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Finding A Solvent Solution That's Right For You

July - 2008
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In the finishing industry, solvents are primarily used for parts cleaning. Many of these, such as trichloroethalene (TCE), can be advantageous in that they are fast acting and quick to evaporate, which minimizes drying time. On the downside, these same solvents can be extremely toxic, carrying the health risks of liver and kidney damage, neurological disorders, and even cancer. They are also culprits when it comes to soil and water contamination, and other areas of environmental degradation. So what is a finisher to do? The good news is that an increasing number of alternatives to traditional solvents are appearing across the spectrum, making it easier to safeguard your worker’s health and the health of your community.

Where do I begin?
The mounting government crack down on non-reusable or non-recyclable solvents is a good enough reason in and of itself to start rethinking and minimizing the use of solvents in your operation. But where to start? The easiest first step is the first step of any ‘sustainable’ approach; that being to reduce wherever possible. If you can use less of any hazardous substance, then make sure to do so.

Once you’ve filtered out what can be reduced, it’s time to focus on what can be replaced. It is important to first go through and identify the uses and volumes of solvents you have in your facility, which will allow you to determine which ones should and can be substituted with something else. Examine your current stock of solvents, keeping an eye out for those containing chemicals or compounds that may soon be phased out. You should ask yourself the following questions:

1. What are the parts that need to be cleaned?
2. What contaminants are being removed during the cleaning process?
3. Why are these parts being cleaned? (In some instances, it may turn out to be an unnecessary step and expenditure)
4. How can I stop contamination at its source, prior to the need for cleaning?
5. To what degree must the parts be cleaned?

After you have answered these questions, you can apply this knowledge to your quest to find the most functional and effective alternatives.

Alternatives to Consider
There are several popular and cleaner alternatives to solvent cleaners available to finishers today. One of the most popular is water-based cleaning, also known as Aqueous cleaning. Various processes to remove contaminants include the use of acidic and/or alkaline aqueous solutions, as well as immersion, pressure spray and ultrasonics. A compromise between solvent use and aqueous cleaners is what is known as a Semi-Aqueous cleaner: a semi-stable mixture of water and solvents (or ‘emulsions’). These are often used for removing waxes, heavy greases, tar and baked-on organic materials.

Carbon Dioxide (CO2) Blasting is another option that consists of two main technologies: CO2 Pellets and CO2 Snow. The Pellets combine solid CO2 and a gas to strip paints and to remove grease and oil, whereas the CO2 Snow relies on flakes of frozen CO2 to clean surfaces. Another cleaning alternative is Supercritical Fluids. Lacking in surface tension, these fluids can quickly and thoroughly dissolve contaminants, and are easy to remove. Yet another option is Media Blasting, which is a process that uses abrasive media (such as sand, glass beads, and more recently plastic particles) dispersed at high pressure against a surface to remove contaminants.

A great resource for finding comparable solvent replacements is the Toxics Use Reduction Institute’s (TURI) Surface Solutions Laboratory, (www.cleanersolutions.org). Here you will find the easy to navigate ‘Replace a Solvent’ page, allowing you to search for alternatives based on the solvent you wish to investigate, and then narrowing down your results by contaminant, substrate, and even equipment type. TURI is an especially helpful resource, due in large part to the fact that they actually test these alternatives, and rate them according to their effectiveness in application. Another good resource is the Integrated Solvent Substitution Data System (ISSDS) at http://es.epa.gov/issds.

Always consider the potential environmental impacts, health and safety concerns, solvency, flammability, cost, and stability of a solvent before choosing the right one(s) for your needs. Since there is no single ‘miracle solvent’ out there, be sure to evaluate each option thoroughly in order to achieve the best results, while causing the least negative impact to your workers, your community, and your environment.

By: Anna Levitsky, Editor of the Finishing Talk Newsletter
Contact: anna@finishingtalk.com