The Bottom Line: Floor Squeegees and Linatex 1. Executive Summary This document explains the importance of floor squeegees on floor scrubbing machines, compares the materials used in making them, describes their characteristics, and shows the relationship between material properties and total cost of ownership. 2. Introduction Commercial and industrial floor scrubbers range from compact, battery-powered models to full-sized, ride-on machines. Made and used around the world, they all operate on similar principles. Each applies a surfactant and medium, usually detergent and water, to the floor. It uses brushes or abrasive pads to loosen dirt and debris while skirts contain the solution to the working width of the machine, then removes the suspended soils and liquids with a vacuum. The last and most critical part in this system is the squeegee; it determines how much is removed from the floor—and how much is left behind. 3. Purpose and Scope To make informed choices, buyers must have basic knowledge about the product class. Useful information about floor squeegees, however, is hard to find. An online search for comparison of squeegee materials yields only price lists. A leading maker of manual squeegees guards its formulation “with the same secrecy and security afforded soft drink formulas.” And even though the international cleaning industry association website www.issa.com offers scores of articles on floor care, not one of them focuses on the selection, use, or care of squeegees. This document is an attempt to provide accurate descriptions and comparisons of floor squeegee materials, supported by industry experience and documented testing. 4. Approach Midwest Rubber Service & Supply Company globally manufactures, fabricates, and distributes high quality rubber products—including floor squeegee blades and skirts. The company offers original and replacement parts, product development support, and material testing for leading manufacturers of floor cleaning machines. The Midwest Rubber testing facility near Shanghai helps researchers measure and compare physical characteristics under controlled conditions for accurate and relevant results. For this document, researchers evaluated multiple properties, such as resilience, modulus, deflection, tear resistance, and wet abrasion, then related those properties to performance in floor squeegees.
Disclaimer: As the patent holder for PRIMOthane®, an oil and chemical resistant polyurethane, and as the exclusive global distributor for floor care squeegees made from Linatex®, Midwest Rubber clearly has a commercial interest in the sale of those products. And because Linatex and PRIMOthane are specifically made to provide effective floor cleaning results, they do well in side-by-side comparisons with generic commodity rubber products. This document reflects test results that assess each material equally. 5. Discussion Clean floors help make public and private shared spaces brighter, safer, and more appealing. Cleaner floors improve occupant satisfaction, employee morale, guest safety, and risk management. This creates a large global market for floor scrubbing machines. With flexible power sources, innovative surfactants, and ergonomic controls, these complex and capable machines clean large areas quickly. Every night, they scrub countless square kilometers of retail stores, schools, hospitals, offices, airports, and other buildings with heavy foot traffic. By keeping floors free of visible grime and unseen slipand-fall hazards, they help promote an image and fact of cleanliness and safety. Manufacturers base their marketing claims on effectiveness and efficiency, emphasizing proprietary features that set machines and makers apart from those of competitors. Yet all the technology that loosens dirt and debris has little value if the squeegee fails to pick everything up. A poorly made, incorrectly chosen, or badly worn squeegee can cancel out the most successful scrubbing job. A squeegee blade that fails to seal against the floor surface will leave behind water, soap, soils, oils, and more.
Safety and Health Clean floors help create pleasant indoor environments. People are happier and more productive when their facilities are clean. They are also safer and healthier: “The services, wholesales and retail trade industries together accounted for the greatest proportion of injuries (over 60%) that resulted from same level falls (over 60%), while the manufacturing sector alone accounted for 16% of injuries that resulted from same level falls.”—OSHA / ISSA Alliance Website: 2007 Liberty Mutual Workplace Safety Index “One of the greatest workers compensation and liability exposures confronting many companies across the country is slip and fall incidents. A fall can result in the loss of a valued employee or the filing of a third-party lawsuit. Many of these incidents can be prevented.”—Loss Prevention Bulletin, Zurich North America According to the National Floor Safety Institute, slip-and-fall accidents cost billions of dollars each year in medical expenses, insurance payments and lost productivity. “Surfaces are only considered hygienically clean when they have been wiped with a cloth. Microorganisms can only be removed by being wiped away. This principle also applies for the cleaning of floor coverings. Through correct cleaning alone, germs can be reduced by up to 80 percent.”—European Cleaning Journal
Natural and Synthetic Rubber Rubber can be made from natural or synthetic raw materials. The most common types are natural latex, harvested from the rubber tree Hevea braziliensis, and man-made chemical polyisoprene, most often created from butadiene and styrene gases. These are blended with other ingredients to create a specified set of characteristics, then extruded, pressed, or molded in sheets, bars, and other shapes. Rubber and polyurethane are thermoset products, with chemical bonds that cannot be reversed. Once the material is heated and formed, it will not change shape again. Even if it is heated to a melting point, it will not have the same properties after it cools. For common industry terms about rubber, please refer to ASTM Standard D1566.
Physical Properties A. Resilience In rubber, resilience can be defined as the ratio of return to impressed energy. In practical terms, resiliency allows rubber to absorb impact from hard objects, then return the energy to the object and regain its original shape. By contrast, rigid materials do not deform; the same kinetic energy that is absorbed by a resilient material would create friction and noise in a rigid one. This property makes rubber a preferable choice of material in many abrasive environments. See Figure 1 below.
Figure 1. Resilience
B. Modulus How easily a material can be deformed by weight or mechanical force is its measure of modulus. The higher the modulus, the more energy is needed to create deflection—a term that describes the relationship of a squeegee blade to a floor surface. A modulus that is too high will result in excessive deflection, which creates noise, vibration, and streaks of water where the rubber did not seal to the floor. Lower-modulus materials require less downforce to create an effective seal with the floor, which reduces machine effort and reduces squeegee blade wear. This critical factor in performance is difficult or impossible to judge without test equipment. As Figure 2 below shows, a comparison of eight squeegee materials revealed significant differences. All the materials looked and felt about the same, but their modulus characteristics varied significantly.
Figure 2. Modulus C. Tear Resistance The purpose of a floor squeegee is to create a seal with the floor surface, so that the vacuum system can recover water and suspended soil from the floor. Any tearing will break that seal and keep the squeegee from doing an effective job. As Figure 3 below shows, this property does not correspond directly to modulus. Some materials are relatively easy to deform but resist tearing.
Figure 3. Tear Resistance D. Wet Abrasion Not all rubber has the same characteristics; each type of rubber wears at a different rate, and responds differently under dry and wet use. Rubber used in a floor squeegee endures wear from both abrasion and wet conditions. As with a squeegee that has incorrect deflection or tearing, one with excessive wear requires immediate adjustment and eventual replacement. This means diminished machine performance, and higher costs for both labor and materials. Figure 4 below shows the wear resistance of several materials.
Figure 4. Wet Abrasion
About Linatex A. Brief History The Linatex product, brand, and company were established in the 1920s. In Processing of Natural Rubber, John Cecil and Peter Mitchell describe how the venture began: In 1923, Bernard Wilkinson discovered a way to ‘cold-vulcanize’ rubber in the liquid phase by adding vulcanizing chemicals to field latex. His objective was to retain as much as possible of the original quality of the latex, by minimizing the extent to which the polymer was damaged by mechanical shear. As this was the first time that vulcanizing chemicals had been added to field latex, he was able to obtain a patent. B. Formulation By vulcanizing field latex, Wilkinson was able to maintain higher integrity in the long molecular chains of the natural polymer, resulting in a higher molecular weight. As latex is subjected to mechanical shearing in handling and manufacturing, molecular chains are disrupted, molecular weight declines, and important physical properties are diminished. Figure 5 below shows how closely Linatex matches the original qualities of latex.
Figure 5. Molecular Weight Distribution C. Applications Its resistance to abrasion, impact, and corrosion has made Linatex a popular choice for protective lining in pumps, valves, chutes, and containers. It was used to line the fuel tanks of Spitfire fighter planes in World War II, re-sealing bullet holes and reducing the risk of fire. According to Weir Minerals, which holds the global patent on Linatex, about 75 percent of the product made today is used in the mining industry.
While other materials have some of the desired properties for use in floor squeegees, Linatex meets more of those criteria than any other rubber. Its characteristics are difficult to reproduce with other materials. As a specialist at Linatex put it, “There are a number of materials in the market that match some aspects but none that match all of them.” Linatex v. Linatex The name Linatex refers to the company, a part of Weir Minerals, and to more than one grade of its products. The material used in mining applications is very similar to the one used in floor squeegees. In testing, however, we found significant differences. Floor care–grade Linatex is made to tighter tolerances for thickness, features a smooth finish on both sides, and delivers measurably better performance when used in floor squeegees. Using mining-grade Linatex for squeegees is both ineffective and cost-prohibitive. D. Economic Concerns Linatex contains 95 percent natural latex, so its cost reflects the market price for rubber. For decades until 2005, the commodity price for rubber remained below US$1 per pound; by the middle of 2011, the price reached nearly US$3. This has made Linatex more expensive to produce. In economic terms, the market for Linatex is inelastic, while the market for squeegee rubber as a product class is highly elastic. Customers who see Linatex as a unique material with valuable characteristics have been willing to pay more for it. Those who view rubber as a generic commodity are more likely to use competing products. E. Price, Cost, and Value Floor squeegees made with inexpensive rubber have less natural latex than Linatex, which means they have fewer of the physical properties that provide higher performance in use. They contain fillers, from carbon black to silica to clay to chalk, that increase hardness and tensile strength but reduce flexibility. Floor squeegees made with lower-quality rubber are sold at lower prices than those made from Linatex. They also deliver lower performance, require more frequent adjustment, and wear out much sooner. Despite its higher initial price, the total cost of ownership over time makes Linatex a more economical choice for many customers. Environmental Advantages According to the International Rubber Research and Development Board, a natural rubber plantation can sequester up to 30 tonnes of CO2 per hectare per year—and natural rubber is a renewal resource with infinite potential.
F. Competing Products Between patent protection and material costs, no other manufacturer can make quite the same thing as Linatex. Because they can match hardness and color, though, some make look-alike products. But the pigment of a rubber has no bearing on its function, and hardness is only one measure of likely performance. Hardness is easy to check, and color is always apparent; these two factors are enough to satisfy some customers that they are buying an equivalent product to Linatex. The less customers know, the more effective this practice becomes. Unprincipled distributors even sell generic rubber under the Linatex name. The simplest way to tell whether a floor squeegee is made of Linatex is to identify the source. Midwest Rubber Service and Supply is the exclusive distributor of floor care–grade Linatex worldwide. Another method is less conclusive but more entertaining. Cut one or more slits in the edge of a floor squeegee and try to tear it the rest of the way. Generic red rubber is relatively easy to tear, while only the strongest and most determined people can get through a piece of Linatex. Figure 6 below shows results from a recent trade event. Two generic products appear in the left and center; the bin containing Linatex is on the right.
Figure 6. Tear Resistance Comparison 6. Conclusion A floor squeegee represents a small fraction of the cost in any floor scrubber. It even costs less than other consumables, such as soap or brush heads. But it makes all the difference in how a floor looks and feels after the machine is put away. The machine’s performance ultimately depends on the squeegee, just as a racing car depends on its tires. For physical characteristics, performance, and total cost of ownership, floor care–grade Linatex provides the greatest value available in floor squeegees.