Interdisciplinary Expertise

Makes for the best in protective clothing

Protective clothing offers the wearer reliable protection against health risks and environmental effects which cannot be avoided in their line of work. These may include intense heat and flames, cold and wet, all types of mechanical and physical stresses, from cuts to spray from molten metal and sparks through to electricity and electrostatic charges, chemical substances and gases and poor weather and lighting conditions.

Quite apart from its special functional properties, high-quality protective clothing must be comfortable to wear and fit well. Otherwise there is a risk that it will not be accepted by the wearer and therefore not used correctly. 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.

In many instances, protective clothing requires combined material and functional properties in order to fulfil its intended purpose. Clothing for the rescue services must guarantee good visibility in traffic in all lighting and weather conditions, offer protection against mechanical and climatic influ-ences (wet, wind, cold) and be constructed in such a way that, should it become contaminated with pathogenic agents, it can be treated using a validated disinfection process. Rescue jackets in general use nowadays consist of a fluorescent background material with reflectors applied which satisfy the requirements of the warning effect in line with EN 471. The background material also provides protection against flying sparks thanks to an appropriate finish. A second layer of material consisting of a watertight breathable membrane protects the wearer against the wind and weather. A removable thermal lining provides additional protection against cold external temperatures.

Translating such a broad range of requirements into suitable practical products demands interdisciplinary expertise and many years of experience. The Hohenstein Institutes Research Centre in Bönnigheim, 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.

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 type-specific 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 norms control 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.

The harmonised norms, in accordance with which protective clothing is tested, are published in the official journals of the EU states. An overview of all the relevant requirements for personal protective equipment can be found on the Internet at:- http://europa.eu.int/comm/enterprise/newapproach/standardization/harmstds/reflist/ppe.html. Examples of the wide range of harmonised norms relating to protective clothing include:

• EN 471 High-visibility warning clothing
• EN 469 Protective clothing for fire fighters
• EN 531 Protective clothing for industrial workers exposed to heat
• EN 368 Protective clothing – protection against liquid chemicals
• EN 50286 Electrical insulating protective clothing for working on low voltage installations
• EN 381 Protective clothing for users of hand-held chain saws etc.

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 and the more extreme the climatic conditions 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. Here we look at three aspects: thermo-physiological, skin sensorial 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. 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 such as 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 whole range of clothing the Hohenstein Institutes also have a life-size thermoregulatory manikin, “Charlie”. This simulates heat production in the human body and, in a climate-controlled 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.

Skin sensorial comfort 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.

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, i.e. washed, cleaned 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

Currently, 18 test institutes represented in 31 countries and around 6,000 companies worldwide throughout all the stages of the textile processing chain are involved with the Oeko-Tex Standard 100. Over 42,000 certificates have been issued to date for millions of individual products. This has made the Oeko-Tex label a reliable safety benchmark throughout the textile industry and the best-known test mark of its kind. The focus for certification is on clothing, soft furnishings and baby articles, but more and more manufacturers of occupational and protective clothing are using the Oeko-Tex label to show that their products are not harmful to health, and offer the wearer human/ecological security.

An important benefit of the Oeko-Tex System is the application-based 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 protective clothing sometimes comes into direct contact with the skin and is also often worn for long periods, it has to satisfy the criteria for Oeko-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 Oeko-Tex certificated textiles is the principle that a product can only bear the Oeko-Tex label if all its components, including non-textile parts such as buttons and zips, have also passed the tests. True-to-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 Oeko-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.

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. An important advantage of this measuring process is that, unlike other test methods, for example the Australian/New Zealand norm, it also takes account of the condition of the textile product in use, i.e. criteria such as the strain imposed on a fabric by stretching or wetting, or mechanical wear due to wearing and washing.

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.

Thus, 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.

A brand new service offered by the Hohenstein Institutes is the certification of quality-assured cleaning of protective clothing following objective evaluation criteria. In the associated research project, textile experts at Hohenstein had already developed a predictive model which makes it possible to determine how many cleaning cycles personal protective equipment can undergo given specific process conditions while still complying with the required safety specifications (e.g. EN 471 for warning clothing). The new PPE audit can also make protective clothing suitable for use for significantly longer periods and, given the high costs of purchasing PPE, can contribute to more effective cost management for textile rental companies and users.

In order to achieve certification for the cleaning of protective clothing by the independent Hohenstein Research Institute, a test is first required to check whether the PPE product in question is suitable for cleaning in commercial laundry conditions. Secondly the cleaning process must be validated to ensure that the protective function and the cleanliness are adequately retained. If both conditions are met, laundries and textile service providers may label their PPE products with the relevant certificate. Laundries which have already been awarded the RAL 992 Quality Mark for the Proper Care of Laundry in particular will be considered for certification as the washing processes used already comply with the required criteria.

The specifications made as part of the certification process on the maximum number of possible cleaning processes in line with EU directive 89/686/EEC always refer exclusively to the validated product and the related processes in the laundry in question.

Another area of work where textile hygiene is of great importance con-cerns barrier textiles for medical use. Operating theatre textiles such as the patients’ robes, and theatre gowns, caps and masks should protect both the patient and hospital staff from infection. The Hohenstein scientists work firstly on optimising the barrier effect of textiles and researching suitable methods for testing the protective effect of medical textiles. At the same time, however, they are working on developing and validating new cleaning methods so as to improve existing standards of hygiene still further.

Current innovations in protective clothing

Ongoing product innovations are an important factor in ensuring that PPE provides an optimal protective effect. As part of “Solartex”, a joint project with the Institute for Physical Electronics (IPE) at the University of Stuttgart, supported by the Ministry for the Economy using funds from the Landesstiftung Baden-Württemberg, clothing technologists from the Hohenstein Institutes have been looking into the possibility of integrating flexible solar cells into clothing. The solar cells are used for the network-independent energy supply of mobile communications and entertainment electronics or intelligent systems to monitor health which will be used in the clothing of the future.

In this context, scientists from Hohenstein together with the protective clothing manufacturers Tempex and other project partners developed a prototype of an intelligent warning jacket on which light emitting diodes are adapted which are able to release active warning signals in the dark. The energy for this is generated using solar cells incorporated into the shoulder and back sections which is then stored in a rechargeable battery. It is hoped that the high tech clothing product will offer workers such as foresters, railway workers, road workers or airfield workers increased protection compared to conventional warning clothing as it is not dependent on the reflection effect produced by external light sources.

A new service from the Hohenstein Institutes is the “Tested Quality” label, which is designed to support textile and clothing manufacturers in targeted marketing of their products, and serve as a reliable aid for consumers when buying textiles. Quality testing is currently possible in the fields of clothing physiology, UV protection, consumer tests (appliances), product testing (colourfastness, pilling) and textile services (textile leasing).

In clothing physiology, for example, biophysical measuring systems are used to evaluate the following product properties: comfort characteristics, physiological comfort, breathability and sleeping comfort rating. When further test results from other working areas are added to these, reliable and far-reaching quality predictions can be made for a product.

The Hohenstein quality label is essentially suitable for all clothing prod-ucts and soft furnishings. For protective clothing, the information on the CE mark is currently sufficient as an indication of quality. For manufacturers of other professional and workplace clothing, the “Tested Quality” label, with its specific evaluation of comfort, fit or UV protection, offers the ideal way to highlight the quality features of their products.

You can find more information about the activities of the Hohenstein Institutes on the Internet at www.hohenstein.de. 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 2005 in Health and Safety International