The importance of gloves
11/01/2005
By Robert McIlvaine and Betty Tessien, McIlvaine Company
Cleanroom operators around the world will spend close to $1 billion for gloves this year. It is the largest and one of the most critical purchases for cleanroom operators. Because gloves are in constant contact with the user, comfort and tactile sense are of high importance. This can be affected by material selection, sizing, thickness and length. Due to the fact that the gloves are frequently in contact with the product, the cleanliness and protective aspects are also critical.
Glove materials
Natural rubber latex gloves have been the first choice for cleanroom gloves. They are the most elastic and durable, have good acid resistance and come in various thicknesses and lengths. Latex comes in hand-specific, ambidextrous, textured and smooth versions. However, concerns about allergic reactions and a reduction in the cost differential have allowed nitrile to capture a significant share of the market. Latex falls short in static dissipation, and also sheds its outer layer as it becomes worn. As it ages, it continues to decay and flake.
Vinyl (PVC) gloves, invented by Oak Technical LLC in the late 1950s, are in second place. They are not as durable or as good a barrier as latex, however, and because vinyl may outgas, it should be tested for such. Vinyl has several advantages: It is inert and does not shed many particles; no powder is used in making vinyl gloves; it’s non-allergenic and has some antistatic properties; and vinyl is usually a few cents cheaper than latex. Vinyl is also well suited for double gloving or wearing glove liners. The biggest drawbacks of vinyl gloves include: loose fit, low durability, poor acid/base resistance, and touch transfer. Also, fingernails may puncture vinyl gloves. Vinyl is primarily sold in an ambidextrous smooth finish, and is best suited for a dry environment. Some manufacturers take vinyl to contract manufacturers for additional cleaning and packaging.
Nitrile is more durable than both vinyl and latex, but it’s an inelastic polymer, which is more difficult to form into a thin, disposable glove. Nitrile gloves are currently available in the same thicknesses as natural rubber latex and PVC. Newer generations of nitrile gloves are overcoming some of the disadvantages seen in earlier versions. Nitrile has better resistance than latex to a broad range of chemicals, performs well with solvents and is naturally antistatic. It is three times more puncture resistant than latex or vinyl. In extended use, nitrile may provide less hand fatigue because it allows the glove to form to the hand.
Polyurethane gloves are higher in cost but can be very thin and have good chemical and antistatic properties. Other glove materials include neoprene, Hypalon®, Viton®, and butyl. They are not all appropriate for ISO Class 5 (Class 100) cleanroom use but are available for various applications including drybox isolators, which are the cleanest of the cleanrooms. Renco Corporation’s complete line of 18-inch to 32-inch glovebox gloves includes: Hypalon and nitrile for aseptic applications; butyl for gas and moisture permeation control; neoprene and natural rubber for general-purpose applications; and Viton and polyurethane for specialty chemical applications.
Costs
The cost of cleanroom gloves varies widely depending on the material type, thickness, and manufacturing procedure, including washing prior to shipment and/or manufacture in a cleanroom atmosphere. The cost equation is further complicated by the practice of using double gloves and glove liners.
Special cleanroom gloves sell for as much as $15 per pair. ISO Class 5 nitrile gloves with 11 mil thickness, embossed grip and multiple washings prior to shipment sell for $4 per pair. On the other hand, antistatic vinyl cleanroom gloves with 6 mil thickness sell for $0.30 per pair. ISO Class 5 latex gloves-after washing to reduce particulate and remove extractables-are typically $.40 per pair or less.
 Table 1: Average glove prices by cleanroom class |
Average prices per glove have been compiled from vendor data and from an end-user survey (see Table 1). These are prices paid by the ultimate user, and reflect an average of reusable and disposable, and general and special use. We estimate ISO Class 3 and 4 (Class 1 and 10) gloves at $0.50 per pair and ISO Class 5 at $0.40 per pair.
Market
Purchases of gloves for cleanroom applications around the world are predicted by McIlvaine Company to be $953 million in 2005 (see Table 2). The semiconductor industry will be by far the largest purchaser.
 Table 2: Glove purchases by industry ($ millions) |
McIlvaine asked glove suppliers and distributors to comment regarding glove selection, glove pricing, sourcing, consumption and quality.1
Glove selection
Cintas distributes and sells all types of gloves as specified by the customer. Because of the chance of a worker succumbing to a latex allergy and the health and safety concerns for their employees, the majority of Cintas customers specify nitrile gloves instead of latex ones, comments Jan Eudy, director of quality assurance for Cintas. Disposable gloves constructed of nitrile have developed into durable, clean gloves with good dexterity.
The categorization of gloves as Class 1, 10, 100, 1000 or 10,000 is inaccurate terminology. Prior to 1999, cleanrooms were certified to the above classifications per Federal Standard 209E. Since 1999, cleanrooms are certified to equivalent ISO classifications per ISO 14644 standards. Gloves are tested for use in a certified cleanroom according to the test protocols of IEST-RP-CC005.3 published in 2002. These documents are the testing criteria in the U.S. for ISO-certified cleanrooms.
The Asian market has not completely picked up on glove testing procedures-such as enumerating particles using liquid particle counters and testing for bioburden, anions, cations, and various volatile and nonvolatile chemicals that come off the glove. Eudy states, “If glove manufacturers worldwide tested to the current industry standards and practices, the customer would have higher confidence in the quality of their product.”
The semiconductor industry is more concerned with particle contamination, while the pharmaceutical sector’s biggest concerns are biological contamination and bioburden. Each industry, therefore, has different protocols. IEST-RP-CC005.3, Gloves and Finger Cots for Cleanrooms and Other Controlled Environments, provides the information necessary to specify, select, test and implement cleanroom-compatible gloves and finger cots (reusable and disposable) appropriate to the specific ISO-classified cleanroom environment. This recommended practice also describes the cleaning and various applications of gloves and finger cots.
Sebastian Russo of Connecticut Clean Room remarks that when the latex scare and allergy threat came out, nitrile was about the only alternative people had. Many companies switched and have not been inclined to change. However, Connecticut Clean Room still sells latex gloves to some companies that have never had any problems with latex reactions.
A lot of problems come from poorly processed latex gloves. Carmen Castro of MAPA states that if natural rubber gloves are correctly processed, chlorinated and DI washed, there are very few issues. The percent of workers that actually have a natural rubber allergy is very small. Various MAPA glove styles contain natural rubber, including its unique triple polymer cleanroom gloves, which contain natural rubber, nitrile and neoprene. The company specializes in high-end gloves used for chemical protection, as well as heavy-duty gloves. MAPA also offers a longer 24-inch cleanroom glove that offers more arm protection to the worker, and they are developing a line of gloves for gloveboxes. MAPA gloves are manufactured in Malaysia in their own plants, which are monitored very carefully. The industries that buy these gloves like the comfort and protection they provide.
According to Castro, the semiconductor and electronics markets are more strict about approval, particle counts and validation records than the pharmaceutical industry. Once customers are satisfied, they usually remain faithful to their supplier.
MAPA offers a thicker, heavy-duty, acid- and chemical-resistant glove that is popular with semiconductor companies because of its cleanliness and ability to stand up to process chemicals. Because the pharmaceutical industry is concerned with bioburden and biological contamination issues, its main concern is to have a powder-free disposable glove that can be sterilized.
Reusable gloves are usually knit or stitched with dipped or laminated palms; they’re used for specialty needs such as ESD, heat applications or extra grip. They are more likely to be selected if the facility has a laundry available. Wilshire makes a reusable Lycra glove that is collected by the user and sent to a processing center to be cleaned, much like a garment or a knitted polyester glove. Processing is labor intensive and more costly; however, some of the established cleanrooms continue to follow this procedure with specialty gloves.
Glove selection for use in glovebox applications is unique. Rich Renehan of Renco Corporation explains that selecting the proper gloves for isolation chamber applications requires a careful analysis of processes and functionality with respect to user protection, ergonomics, product protection and production objectives. Selection of the proper “user friendly” interface for the end user is as critically important as particle filtration, barrier materials, fixture selection, monitoring pressure, leak testing, entrance and egress, etc. Each of these items needs equal consideration with respect to the process as a whole.
Glove pricing and sourcing
Cleanroom manufacturers face extreme pricing pressures and are constantly challenged by their customers to deliver more cost-effective and efficient solutions. This is true for semiconductor and disk drive manufacturing as well as for biotech and pharmaceutical manufacturing. Wolfe Birkie of Kimberly-Clark confirms that their manufacturing customers demand that they continue to add value by providing comprehensive product-testing information as well as by sharing their manufacturing efficiencies. Customers are not in the glove-testing business, he explains, so they rely on Kimberly-Clark to provide comprehensive, certifiable testing information on their cleanroom products.
Not only are K-C’s products lot-traceable, but customers can easily review Certificates of Analysis for each lot of cleanroom gloves-as well as a twelve-month trend analysis for particles and extractables-through Kimberly-Clark’s Web site. Overall, higher-end cleanroom manufacturing facilities demand performance while price drives the decisions at lower-end assembly houses.
With the exception of Oak Technical LLC-the only glove manufacturer in the U.S. according to Bill Soellner, Oak’s director of sales and marketing-most gloves come from Malaysia, although China is emerging into the market as a supplier and buyer as well. According to Renco’s Renehan, Korea and Taiwan are noted for producing PVC gloves, while Thailand and Indonesia are best known for natural rubber latex and nitrile gloves.
Consumption
For pharmaceutical ISO Class 5 environments or better, regulated by FDA cGMPs, it is required that a new pair of gloves be donned-as well as a second pair of gloves over the donned gloves-upon each entry into the clean space. If a glove malfunctions or develops a pinhole, obviously it must be changed immediately. On average, cleanroom employees in the pharmaceutical industry change gloves approximately four times per shift. Some pharmaceutical companies require workers-when handling gel caps, for instance-to change gloves once an hour if they are concerned about bioburden or biofilm build-up. According to Soellner, pharmaceutical companies opt for gloves that can be sterilized before use.
Although the semiconductor industry is not a GMP-regulated industry, similar procedures are followed because changing gloves frequently, wearing donning gloves, and using double-glove techniques improve yields.
Quality
Most cleanroom gloves are manufactured in ISO Class 5 or 6 cleanrooms and cleaned to be suitable for use in ISO Class 3 cleanrooms. Because a large percentage of gloves come from Asia, they must be critically reviewed for quality parameters because they may not be manufactured in a cleanroom or tested with current, appropriate testing procedures. They may be advertised to be cleaner than they actually are. Because of the potential for quality issues, which can impact both users and product yields, glove quality and manufacturing facilities must be monitored for quality assurance.
Accurate sizing was an issue for a time because of the larger hands of Americans: Molds for the gloves were not meeting the needs of the buyers. That issue seems to have been resolved but could become a problem again as the Chinese market grows, states Russo. ASTM has dictated standards for glove dimensions, which typically have an allowance of +/- 10 mm on the palm width. Manufacturers looking to cut cost may produce on the lower end of the spectrum, as this will use less material.
Nitrile appears to be the direction of the market. It has become the choice for many cleanroom applications because of its durability, chemical protection, low particles, low extractables, fit, and ESD properties. Although natural rubber latex and vinyl are less expensive than nitrile, the differential has decreased and, as such, the acceptance of nitrile has risen.
Vinyl gloves seem to have less dexterity and a loose fit, creating less comfort and confidence. However, Soellner states that although PVC has a looser fit than comparable latex or nitrile gloves, some users prefer that because it is perceptively cooler to the skin and the PVC transmits the ambient temperature much better than other barrier materials. One characteristic of Oak PVC gloves is that the fingertips cling to the skin, which gives the gloves exceptional tactile dexterity while still offering a loose fit. Much of the comfort factor in any glove is influenced by user preference and perception, along with the users’ habits for their specific applications.
References
- The following individuals provided industry and product information: Jan Eudy, Cintas Corporation; Carmen Castro, MAPA; Sebastian Russo, Connecticut Clean Room; Bill Soellner, Oak Technical LLC; Wolfe Birkie, Kimberly-Clark Safety & Industrial; Rich Renehan, Renco Corporation; Tony Shouga, KNF Clean Room Products.
Robert McIlvaine is president and founder of the McIlvaine Company, Northfield, Ill. The company first published “Cleanrooms: World Markets” in 1984 and has since continued to publish market and technical information for the cleanroom industry.
Betty Tessien is the cleanroom publications editor for the McIlvaine Company.