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Interdisciplinary expertise is best
Modern clothing for the workplace has to satisfy a wide range of different requirements. It must be ideally suited to specific working conditions, promote a sense of identification with the company and be accepted unreservedly by the wearers. This applies particularly to textiles for personal protection equipment (PPE), because this can only do its job if it is worn correctly.
Quite apart from its special functional properties, high-quality protective clothing must be comfortable to wear and fit well. It must also be kind to the skin and, even after long periods of use and repeated cleaning in commercial laundry conditions, still comply with the requirements and safety regulations for its particular purpose.
Incorporating this diverse range of different product features demands interdisciplinary expertise and many years of experience. The Hohenstein Institutes Research Centre in Bönnigheim, in Swabia, Germany, has been working for over fifty years on finding innovative solutions for the whole textile production chain and sees its role as a full-service provider in the fields of application-based research, testing and certification.
The Hohenstein scientists bring together core competencies in the specialist areas of clothing manufacture, clothing physiology, materials testing, textile care, textile finishing and textile hygiene, in a way that is unique in the world. Among the quality tests for textiles are the Öko-Tex Standard 100 and the UV Standard 801. The Hohenstein Research Institute is also notified as a European Test and Certification Centre for Personal Protection Equipment in accordance with EU Directive 89/686 (Notified Body 0555).
Personal Protection Equipment (PPE)
As part of their wide range of services for textile and material manufacturers, garment manufacturers, retailers and importers, the Hohenstein Institutes have, for more than thirty years, also been testing and developing textiles that are to be used for personal protection clothing and clothing components that are classified as personal protection equipment (PPE).
Personal protection clothing protects the wearer from risks at work where these risks cannot be averted by other means. Personal protection equipment can only be marketed if it complies with the health and safety regulations in Appendix II of EU Directive 89/686/EEC. The criteria which the PPE must meet include the following:
- It must offer adequate protection against the risks which it is hoped to prevent, without itself becoming a risk
- It must be suitable for conditions in the workplace
- It must take account of ergonomic requirements and health and safety expectations of the employee, and fit the wearer well ? It is also essential for personal protection clothing to bear the EU mark of conformity (CE) and any other markings such as manufacturer information, type designator, retail name, size, number of relevant European standard, care instructions and pictograms to indicate areas of use.
Depending on the potential risks from which it is intended to offer protection, personal protection clothing is divided into three categories:
- Category 1: simple PPE (e.g. weatherproof clothing)
- Category 2: other PPE, which falls into neither the first nor the third categories (e.g. warning clothing)
- Category 3: complex PPE to protect from irreversible injury and fatal accidents (e.g. protective clothing for firefighters)
All three categories of personal protection equipment require an EU declaration of conformity from the manufacturer or their agent, in accordance with Appendix II of EU Directive 89/686. PPE in Categories 2 and 3 is also subject to EU typespecific approval. For complex PPE in Category 3, a quality assurance procedure in compliance with Article 11 of the EU Directive also has to be followed, i.e. regular product monitoring at yearly intervals.
The regulations in EU Directive 89/686/EEC have been converted into harmonised European norms. For notified centres such as the Hohenstein Research Institute, these form the basis for their work in testing and certification. The normscontrol aspects such as the area of application for protective clothing, safety-relevant properties of the material (e.g. colour, luminance in warning clothing), or the design specifications and performance of the textiles. However, certification as PPE is always given exclusively on the basis of Directive 89/686/EEC. That is to say, manufacturers of protective clothing may deviate from the norms, so long as they can prove that their products comply with the requirements of the Directive in ways other than those quoted in the norm.
One advantage offered by the Hohenstein experts that has been valued for years by many well-known manufacturers is the opportunity not only to test the finished protective clothing but also to test all the primary products when they have been processed.
Another service, in addition to purely testing and certificating personal protection equipment, is the development of innovative protective clothing for company-specific purposes. This entails working closely with the relevant companies to find solutions for working areas where the risks are not catered for by conventional protective clothing, or not adequately. Companies are expertly supported and individually advised, from obtaining the basic information by carrying out demand analysis or market studies, and making a specific plan (performance, sizes, fit, processing requirements, design proposals, compiling technical conditions for suppliers, textile care) through to the practicalities of implementation (acceptance studies, quality assurance).
The starting point for development, and the essential prerequisite when buying protective clothing, is for a risk assessment to be carried out. The next step is then to produce a requirements and performance profile for the PPE, with the risk-relevant criteria being taken mainly from the EU Directive 89/686/EEC and the required properties from the harmonised norms. When producing innovative textiles in practice, reasonable compromises have to be found between the ideal design specification for the planned protective clothing and the materials technology that is actually available, combined with economic costing. What is important is that the last stage in the development of new PPE is always an acceptance study, because if the clothing is not worn it cannot provide protection from the hazards in the workplace.
This is how textile products are produced which are used in complex working conditions and provide protection from a combination of hazards. One example would be flame-resistant clothing which offers excellent warning and weatherproofing properties, while another is the proper cleaning method for this type of special PPE.
Protective clothing with excellent comfort characteristics
Protective clothing that is comfortable to wear plays an important part in ensuring that the wearer feels physically at ease doing his job and is motivated to perform well. If physiological comfort is overlooked, it not only makes for a low level of acceptance by the employees, but physical and mental performance also suffer. This is a factor that is all the more important the greater the risks to which the wearer of protective clothing is exposed in the workplace.
Many different aspects are involved in defining physiological comfort, but it is no longer correct to assume that this is a subjective criterion. Comfort characteristics can be measured objectively.
In their clothing physiological research, the scientists at the Hohenstein Institutes have been working for years on developing objective methods of assessment and drawing up guidelines for the design of occupational and protective clothing which support bodily functions as well as possible. They study three aspects of comfort: thermo-physiological comfort, skin sensorial comfort and ergonomic comfort.
It is essential for thermo-physiological comfort that body temperature remains within a range that people find comfortable and that puts little strain on the body. The limits are determined by the physiological processes that go on in the body. Since heat exchange in the human body takes place to about 90% through the skin, clothing, which covers most of the surface of the skin, plays a crucial role in the way the body’s own temperature equalising function works. It is therefore the aim of the Hohenstein scientists and manufacturers of protective clothing to develop garments which ensure that the wearer maintains a reasonable body temperature in the widest possible range of ambient temperatures and degrees of exertion.
The materials which are used are an important factor in effective and rapid heat exchange. This is why the Hohenstein researchers use a Skin Model to investigate the textiles with regard to various parameters which each represent a material property: thermal insulation, water vapour resistance (breathability), water vapour absorbency, buffering capacities against vaporous and liquid sweat impulses, and drying time.
In order to be able to make predictions about the comfort characteristics of the finished garment or range of clothing, the Hohenstein Institutes also have a life-size thermoregulatory model of a man, in the form of the thermal mannequin ‘Charlie’. This simulates heat production in the human body and, in a climatecontrolled room, also imitates certain sequences of movements.
The figures that are worked out from particular measurements can then be extrapolated by the scientists using predictive modelling techniques. This allows them to make reliable predictions about the range of utility for the garment, i.e. information about maximum and minimum ambient temperatures where it could be used.
The skin sensorial comfort of occupational clothing also plays an important role in the acceptance of protective clothing. Clothing that clings to skin which is wet with sweat is perceived as dragging and restrictive when people move about. Textiles to be worn next to the skin should therefore be napped on the side next to the skin and designed so that they do not stick to the surface of the skin. They should also be made so that they can wick large quantities of sweat away to layers that are not in contact with the skin. To meet these requirements the most important thing is the construction of the underlying textile from which a garment is made. Sensorial comfort for the skin can also be quantifiably assessed by special measuring procedures. For example, the extent to which a textile ‘clings’ to skin that is wet with sweat is simulated on apparatus to measure adhesiveness, resulting in a wet cling index. Other pieces of apparatus are used to measure the number of contact points between the textile and the skin, and the sorption index.
Whether the textile is made of natural fibres such as cotton or from synthetic fibres is in fact of secondary importance – what is more important is the construction of the textile, i.e. the yarn structure and the method of weaving or knitting it. Many of the materials used for occupational and protective clothing are mixed fibres, which combine the positive characteristics of both types of fibre.
Ergonomic comfort includes among other things the fit of the clothing. In fitting tests at the Hohenstein Institutes, garments are tried on by models whose measurements match the size given on the label. The fitting tests for protective clothing, as for everyday wear, are based on sizing charts for ladies’ outer clothing and for men’s and boys’ clothes. Experienced clothing specialists assess the garments for length and width, fitness for purpose, ease of movement and functionality, as well as for their appearance. This test is carried out not only on new garments but also after they have been cleaned, washed and dried. Ideally, the fit of a garment, like the condition of the material, seams, etc. should remain unchanged.
In practice it is important to evaluate not only individual garments but also complete outfits, consisting of underwear, outer clothing and outdoor wear such as jackets, in terms of all three comfort factors. Only where there is a combination of the right thermo-physiological, skin sensorial and ergonomic comfort characteristics will the wearer feel good wearing them, resulting in better performance.
Protective clothing that is tested for harmful substances
In view of the many specific risks and health hazards to which the wearer of protective clothing is exposed in his workplace, it is important that the clothing should not only have excellent functional properties but should not itself be a source of any danger to health. This is why, for over eleven years, the label which says ‘Textile confidence – textiles tested for harmful substances according to Öko-Tex Standard 100’ has served as a reliable guide when buying protective clothing. The Hohenstein Research Institute is one of 11 test institutes represented in 26 countries around the world which are authorised to test and certificate textiles for compliance with the specifications of this standardised list of criteria.
An important benefit of the Öko-Tex System is the applicationbased risk assessment of possible harmful substances in textiles. In general the rule is that the more closely a textile is in contact with human skin, the stricter are the human/ecological requirements that have to be met in testing. Because protectiveclothing sometimes comes into direct contact with the skin and is also often worn for long periods, it has to satisfy the criteria for Öko-Tex Product Class II (Textiles in direct contact with the skin). Only for baby articles (Product Class I) do stricter regulations apply.
An additional factor in the all-round safety of Öko-Tex certificated textiles is the principle that a product can only bear the Öko-Tex label if all its components, including non-textile parts such as buttons and zips, have also passed the tests. Trueto- life simulated tests also ensure that all conceivable ways of absorbing the harmful substances (inhaling, swallowing and skin resorption) are taken into account.
The list of tests, which is the same worldwide and currently includes over 100 separate parameters, is updated annually in line with current legislation and the latest scientific findings. It includes not only substances which are banned but also substances which may be harmful to health and parameters to do with preventive measures. Products bearing the Öko-Tex label contain no azo dyestuffs and no carcinogenic or allergy-inducing dyes. Pesticides and chloro-organic dye carriers are also prohibited. Heavy metals which may be released from the textile under the effect of sweat are strictly controlled. Formaldehyde in baby articles must be ‘non-detectable’, while the maximum levels for Product Classes II-IV are well below the legal limit for declaration. All certificated textiles also have to have a pH value that is kind to the skin and good colour fastness.
At the level of textile and clothing manufacturers, the Öko-Tex Standard 100 is contributing to ever improving safety standards, because it improves the exchange of information about possible problem substances and defines consistent delivery standards. The idea that textile products can be tested and certificated at all stages of processing is a definite advantage in terms of greater planning security. Using preliminary products that have already been certificated avoids duplicated testing and cuts costs.
Protective clothing with extra UV protection
An additional benefit of modern protective clothing is reliable protection against harmful UV radiation. Groups such as builders and street cleaners, gardeners, electricians or foresters, who do their work in the open air or who work in particularly sunny parts of the world are exposed to higher levels of natural UV radiations. In other industries such as welding, UV drying (e.g. manufacturing computer chips or flooring) and the manufacture of UV machines (e.g. sun-beds), employees come into contact with dangerous UV radiation from artificial sources.
In view of the global increase in skin cancer cases, the Hohenstein Research Institute, in partnership with the Austrian Textile Research Institute ÖTI and the Swiss Textile Testing Institute Testex, has developed the UV Standard 801. This independent and internationally valid testing and certification system makes it possible to calculate the UV protection factor of textiles objectively. The figures that are calculated are always based on worst-possible scenarios, i.e. assuming maximum UV radiation and the most sensitive skin type. The final protection factor which the customer sees on the label in the garment is based on the lowest measurement taken during performance testing.
Many textile and clothing manufacturers around the world have already taken advantage of the opportunity to have their products certificated by the International Test Association for applied UV protection (in Europe currently seven well-known textile testing institutes in Germany, Austria, Switzerland, Great Britain, Spain, Italy and Portugal). The scientifically based benchmark of UV Standard 801 guarantees the end-user realistic and reliable predictions about the UV protection provided by textiles and clothing of all types.
Proper care of protective clothing/textile hygiene
In order to maintain the functional properties of protective clothing for long periods and to keep them hygienic, textiles must be properly cared for. The Hohenstein Institutes offer advice on this, for example, to the manufacturers of protective clothing, on choosing materials for the planned application, providing special care instructions or carrying out technical wash tests to ensure that the textiles are fit for the purpose and can be used for the long term. The experts at Hohenstein are also involved in writing norms and validating appropriate treatment processes.
One example of such validated treatment processes is the proper washing of textiles and clothing in accordance with the requirements of the RAL quality labels RAL-GZ 992/2 (hospital laundry) and RAL-GZ 992/3 (laundry from food processing factories). Laundries are awarded these marks of quality if they can demonstrate that the process complies with RAL-GZ 992/1 (domestic and catering trade linen). The quality marks are awarded by the Quality Mark Association for the Proper Care of Laundry, an association of about 350 innovative laundries in Germany, Austria and Switzerland. The award is dependent on meeting the RAL quality and hygiene standards which are closely monitored in a system of in-house and external inspections, and supervised by an independent test institute. The Hohenstein Research Institute offers scientific advice and officially supervises the businesses in the association.
In one of their latest projects, the Hohenstein scientists have worked out what requirements proper care for warning clothing must meet in order to preserve the high visibility of the fluorescent orange/red colour. While the requirements for new materials for warning clothing are specified in the PPE Directive and in EN 471, there were previously no minimum requirements for warning clothing that had been cleaned and no information about suitable washing processes.
In an extensive series of tests, it was investigated which colorimetric parameters affect the perception of fluorescent orange/red warning clothing complying with EN 471, when it has been cleaned, and is worn in busy traffic in bad light. It was also worked out for these parameters which were the critical ranges for detection distance and the size of the visible orange/red area.
The results of the tests showed that the requirements defined in EN 471 for luminance and the location of the colour on fluorescent orange/red warning clothes were confirmed by laboratory tests using test models and corresponding field trials. It must therefore be assumed that the luminance factors that are needed after cleaning must be only slightly less than those specified in the norm. The implication for the cleaning of warning clothing is that, if the specified minimum protection is to be guaranteed, cleaning must only be carried out in a validated, quality-assured process. Only this type of cleaning process can guarantee that the protective function is maintained and thereby contribute to the safety of the wearer.
You can find more information about the activities of the Hohenstein Institutes on the Internet at www.hohenstein.de or you can request free publicity material from [email protected]
For more information on Protective Clothing http://www.osedirectory.com/product.php?type=health&product_id=17
Published: 10th Jan 2004 in Health and Safety International
