANDS INTO THE CLEANING TUB WHILE THE UNIT IS RUNNING. I have read many warnings about this, and my understanding is that the ultrasonic waves transmit thru the flesh and resonate in the blood, causing this cavitation to occur in the tissues, bones, and skin. Presumably, enough exposure will cause the bones to jellify, but I cannot confirm this. I have personally heard of no instances of injury resulting from the immersion of a body part into an operating ultrasonic cleaner, but that just means I have never heard of anyone immersing a body part into an operating ultrasonic cleaner. I value my limbs and my digits, and refuse to experiment on this. I pass along the warnings on the instruction sheet of the ultrasonic cleaner, without endorsement.
Photos below show the start of the first cycle of cleaning, and the end of the 3rd cycle of cleaning. Note how dirty the solution became.