The cleaning of cleanroom apparel and related accessories should consist of a reasonably controlled process capable of causing the release of particulate, fiber, and other contaminants without causing degradation to the apparel system. See IEST-RP-CC003.4: Garment System Considerations in Cleanrooms and Other Controlled Environments.
A cleanroom-garment processor should understand the customer’s contamination control and quality needs in order to determine whether and how they can meet the customer’s requirements. The customer should define:
• The type of soil that could appear on a garment. Material safety data sheets (MSDS) sheets should be supplied.
• The latitude the garment processor has in repairing garments, such as patching, etc.
• The acceptable amount of indelible staining.
• A definition of damage that necessitates replacement of garments.
To prepare for laundry service pickup, garments should be placed in covered, lined containers or 100% polyester laundry bags to prevent further contamination. Soiled garments may be mixed in containers; however, boots and overshoes should not be mixed with frocks, coveralls, hoods, or facemasks.
If the user finds an unserviceable garment, it should be put aside and marked with a laundry service warning tag. It should then be bagged or physically separated from the rest of the soiled garments and given to the laundry service representative.
Understanding how cleanroom garments should be handled and maintained is extremely important and should be part of the organization’s quality culture. The user should:
• Keep garments from becoming overloaded with soil, particulate, and fiber.
• Prevent garments from becoming punctured, torn, or excessively worn.
• Store garments between wearings in a controlled environment.
• Adhere to proper donning and doffing procedures to avoid soil loading and physical damage.
• Maintain a sufficient number of changes in the inventory so as not to accelerate degradation of garments because of too frequent use and processing.
The soil sort process, which takes into consideration the customers’ quality requirements, uses both visual and tactile inspection steps to uncover damage before the garment is released for cleaning. For coveralls, typical areas that might show wear include the abdominal area, forearms, elbows, crotch, and zippers. The initial step is to segregate the account by product—coveralls, hoods, boots, etc.
Once segregated, each garment identification marking should be reviewed to ensure that the garment is with the correct account batch. Additionally, if the garment identification marking is not legible, a new marking should be produced and affixed. If a bar code system is used, the soiled garments are scanned into the system.
The garments should be divided into appropriate categories—coveralls, frocks, two-piece suits, boots, shoe covers, hoods, facemasks, etc.
The product after soil sorting may be classified in one of the following categories:
• Serviceable product: needs processing (cleaning).
• Beyond repair product: needs replacement.
• Product requiring repair: repair and processing (cleaning).
• Product requiring special processing: stain removal with subsequent processing (cleaning).
• Unserviceable customer owned product: return to customer for disposition.
Repair of garments
The user and processor should agree upon all repairs; standard operating procedures should specify all facets of the repairs including methods and degree of repairs.
All repairs should be made outside the cleanroom in a manner that will eliminate frayed edges and puckered areas, and should be completed prior to final processing. A limit should be placed on the number of repairs, total area of a repair, and frequency of the repairs to a single garment.
All processing of garments such as laundering (water) and dry cleaning—including testing, inspecting, folding, and initial packaging—should be performed in a cleanroom with a cleanliness class that is equal to or better than the cleanroom environment in which the garment systems are intended for use.
The choice of appropriate cleaning process will depend on the needs of the user, and should be agreed upon by user and processor.
Garments are typically loaded into pass-through washers. The volume of product loaded into the machine should be controlled by either weight or number of pieces. Piece weight should be known since different fabrics and piece configurations may vary in weight. Machines are normally loaded to no more than 80% of rated machine capacity to obtain maximum cleaning efficacy, unless smaller loads, special treatment, or equipment dictates differently.
A normal wash cycle will consist of one or more suds baths followed by a predetermined number of rinses. Water used during the suds bath may be softened and filtered to at least 2.0 µm. Water used during rinses may be softened city water (filtered to at least 0.2 µm), deionized (DI), or treated by reverse osmosis (RO). To minimize microbial growth, in-line ultraviolet sterilization should be built into the water system. If DI water is used, resistivity should be in the 15 to 18 meg-ohm range.
The wash chemical used in the suds bath should be a non-ionic surfactant. The volume of chemical is determined by the product type and machine capabilities. All chemicals used should be filtered to 5 µm.
The garments are unloaded from the washer into the cleanroom environment and loaded into tumble or tunnel dryers. The dryers should be dedicated to cleanroom garments only. All incoming dryer air should pass through HEPA filters. The dryer should be located such that the product can be loaded and unloaded within the cleanroom environment.
The product should be tumbled or tunnel dried at a moderate temperature (typically no more than 140 F) and gradually cooled down at the end of the cycle. Actual temperatures and cycle times are determined by product type and machine characteristics. Care should be taken to prevent the overloading of dryers, as this can cause garments at the end of the dry cycle to be damp and not cleaned.
Garments should be removed from the dryers in a cleanroom environment and folded so that identification labels are exposed and readable once packaged. Special folding requirements should be discussed between the processor and user.
The processor should monitor the number of times that each garment has been processed over its life cycle.
The launder or processor should:
• Avoid the use of harsh chemicals and high temperatures during washing.
• Avoid high temperatures during drying.
• Separate heavily soiled garments from lightly soiled ones during processing to avoid cross contamination.
• Implement acceptable garment-repair standards and procedures that include realistic guidelines for knowing when to replace a garment instead of repairing it.
Packaging and garment shipment
The packaging process and related materials should not contaminate the garments. Packing materials should be free of additives that may release particulate, fiber, extraneous material, or contaminants; adversely affect product cleanliness; or cause odor. Base compounds such as polymers should be certified to ensure cleanliness criteria.
Each garment or garment set should be packaged individually. Packaging material should meet qualification criteria based on nonvolatile residues, total particle levels, and mechanical strength, as well as cleanliness levels per IEST-STD-CC1246D: Product Cleanliness Levels and Contamination Control Program. Over-bagging or placement in a suitable container will minimize the possibility of tearing, puncturing, or otherwise damaging the bags prior to delivery. Excess air, poor seal integrity, and foreign objects should be controlled to prevent contamination.
If a bar code system is used, the garments are scanned out and separated by size, color, and type, according to specifications.
Packaged cleanroom garments should be packed in protective, puncture-resistant, lined containers, or large polyester laundry bags for shipment. Containers should be lined with a clean polyethylene liner and sealed after packing. Containers should be able to withstand normal handling, including gamma irradiation, as appropriate, and should protect garments from damage during transit.
Shipping containers should be clearly and legibly labeled with—at a minimum—the name and department, shipping address, and contents.
Charles Berndt offers consulting services in contamination control, cleanrooms, and cleanroom garmenting, with a specialty in sterile environments. He is a past president and fellow of the Institute of Environmental Sciences and Technology (IEST). Contact: firstname.lastname@example.org
This article appeared in the September 2012 issue of Controlled Environments.