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The evolution of ergonomic properties
Dr Emilia Irzmańska discusses the protective and ergonomic properties of gloves.
In the last few years, there has been an increase in the range of ergonomic products available – both those intended for general use and those for specialist applications. Good ergonomics has become a highly marketable quality, and demand is on the rise. Ergonomic products are preferred by consumers who value their health and comfort, as such solutions take into account the physical and psychological abilities of the user. At its core, ergonomics is about catering to the end user’s various needs, which include comfortable working conditions1.
Ergonomics play a major role in the field of personal protective equipment (PPE). PPE does not eliminate the risks inherent in the work process, but instead lowers these risks to acceptable levels.
The effectiveness of PPE depends on many factors, including the selection of an appropriate protection type given the risks identified at the workplace. The routine activities performed by the worker, his or her health status and compatibility with other PPE used in the workplace must be taken into consideration. A good fit is also of great importance. The correct size must be selected and ideally the PPE will include size adjustment systems, as well as other options for improving worker comfort2.
Among other options, occupational safety can be enhanced by wearing appropriate protective gloves. Safety and comfort may be ensured at the design stage by applying ergonomic principles based on knowledge of the needs and characteristics of a given group of end users. Hand and arm protection is often designed for the so called average user, based on averaged anthropometric data, but these gloves may not meet the individual needs of a user. In terms of fitting the shape of one’s hand, for example, 7 inch and 8 inch gloves may perfectly fit persons who are 165–175cm tall, but may be inappropriate for much shorter or taller users. Products labelled as ergonomic inform the user that the items are adjusted to his or her individual needs and expectations, but in some situations this may only be accurate for users with certain hand sizes or for certain applications.
The anatomy of the hand is complicated due to the considerable kinematic and dynamic potential of this part of the body. Hand protection should therefore meet particularly stringent requirements. Even relatively small deficiencies in glove design may reduce grip, strength and manual dexterity.
Ergonomic protective gloves should be adjusted to one’s individual requirements, taking into account:
- Physical build such as size and shape of hands and fingers
- Whether the activity to be undertaken involves fine finger dexterity or gross dexterity
- Individual characteristics such as left handedness
- Limitations such as disability
Gloves should ensure protection and minimise the adverse effects of hazardous or dangerous factors such as injury, muscle fatigue and illness. Arm and hand protection should also enhance wellbeing through positive aesthetic sensations, improve attitude and provide user satisfaction.
Many novel technological solutions have been widely introduced to protective gloves, especially in recent years. The 1980s saw the advent of membranes, which at the time were perceived to be a revolutionary invention. The real textile revolution, however, occurred in the 1990s and it is still an ongoing process.
The needs of persons who wish to work safely and comfortably are often met by synthetic, manmade fibres. The new generations of these fibres are very different from those developed previously, with modern synthetic fabrics now safer and more user friendly. The innovations made in the past 20 or so years, such as carbon and aramid fibres, membranes and 3D knitted fabrics were initially reserved for military purposes. Protective gloves are now made with a variety of increasingly advanced materials that simultaneously ensure adequate protection, comfort and are environmentally sustainable. This paper presents examples of materials and solutions used for improving the design of ergonomic protective gloves.
Cut protection
In situations with a risk of exposure to mechanical hazards such as cuts from sharp or rough elements, workers use gloves made of synthetic fibres. These fibres have been adapted from industrial applications to sports and protective products. They are characterised by high tensile strength, cutting and abrasion resistance and ease of care. It should also be stressed that such fibres are both user and environmentally friendly3.
Protection against mechanical hazards also involves modern textile materials such as non woven padding, which provides shock absorption for the dorsal part of the hand. Such solutions are used in the construction industry, masonry and stonemasonry. Materials exhibiting high mechanical strength are also used in ergonomic gloves in the fingertips and the dorsal part of the hand to protect the metacarpal bones. In turn, ribbed cuffs made of technologically enhanced elastomeric fibres are used for better glove fit above the wrist. When considering the fit and length of glove above the wrist, the longer the cuff of the glove, the more of the arm that will be protected.
Some gloves also contain materials made of polyester and polyamide microfibres, which are characterised by high comfort, ease of care and mechanical strength. Microfibres can have different cross sectional shapes, such as the shape of a sliced orange, which provide a soft grip and hydrophobicity to products without additional coating.
During work with knives a worker’s hands are at risk of serious injury from cuts and stabs. Excellent protection against these hazards is provided by metal mesh gloves made with chain mail. They are recommended for workplaces where a knife is moved toward the other hand, putting it at risk of contact with the sharp blade. Such hazards are present in the food, plastic, leather, textiles and paper industries.
Metal mesh gloves are extremely cut resistant due to their structure. The metal links are usually 0.5mm in diameter and are made of either stainless steel wire, or more recently, titanium. The ergonomic properties of metal mesh gloves are much fewer than those of leather or textile gloves as they do not fit the hand very well. With this in mind, special polyurethane glove tighteners have been designed to prevent gloves slipping off.
New generation textiles
The new generation of protective gloves is increasingly made with polyester fibres, which are already successfully used in sportswear. Thanks to fibres with special cross sections that have varying spacing between them, the gloves exhibit high vapour permeability and consequently are able to quickly transfer sweat away from the skin’s surface. They are also good insulators, irrespective of atmospheric conditions and despite prolonged physical activity of the user.
Other materials used in protective gloves include well known thermal insulating textiles, such as fleeces. Thanks to cutting edge spinning technologies, polyester fibres can be textured in various ways in order to obtain a full and warm handle of fabric, while ensuring protection against freezing temperatures. Such gloves do not absorb moisture, as polyester fibres can only hold up to 1% of their weight, and this small amount is then quickly evaporated. Waterproof and vapour permeable membranes are often used in combination with insulating fleece textiles to prevent water, chemical substances and other liquids and microorganisms from penetrating the gloves.
The application of membranes in multilayer products makes it possible to transport the moisture present inside the gloves away, which alleviates the effects of hand sweating. Furthermore, layers combining different high mechanical strength materials ensure additional protection against heat, abrasion and cutting. The membrane enables moisture transport from inside the glove while exhibiting a hydrophobic effect upon contact with water.
Numerous innovations in the field of textiles have been implemented in hand protection. These range from nano and biotechnological solutions, improved fibre properties and functions and new finishing processes, to the incorporation of active elements in textile materials. Some protective gloves are even made of polyester fibres produced from recycled PET (polyethylene terephthalate) bottles.
Other novel solutions use Teflon fibres in gloves to ensure protection from high temperatures and liquid metals, as well as fibres with antibacterial components, such as polyester fibres that incorporate zinc, silver or copper. These components may be implemented in the form of flock printing, using millimetre long fibre particles. The flock obtained by attaching such small fibres to the internal surface of a glove improves its hygienic properties and provides antibacterial protection, as seen in all-rubber gloves for work with chemical substances. Additionally, the glove fingers are embossed to improve grip and safety.
Flocking increases the mechanical strength of gloves and improves user comfort. Additionally, under the flock lining there may be a layer of protective material. Sometimes, several layers made of different materials are used to enhance chemical resistance, mechanical strength and durability, such as in gloves made of neoprene deposited on natural rubber.
The palms of gloves may be textured to impart ergonomic and anti slip properties, facilitating the handling of smooth, small, slippery and wet items. Another solution that can improve glove ergonomics involves multilayer constructions with both flock lining and non slip texturing on the palm. Ergonomic solutions used in protective gloves include textured surfaces or surfaces covered with dots or other small protuberances.
Other materials used in gloves include anti-UV textiles, which effectively filter harmful solar radiation. These fibres and fabrics contain ceramic particles that protect the skin in a way similar to a factor 30 sunscreen. Until recently, textiles with such properties were mostly used in sports, sanitary and medical products. In turn, neoprene rubber, which exhibits excellent thermal insulation due to its porous structure and which was once used only in diving suits, is now used in the production of protective gloves to prevent the permeation of chemical substances such as mineral oils. Solutions used to increase resistance to mineral oils and to improve the grip and handling of oil covered objects include special polymer coatings with microchannels. These drain away chemical substances and ensure good contact between the glove and the surface of the handled object4.
Nanomaterials
The recent development of materials characterised by nanometer sized particles and interesting physical and chemical properties has given rise to many new solutions for arm and hand protection. Nanomaterials are of interest to the scientific community, industry and occupational safety institutions due to their improved, or indeed novel, properties as compared with materials made of traditional micrometer sized components.
The emergence of nanoadditives to polymer composites has created new possibilities for protective products such as chemical resistant gloves. This is based on experience from other fields, which showed that at appropriate levels of nanofiller dispersion the mechanical properties of materials are enhanced, flame and chemical resistance increases and hardness and rigidity become balanced. Efforts are now underway to use nanoparticles in specialised materials to provide a barrier against harmful chemical substances, such as mineral oils5.
In textile engineering, nanotechnology gives the opportunity to increase the functionality of textiles by imbedding them with specific barrier properties to protect them against selected external hazards. The addition of a variety of ceramic nanoparticles, metallic nanopowders and fullerenes, or carbon nanotubes, may lead to increased thermal resistance and reduced flammability, as well as improved strength, sorption, optical, electroconductive and even antibacterial properties.
Nanotechnology also deals with processes of fibre surface modification, which lead to altered micro topography and can affect the chemical nature of the surface, thus influencing the use of items made with this technology.
Textiles produced using nano technology have been applied to give gloves the qualities:
- Dirt, water and oil repellence
- Rapid moisture evaporation
- Water vapour permeability
- Warmth to the touch
- Odour absorption
Transfer of sports protection
Alongside the widespread use of gloves in sports such as martial arts, skiing, cycling and climbing, industrial workers have also started to feel the need for comfort in their protective gloves.
The increasingly intensive progress of materials engineering and improved designs adopted from sports products have given rise to many interesting ergonomic solutions in the production of protective gloves6. The protective gloves currently available on the market exhibit many similarities to the design and production technologies applied in sports gloves.
Let us consider the example of ergonomic protective gloves with good thermal and hydrophobic properties for outdoor work involving mechanical hazards. In terms of design, their sports like features include an ergonomic grip, obtained thanks to special design in the finger and wrist areas, as well as the application of materials with different strength characteristics in the palm. Their construction is adopted from modern mountain climbing gloves and incorporates a membrane component in the internal section to ensure breathability and impermeability, while not affecting manual dexterity. The cuff contains elastomeric fibres running vertically and horizontally and enables good adjustment of the glove to the user’s wrist.
Protective gloves drawing on sports designs are characterised by a more ergonomic construction that can support all hand movements better than a traditional sports glove. The application of an elastic woven or knit fabric between the fingers in the dorsal part of the glove ensures good fit and an ergonomic grip. This can be seen in leather gloves for protection against mechanical factors, which often have seams adapted from cycling gloves. The seams impart an ergonomic profile and enhance glove fit. The placement of seams in the palm area improves manual dexterity during gripping and handling larger elements. As another example, protective welding mittens are characterised by an ergonomic construction thanks to the incorporation of a special anatomical tunnel in the palm area, which ensures a good fit and comfortable grip.
Ergonomic evaluation
Two standard methods currently exist to evaluate the ergonomic properties of gloves7,8. In both cases, the ergonomic properties of protective gloves are evaluated based on subjective sensations concerning fatigue of the upper limb, discomfort and problems with glove fit. The above methods, however, do not include any measures that would allow the ergonomic properties in question to be measured objectively.
According to the literature, the lack of objective evaluation is a very important issue, as gloves with inappropriate ergonomic characteristics may adversely affect task performance time, precision, tactile sensibility, grip strength, dexterity, and range of motion9.
Gloves that are too tight may restrict the motion of the upper limb and blood flow, leading to cramps, hand fatigue and excessive sweating, while gloves that are too loose may decrease dexterity, leading to compensation strain. This could pose a risk to persons working near machines with moving elements or clamps.
Other research has shown that protective glove users reporting discomfort are less disciplined in terms of glove wearing and more prone to upper limb injury. It has also been found that uncomfortable glove materials may reduce blood circulation, cause numbness, limit finger and hand motion, and reduce work performance.
Conclusion
The subject of technology applications in protective gloves is very broad and explanation of all connections between ergonomics and glove construction and materials could easily fill several volumes of scientific literature. The methods of imparting protective and ergonomic properties to gloves change with technological progress. It is difficult to predict what researchers, and in turn manufacturers, are going to incorporate in subsequent generations of protective gloves.
Today, modern gloves offer not only protection, but also an unconventional combination of cutting edge technologies with functionality and comfort. This new generation of protective equipment comes in response to the requirements of contemporary protective glove users. Designers continue experimenting and often surprise us with the quality of their solutions. While the gloves they create are primarily focused on work safety, they also indicate to many manufacturers possible directions that protective equipment may take in the future.
Acknowledgement
This article is based on the Phase III results of the programme Safety and Working Conditions Improvement. The programme is being coordinated by the Central Institute for Labour Protection – National Research Institute. It is funded from 2014 to 2016 in the area of research and development works by the Ministry of Science and Higher Education and The National Centre for Research and Development.
References
1. Koradecka D (ed), 2002. Work Science – Safety, Health, Ergonomics, CIOP, Warsaw. Volumes 2, 8. 2. Koradecka D (ed). Use of Personal Protective Equipment in the Workplace. Handbook of Human Factors and Ergonomics. John Wiley & Sons Press, USA 2012, pp. 895–910. 3. Leitch P, Tassinari TH, 2000. Interactive Textiles: New Materials in the New Millennium. Part 1, Journal of Industrial Textiles. 29 (3), 173-190. 4. Krzemińska S, Irzmańska E, 2013. Preliminary Evaluation of the Ergonomic Properties of Gloves for Protection Against Mineral Oils Based on Manual Dexterity Tests. Journal of Testing and Evaluation. Volume 41, No. 6, pp. 875–882. 5. Krzemińska S, Irzmańska E, 2011. Exposure to mineral oils at worksites and novel solutions for polymer protective materials in selected personal protective equipment. Occupational Medicine. 62(4), 435-443. 6. Velani N, Wilson O, Halkon BJ, Harland AR, 2012. Measuring the risk of sustaining injury in sport a novel approach to aid the re-design of personal protective equipment. Applied Ergonomics. 43(5):883-90. 7. EN 1082-2:2002 Protective Clothing – Gloves and arm guards protecting against cuts and stabs by hand knives – Part 2: Gloves and arm guards made of material other than chain mail. 8. EN 420:2003+A1:2009 Protective Gloves. General Requirements and Test Methods. 9. Dianat I, Haslegrave CM, Stedmon AW, 2012. Methodology for evaluating gloves in relation to the effects on hand performance capabilities: a literature review. Ergonomics. Volume 55, No. 11, 1429-1451
Published: 21st Jul 2014 in Health and Safety International
