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How to Select an Ultrasonic Cleaning Solution

A1 Cleaning Solution

Selecting an ultrasonic cleaning solution is a critical part of getting desired cleaning results. When asked why we cite a familiar situation: When doing dishes, pots and pans after a meal we add a detergent to the dishpan or dishwashing machine to break up grease and other soils to yield a satisfactory result.

Ultrasonic cavitation (the cleaning action) can also occur in plain water but is far superior when an ultrasonic cleaning solution "detergent" is added to the cleaning tank.

Exactly What is an Ultrasonic Cleaning Solution?

These are usually in the form of liquid concentrates designed to be diluted in water. After all you would not pour an entire bottle of dish detergent in the dish pan. Unlike cleaning solutions such as trichloroethylene and perchloroethylene used in the past most of today's ultrasonic cleaning solutions are biodegradable and can be flushed down drains. (But check local regulations to be sure.)

These solution concentrates are formulated for specific cleaning operations but all have the function of making water wetter and making ultrasonic cavitation work faster and more efficiently to loosen and carry away contaminants. We provide specific examples later in this post. But first:

Types of Ultrasonic Cleaning Solutions

While a large variety of ultrasonic cleaning solutions are on the market, they can be broadly divided into three major categories based on their pH or degree of acidity or alkalinity with those at the midrange termed neutral.

By way of further explanation pH is a measure of hydrogen ion concentration. Aqueous solutions at 25°C with a pH below 7 are acidic; those with a pH greater than 7 are alkaline (sometimes referred to as basic). A pH of 7 designates neutral.

Within these categories ultrasonic cleaning solutions can be emulsifying or demulsifying. These two terms describe what happens to the contaminants when removed from surfaces being cleaned.

Emulsifying ultrasonic cleaning formulations

These formulations hold contaminants in suspension and are typically used for low-volume cleaning operations. Because oily contaminants remain in the solution rather than float to the top they build up over repeated cleaning cycles, begin to inhibit cleaning efficiency and, perhaps more important, may remain on the surfaces of cleaned products. This could necessitate post-cleaning rinsing operations.

Demulsifying ultrasonic cleaning formulations

Demulsifying causes oily contaminants to float to the surface of the cleaning solution where they can be skimmed off manually or by using cleaners equipped with weirs and spray bars for storage and later disposal.

The step serves two purposes:

It reduces the potential for floating contaminants to adhere to the product when it is removed from the bath and it helps prolong the useful life of the ultrasonic cleaning fluid.

Demulsifying formulations are typically used in high-volume cleaning operations.

Key Selection Criteria For Ultrasonic Cleaning Solutions

Now that you are familiar with basic types of ultrasonic cleaning solutions you can refine your selection based on the following 5 considerations.

  • 1.What is being cleaned
  • 2.The contaminants to be removed
  • 3.The product configuration
  • 4.What the product is made of
  • 5.Post-cleaning requirements if any

There can be other cleaning solution selection criteria but these will do for the purpose of this post. Now we'll get to some specific examples of these formulations and their uses.

Examples of Ultrasonic Cleaning Solutions and Uses

Alkaline Cleaning Solutions

Alkaline (a.k.a. caustic) cleaning solutions are exemplified by the elma tec clean A series of concentrates. Of these we bill elma tec clean A4 as a nearly universally applicable concentrate for just about every need in the lab and workshop. Diluted to 2 to 5 % with water and operated at a bath temperature of 50⁰C to 80⁰C it’s great for glass, ceramics, plastics, rubber and most metals except the lighter alloys. We recommend elma tec clean A4 to clean carburetors, fuel injectors, engine parts, newly machined parts, and similar components to remove smoke, grease, soot, wax, coolant oils, loose metal particles and dust.

For a milder version select elma tec clean A1 for glass, optical assemblies, ceramic substrates and electronics. We recommend it for cleaning printed circuit boards used in PDAs and similar devices. It safely removes soldering flux, oil, dust, water damage, coffee, tea, soft drinks, milk and fingerprints when diluted to 3 to 10% with water and operated at 40⁰C to 80⁰C (65⁰C for PCBs).

Another version, ammonia-containing mildly alkaline elma tec A2 is a good selection to remove oil, fat, grease, sweat, oxides, polishing compounds and similar contaminants from ferrous metals and non-ferrous brass, copper, bronze, precious metals and jewelry when diluted to 3% to 5%. Its ammonia content makes it especially useful for brightening brass and copper.

Acidic Cleaning Solutions

Acidic ultrasonic cleaning concentrates are used for tough cleaning jobs and can involve a chemical reaction to remove contaminants. Emulsifying elma tec clean S1 diluted to 1 to 5% removes oxide films, rust, lime, grease, oil, corrosion, and mineral deposits from nonferrous heavy metals, stainless steel, aluminum, light metals, brass, steel, plastics and glass.

Stronger acidic solutions are available for these materials along with steel, iron, gray cast iron, hard alloys, nickel, nonferrous heavy metals and precious metals. Remember to remove steel products immediately after de-rusting and rinse with an anticorrosive. Ask us about elma-KS for temporary corrosion protection during cleaning and rinsing cycles.

Neutral Cleaning Solutions

Elma tec clean N1 is phosphate-free emulsifying neutral cleaning concentrate for gentle cleaning action. It is used for the treatment of highly sensitive pieces to remove oil, grease and other organic particles.

While it is safe for all metals, plastics, ceramics, glass, and rubber it should be tested before using on magnesium. When used in an ultrasonic cleaner it is diluted to 2 to 5% with water. Without ultrasound dilute it to 10%. Contact iUltrasonic for more information on elma tec clean N1.

Special Purpose Ultrasonic Cleaning Solutions

As indicated above a variety of special formulations are available for specialized cleaning. Here are some examples:

Cleaning Medical and Surgical Instruments

There are strong governmental and professional association recommendations/requirements for cleaning medical and surgical instruments including cleaning and disinfecting or sterilizing.

Enzymatic concentrate MedClean C7 helps meet these requirements by cleaning medical and surgical instruments by removing blood, tissue, ointments, light oils and similar contaminants before disinfecting or sterilizing.

Cleaning Firearms

Ultrasonic cleaning procedures help public safety and military organizations, hunting and skeet shooting clubs as well as firearm collectors maintain performance of their pistols and rifles with regular sessions in an ultrasonic cleaner.

Two formulations available for firearm maintenance are GunClean L6 to remove powder residue, bullet shavings, hardened lubricants and other contaminants much faster and more thoroughly than using brushes or solvents.

After cleaning the firearm can be fully lubricated in a bath of GunLube L5 ultrasonic gun lubricant for protection against rusting.

Cleaning Jewelry

Removing dirt, grease, buffing compounds, rouge, tripoli and oxides from silver, platinum, jewelry and gems is accomplished by a bath in JewelryClean S8. But note that softer jewels such as pearls should not be cleaned ultrasonically.

A Caution on Flammable Ultrasonic Cleaning Solvents

Large-scale cleaning with flammable solvents requires explosion-proof or explosion-resistant ultrasonic cleaning equipment to avoid the danger of fire or explosions. It also requires that the location of the equipment and its operating procedures conform to national and local regulations.

On a smaller scale, however, and with special precautions benchtop units can be used to clean small parts. Parts can be submerged in a beaker containing the solvent. The beaker is lightly covered and placed into the ultrasonic tank filled with water and a surfactant.

Cavitation will occur outside and inside of the beaker, but the harmful chemical will not be in direct contact with the tank of the ultrasonic cleaning equipment.

Even with these precautions the ultrasonic cleaner should be located near or under an exhaust vent. Contact your local regulatory authorities or our experts for advice on cleaning with volatile solvents.

But if your operations require large scale cleaning with volatile solvents such as IPA, acetone or toluene contact us for information on the SOL-XP explosion proof equipment or the Elma X-tra LSM explosion-resistant ultrasonic cleaner along with information on how to comply with NFPA and related codes concerning hazardous areas.

Tips on Maintaining Ultrasonic Cleaning Solutions

As noted earlier in this post, contaminants removed during the cleaning process remain in the cleaning solution and eventually reduce performance.

While performance can be extended by the means suggested eventually the solution must be changed. Drain and dispose of it along with skimmed off contaminants according to local regulations. At this time take the time to clean the tank following the user manual. Then fill and degas fresh solution to continue your cleaning operations.

Contact our Experts for Advice

This post touches on some of the major considerations involved in selecting and using ultrasonic cleaning solutions. The scientists at iUltrasonic are available for more detailed advice that will help you select the correct cleaning equipment, cleaning solution(s) and operating procedures to maximize the efficiency of your operations.


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