HAPs — hazardous air pollutants, VOCs — volatile organic compounds, ODCs — ozone depleting chemicals. What do you think of when you see these acronyms? Probably the first thing that comes to mind is your favorite cleaning and degreasing solvent. The next thing is regulations, lots of regulations that may be giving you a cause for concern. If this is so, take some comfort in the fact that you are not alone.

Companies throughout the U.S. are in the process of eliminating their use of traditional solvents such as trichloroethane (TCA), trichloroethylene (TCE), perchloroethylene (PCE), chlorofluorocarbons (CFCs, e.g. Freon TF, Freon-113, CFC- 113), methyl ethyl ketone (MEK), acetone, toluene, xylene, and methylene chloride as these solvents become subject to more stringent regulations.

With all the attention focused on these solvents and efforts to reduce their use, it seems appropriate at this time to pause and take note of the accomplishments that have already been achieved by companies in the US to find alternatives. Over the past few years, numerous companies have been actively looking for cleaning and degreasing alternatives and many have made considerable progress, as reported in pollution prevention plans.

By sharing their successes, as well as providing some general guidance, we hope to help some of you in your efforts to find alternatives also.

As you conduct your search, however, realize that there are neither quick and easy solutions for your cleaning challenges nor “drop-in” replacements for your traditional solvents. As we all know, these traditional solvents have been widely used because of their excellent cleaning performance in diverse cleaning applications. Alternative cleaners or cleaning methods, by contrast, typically have limited applicability, and the following approach can be taken when searching for alternatives.

First, take a good, in-depth look at your current cleaning processes to understand what you are cleaning and why. Cleaning is the process of removing soils or contaminants from the surface of a substrate, and things to look at in your evaluation are:

• the substrate materials (e.g. metal, plastic),
• the specific soils to be removed (e.g. particulates, metal fines, oils, adhesives, waxes, rosins, greases, glycols, inorganic salts),
• how the soils are introduced onto the surface,
• the cleanliness requirements or standards, and
• the size and configuration of the parts.

Once you understand what you are cleaning and why, next, decide if there is really a need for cleaning. You may be surprised to find that you don’t need to clean as much or at all, as was the case with Hughes Missile Company, who conducted a thorough review of their microelectronics assembly cleaning processes and determined that a considerable amount of cleaning with TCA had no effect on product reliability and thus could be eliminated. Similarly, Intel Corporation found that cleaning with Freon in some operations could be eliminated.

Next, consider changes that will eliminate or minimize the need for cleaning, such as process changes equipment modifications, material substitutions, or product redesigns or reformulations. One company  installed an enclosed, automated casting machine and high efficiency gelcoat spray guns for manufacturing cultured marble, replacing a cement mixer, plastic buckets, and paint brushes, and as a result, significantly reduced the quantity of acetone used for equipment and tool cleaning.

Intel Corporation converted from ink markings of logos on some finished packages to laser marking, and eliminated the need for package pre-cleaning with Freon. One manufacturer of structural composite honeycomb core, found that by implementing improved materials handing procedures, such as wearing gloves and using plastic covering, a final cleaning of the core with TCA to remove particulates and body oils could be eliminated, while still meeting customer specifications.

McDonnell Douglas Helicopter switched to a water-soluble drawing and now uses our aqueous cleaner instead of TCA. Another company switched to a Kester water-soluble fluxes for solder assembly operations and now cleans with a water-based cleaner instead of Freon.

Once you have done everything to eliminate or minimize cleaning requirements, next consider using a less toxic material or cleaning method for each of your specific cleaning applications. In general, alternative cleaners or methods include aqueous, semi- aqueous, and nonaqueous cleaners, and mechanical and thermal cleaning methods.

Aqueous cleaners are waterborne solutions that typically contain rust inhibitors, surfactants, or emulsifiers, and include acid, alkaline or neutral cleaners. These cleaners are generally used for wipe cleaning, or in enclosed parts washers, spray tanks or immersion dip tanks, and are followed by a water rinse stage, and sometimes a drying stage.

Semi-aqueous cleaners consist of water-immiscible solutions used in conjunction with a water rinse and include terpenes, esters, petroleum hydrocarbons, and glycol ethers. Nonaqueous cleaners do not require the use of water in the cleaning process and include high flashpoint hydrocarbon or nonchlorinated cleaners, such as stoddard solvent, kerosene, or mineral spirits, as well as alcohols such as ethanol, isopropanol (IPA), and methanol and hydrochlorofluorocarbons (HCFCs). Mechanical and thermal cleaning methods include dry abrasive cleaning with plastic media or sandblasting, and bake-off ovens.

Overall, the use of alternative cleaners or cleaning methods seems to be the preferred option for many companies in the US. A printed circuit board company replaced TCA and Freon used for removing flux from printed circuit boards with an Alpha Metals saponified aqueous cleaner. A Plating company replaced TCA used for degreasing brass and steel parts with Industrial Metal Cleaner #10, an alkaline cleaner that can be used in spray or dip applications.