Textile spot cleaning is not new by any means. It has been around for over 4 decades (that’s 40 years for those of you who don’t speak “decade”). Up until recent years, spot cleaning was a very simple operation. Take soiled shirt…Lay shirt on rag or cleaning station…Shoot jet of cleaning fluid through soil…Air dry shirt. Simple huh! Not anymore, things have changed. On April 10th 2000, the final phase of the new OSHA standard on Methylene Chloride became effective. This standard dramatically changes the way in which spot cleaning must be carried out.
For the uninitiated Methylene Chloride (also known as MEC and Dichloromethane), is the primary ingredient in most, and I mean most spot cleaning fluids. It is used for a very good reason, it works. No other chemical has been found, that is as effective as MEC for the removal of Plastisol and other textile inks. Up until recent years, MEC was a mildly regulated product. An established TLV (Threshold Limit Value) of 500 parts per million, meant that even the most careless spot cleaning, would not exceed the TLV. Over the past few years, there have been concerns about the health and safety implications of products containing MEC. Primary concerns have been the possible carcinogenic potential of these products. This is not just limited to spot cleaners, but also to adhesives, both aerosol and bulk, along with any other products that contain MEC.
The new standard, sets a mandatory maximum TLV of 25ppm, with an action level of 12.5 ppm. All businesses, no matter how few or how many employees they have, must comply with this new standard. Outlined below is a summary of the standard, which is actually over 250 pages in length.
The OSHA Methylene Chloride Standard FR 62:1494-1619 became effective on April 10, 1997 and has been phased in over a period of 3 years. The final action date of this standard is April 10, 2000. As of this date, all employers whose facilities have Methylene Chloride present, are required comply with the standard.
What does all this mean? Very simply put, to comply with the standard, the first step is to determine the exposure level of Methylene Chloride (MEC) to the employees in the facility. This is conducted by taking one or more personal breathing zone air samples. Monitoring can be accomplished in house or by an independent testing service. The simplest method. is to use badges that are worn by the employees on their collars for a typical 8-hour shift. These are similar to the radiation monitors worn by x-ray technicians. Once the test has completed the monitor is sent to a lab for analysis.
These badges can be purchased with the analysis pre-paid. It is essential to follow the manufacture’s instructions exactly to achieve an accurate test result. The correct monitor type is 3M-3520 Organic Vapor/ Monitor with back-up Section (Recommend Pre-Paid Analysis) available from Lab Safety Supply Tel. 800/356-0783 or direct from 3M Safety Division Tel 800/896-4223.
If the results are 12.5 ppm or below, then no further action is required (other than documentation of the test). If the results are above 12.5ppm, but are below the TWA (Time Weighted Average) of 25 ppm, and are within the STEL (Short Term Exposure Level) of 125 ppm, the employer must begin medical surveillance of the exposed employees. Medical surveillance. basically means having your employees who may come into contact with MEC in the workplace, take a targeted oral and physical medical examination, as outlined by OSHA. If exposure is in excess of the PEL (Permissible Exposure Limit) of 25 ppm and/or the STEL of 125 ppm then action must be taken within 60 days to comply with the standard. The complete standard including medical compliance information can be found on OSHA’s web site at: OSHA
“OK, what other options do I have” you ask. Spot cleaning fluids can be separated into three basic types. Firstly there are the non-flammable products based upon Methylene Chloride (highly effective). The second group, are flammable solutions. These normally contain a very high content of Acetone (sometimes they are 100% Acetone). The obvious drawback here is the flammability issue. As a cleaner, acetone does OK, however, you can expect a higher degree of color bleed (ink running into other parts of the garment).
The final group are the new kids on the block, utilizing one of two solvents. The first is 141B Dichlorofluoroethane, a product developed as a replacement for some of the previously phased out Freon products. As a cleaner it will remove some Plastisol screen printing inks, it does however, take more product to accomplish the operation and is classified as a class 2 Ozone depletor. The second solvent being utilized is Normal Propyl Bromide (NPB). This product is very new, with very little data available. It is currently unregulated, however there are a lot of reports floating around that question the health risk potential of this product, as well as showing it to possibly have up to 100 times the Ozone depletion potential, of some phased out Freons. Other disadvantages with these types of products, are their costs, typically about 50% higher than conventional spot cleaning fluids and more importantly, their questionable ability to do the job!
The final step to a safe spot cleaning operation is to look at the equipment being used. At the heart of any spot cleaning system is the Gun. Guns come in various sizes colors and performance characteristics. Which gun is best? The one that does the job for you. Don’t be fooled by manufacturer’s claims of 2000 or even 3000psi. All spot cleaning guns have the potential to develop very high pressures when the nozzle is sealed off and a pressure gauge attached. It doesn’t take a ballistics expert to know that at these claimed pressures, the fluid stream would cut through the fabric like Darth Vader’s light saber. The actual pressure of the fluid stream as it hits the fabric is between 40 & 60 psi. Do not think that this is not enough pressure to puncture your skin, it most certainly is. Always keep your body away from the fluid stream and never, never point the gun at anyone. Look for a gun that has good balance and an adjustable nozzle. The manufacturers warranty will tell you a lot about the quality of the gun.
Almost a necessity now, is a cleaning station. Because of the job that they have to do, high airflow is paramount. Airflow is measured in CFM (Cubic Feet per Minute); a flow of 500 CFM is an acceptable level for most shops. If your solvent is flammable, you must use an explosion-proof unit. The cleaning screen should be stainless steel, and sized so that you can lay the soiled area and surrounding fabric over the vacuum unit. If it is too small an area, the fluid will run out in the fabric and take longer to dry, possibly causing ringing or stains. If the cleaning surface is too large an area, then the fabric will take longer to dry, as the air will be diverted to other parts of the cleaning screen.
For the best protection look for units that offer complete vapor recovery. Exhausters with over-spray shields greatly help to reduce airborne contamination of the workspace. Some exhausters have integrated Activated Charcoal filtration that allow the unit to be vented into an open area inside a facility, allowing installation in large buildings where outside ventilation is not practical.
Is there any black magic in the chemical industry?…No. Do I have a magic wand that can make water do the job of spot cleaning solvents?… also, unfortunately No. Will there be safer more effective products available in the future?…I am optimistic that the answer is Yes. Until then, use the chemical that is right for you, and use the correct procedures and equipment to ensure safe, compliant spot cleaning.