RESEARCH & INNOVATION. Clothing physiological research in the service of wear comfort

RESEARCH & INNOVATION Clothing physiological research in the service of wear comfort

Preface Prof. Dr. Stefan Mecheels Head of the Hohenstein Institute Man has always been interested in the relationship between clothing and physical well-being. The scientific discipline of clothing physiology, on the other hand, which has been and continues to be shaped primarily by the Hohenstein Institute in Germany since 1946, is comparatively young. In this special publication, we have summarized the milestones of a development that ranges from the first form of human clothing made from hide and leather through to modern functional textiles. Using the research methods of clothing physiology, items of clothing, as well as bedding and sleeping bags can now be optimally tailored to their respective area of application. The innovative strengths of the scientists at Hohenstein formed the foundation for this. Clothing physiological research owes its pioneering and now internationally recognized test systems such as the Hohenstein Skin Model and the articulated thermal manikin, Charlie, to their work. On 1 October 2009, the Hohenstein Institute have bundled its professional competencies in the current company segments Clothing Physiology and Textile Services & Innovations into a new department by the name of Function and Care. The department will be managed by Dr. Andreas Schmidt who will be succeeding Prof. Dr. Karl-Heinz Umbach, who has retired from the operational business after 33 years of occupation for the Hohenstein Institute. With pride, we look back on 60 years of work in the service of wear comfort and look forward to continuing to be actively involved in creating future generations of innovative textiles. PUBLISHER: Hohenstein Group Schlosssteige 1 74357 Boennigheim GERMANY Tel.: +49 7143 271 0 Fax: +49 7143 271 94199 E-Mail: info@hohenstein.de Website: www.hohenstein.de CONTACT: Dr. Timo Hammer CEO Tel.: +49 7143 271 410 E-mail: t.hammer@hohenstein.de HOHENSTEIN Prof. Dr. Stefan Mecheels Head of the Hohenstein Institute 2017 Hohenstein Institute 2 3

TOPICS Clothing physiological research at the Hohenstein Institute in the service of wear comfort Clothing for the naked ape 6 Clothing and mysticism 7 The birth of qualitative clothing physiology 8 The dawn of a new age in the textile industry 8 Expertise made in Hohenstein 9 The birth of quantitative clothing physiology 11 The measure of all things 12 The overwhelming success of synthetic fibres 13 Ever since its foundation in 1946, one of the main focuses of research at the international textile research and service centre at the Hohenstein Institute in Bönnigheim has been the interaction between textiles and human physiology. The objective was and remains the development of clothing, bedding and vehicle seats which optimally support temperature regulation depending on the environmental climate and activity, in other words, offer a high level of comfort. As the feel of the textiles against the skin, i.e. the skin sensory properties, and the fit (ergonomic wear comfort) are crucial factors in determining whether a textile product is perceived to be pleasant, these factors must also be taken into consideration at the product development stage. The founder of the institute, Prof. Dr.-Ing. Otto Mecheels, his son and successor as head of the institute, Prof. Dr. Jürgen Mecheels, together with the present deputy head of the Hohenstein Institute for Clothing Physiology, Prof. Dr. Karl- Heinz Umbach, are regarded as the fathers of research into clothing physiology in Germany, and thus as pioneers for functional textiles in their current form. Thanks to the Skin Model and Charlie, the articulated thermal manikin (figure 1), and special skin-sensory equipment developed by the Hohenstein specialists, the discipline of clothing physiology now has a range of clothing-specific parameters which enable wear comfort to be evaluated objectively. This made it possible for Wear comfort is ess-sense-tial 14 High marks for comfort 15 As you make your bed... 16 Figure 1: Using Charlie, the human thermoregulation model, the wear comfort of clothing can now be objectively assessed and optimised. Freezing in a sleeping bag? 17 Comfort mobilises 18 Children are more than just small humans 19 The battle against cold hands and perspiring feet 20 Clothing physiological measurement methods at a glance 21 4 5

Figure 3: The thermophysiological and skin-sensory properties of clothing, such as that worn by the iceman, Oetzi, in the Neolithic period, can also be determined using clothing physiological methods. Figure 4: Drawings in Egyptian tombs show the special importance attributed to cult garments made of linen. Figure 2: Up until modern times, humans only protected themselves against the effects of weather with clothing made from natural materials such as wool, leather and hide. the first time in the long history of clothing to evaluate and optimise wear comfort specifically in relation to defined areas of application and requirements. Previously, the choice of materials and patterns was influenced to a large extent by mystical beliefs that were closely linked to cultural development. Clothing for the naked ape Loss of body hair represents a milestone in human evolutionary history. Like all mammals, the first primates regulated their body temperature through respiration, which significantly restricts the amount of heat dissipation. Early man used his entire body to dissipate heat, however, and was therefore superior to the majority of animals in terms of endurance and adaptability. Moreover, it was only when he had acquired the ability to sweat that the naked ape gained the ability to communicate using language even when it was extremely hot or during strenuous exertion. The ability to sweat is only really effective however if there is no body hair to restrict the circulation of air. During the course of evolution, man therefore lost the majority of his body hair. The colonisation of colder areas of the world was consequently only possible for early man with the invention of protective clothing (figure 2). But even under climatic conditions that do not require the body to be protected by clothing, typical forms of clothing developed as part of man s cultural development on ethical-religious grounds (figure 3). Clothing and mysticism The use of natural materials such as hide, wool, cotton and linen have always had mystical, as well as practical associations. In Egyptian civilization, linen fabrics, for example, were regarded as particularly pure, and were therefore the preferred choice for cult purposes (figure 4). Sheep s wool, on the other hand, was regarded as impure and only used for clothing for the lower levels of society. Similarly, woollen clothing could not be used for burial in order not to jeopardise the passage to the realm of the dead. The first reflections on the function of clothing were made by the Greek philosopher Empedocles around 500 B.C. He put forward the theory that the skin breathes. Clothing should not prevent the perspiration that occurs as a result of cutaneous respiration, and should also help to avoid toxins penetrating from the environment. Linen fabrics were said to best fulfil these requirements. The concept of cutaneous respiration and the resulting rejection of woollen and cotton clothing by the higher social classes continued until the baroque period. Nobility and the upper clergy dressed in linen and silk. A paradigm shift occurred around 1650: Santorius, a physician from Padua, put forward the theory that serious diseases could be avoided by stimulating perspiration from the body by means of particularly warm clothing. Against the background of the devastating plague epidemics, which had depopulated entire areas in Europe since the middle ages, he recommended wearing as many layers of woollen clothing as possible. He ascribed its warming effect to the residual inner warmth of the sheep. Based on the ability of wool to absorb large quantities of moisture, toxic vapours from the surrounding air were also believed to be absorbed by the wool. It was also thought that pores were opened as the wool rubbed against the skin, thus stimulating cutaneous respiration. The extent to which the belief in the superiority of wool over linen and cotton became established amongst the population compared with former convictions is demonstrated, amongst other things, by the English Wool Act. After this, between 1678 and 1824, the dead could only be buried clothed in sheep s wool, as this was believed to protect the living from the toxins released from the decomposing bodies. 6 7

The birth of qualitative clothing physiology Doctors carried out systematic wear tests on clothing for the first time in the 18th century. They held fast to the concept of cutaneous respiration, but also put forward a counter theory to Santorius, recommending that people wear textiles that were as light as possible with an open cell structure, in order to facilitate cutaneous respiration as far as possible. They regarded excessive perspiration as a result of clothing that was too warm as being responsible for diseases and as being detrimental to the organism as a whole. In a new paradigm shift, linen and cotton were once again portrayed as being superior to wool. With the discovery of oxygen and its connection to human respiration, the concept of cutaneous respiration as a central factor was called into question for the first time. In wear tests, on the other hand, the first aspects of wear comfort as we define it today were investigated: thermal insulation, the capacity to absorb moisture and the limit from which the material is perceived by the wearer as being wet. Between 1907 and 1920, the first systematic research into the connections between the physiology of the body and clothing was carried out, and the results of this still apply in principle today: The effect of cutaneous respiration is negligible. Thermal insulation does not depend on the fibres used, but on the construction (i.e. on the thickness, weave, porosity, airtightness of the textiles). Wickability is particularly important for the perceived wear comfort. Even with respect to wickability, it is not the fibre material itself which is important so much as the construction parameters. There are advantages and disadvantages to all fibre materials, depending on the specific wear situation. The dawn of a new age in the textile industry The development of the first synthetic textile fibres, Nylon (1935 by Dr. Wallace Hume Carothers in the USA) and Perlon (by the German chemist Prof. Dr. Paul Schlack in Berlin in 1938), represented the dawn of a new age in the textile industry: in addition to the traditional natural fibres, new materials were available for the first time whose properties could also be specifically influenced (figure 5). Against the background of the 2 nd world war, physicists, chemists, textile engineers and doctors, in particular in the USA, worked on the Figure 5: Synthetic fibres became available for garment manufacturing for the first time in the 1930s with Nylon and Perlon optimisation of clothing for the troops. For this, they investigated the interaction between body, climate and clothing using scientific methods. In doing so, they recognised for example the importance of design for the physiological function of clothing. Expertise made in Hohenstein Following the 2 nd world war, Prof. Dr.-Ing. Otto Mecheels was the first scientist in Germany to become involved in this field in his newly established Hohenstein Research Institute in Bönnigheim. It quickly became clear however that it was not possible to carry out an objective, scientifically based evaluation of comfort using wear tests on people alone (figure 6). Deviations in the results due to fluctuations in the environmental temperature, factors related to individuals etc. therefore needed to be eliminated using laboratory equipment, which simulated the physiological processes in the body as realistically as possible, but under controlled conditions which could be reproduced at all times. The first thermoregulatory transport model of the human skin (referred to as the Skin Model for short) to measure heat and moisture properties was developed by Prof. Dr. Jürgen Mecheels, son of Prof. Dr.-Ing. Otto Mecheels, in 1956 (figure 7). This marked the starting point of quantitative clothing physiology. However, with this first prototype of the Skin Model, unlike today, it was not possible to record the heat and moisture transport through the textiles separately, so the breathability could not yet be measured in physically defined terms. To record the interaction between body-climateclothing in quantitative terms, further measuring devices were therefore required. Under the aegis of Prof. Dr. Jürgen Mecheels, the first human thermoregulation model in Germany was developed. From 1968 onwards, measurements using Charlie 1 were used to complement clothing physiological parameters recorded to determine objective wear comfort (figures 8, 9, 10). Whereas it was only possible to test the textiles in the form of fabric layers using the Hohenstein Skin Model, measurements using Charlie 1 were carried out on ready-made garments. Figure 6: As there was no climatic chamber, wear tests were still carried out on a test track in the vineyards around Hohenstein in 1953. Figure 7: Prof. Dr. Jürgen Mecheels developed the precursor to the Hohenstein Skin Model as part of his dissertation in 1956. Figure 8: Prof. Dr. Jürgen Mecheels colleagues proudly demonstrate the only clothing robot in the world in 1968 (press text). Charlie 1 still has to manage without a head, hands and feet. From left: Dipl. Ing. Luthard, Siegfried Müller, Dr. Roland Schmieder, Renate Demeler, Franz Raab. Figure 9: In 1974, Charlie 1 appears with three models on the 25th anniversary of the Hohenstein Technical Academy [Lehranstalt Hohenstein e.v.] 8 9

Figure 10: The body of Charlie 1 consists of copper, which is painted black in order to simulate the thermal radiation behaviour of the human body as closely as possible. Charlie 1 was the first articulated thermal manikin in the world to perform a walking action. As the design and ventilation effects associated with movement have a considerable influence on the physiological function, this meant that reliable, practical conclusions relating to items Figure 11: Optimising the physiological function of clothing is particularly important in relation to situations involving extreme physical exertion, such as soldiers in battle. of clothing or clothing systems could be drawn for the first time. The thermal insulation of the items of clothing tested results from the amount of energy that needs to be transferred to the body of Charlie 1 in order to keep his skin temperature constant at given values. The birth of quantitative clothing physiology In order to be able to translate the data obtained using the Skin Model and articulated thermal manikin into the comfort perceived by man, Prof. Dr. Jürgen Mecheels and his colleagues carried out numerous wear tests on human subjects. Within research projects at the Hohenstein Institute for Clothing Physiology, which was founded in 1961, tests were carried out on a wide variety of materials and a range of climatic conditions and physical activity levels. Since 1962, a climatic chamber has been available in Hohenstein for this purpose, where a wide range of temperature and weather conditions can be simulated (figures 11, 12). In order to make it possible to translate to humans the data obtained using Charlie 1 and his successor, the technically improved Charlie 2 (figure 13), developed at the beginning of the 1970s, a so-called standard man (1.73 m, 70 kg) and standard woman (1.60 m, 60 kg) were defined. These are still used today with regard to body weight as a measure for the selection of suitable test subjects and as general reference values when presenting and interpreting clothing physiological data. The physicist Prof. Dr. Karl-Heinz Umbach (figure 14) significantly improved and extended the measuring methods used in clothing physiology as well as biophysical evaluation models from 1976 onwards. One of his first projects was the further development of the Hohenstein Skin Model. Using a porous sintered metal plate as a measuring surface, water vapour and fluid water were released in a controlled manner in a climatic chamber, thus simulating perspiration of human skin and different wear situations with different levels of sweat production. Moisture sensors between the measuring surface and the textile to be tested measure the buffer effect of the textile and how much water vapour can be transported from the body within a specific time. This modern measuring technique supplies more accurate and more detailed results. While the manual evaluation of the measuring data from a series of wear tests could previously take up to three months, computers were now able to complete this in just a few hours (figure 15). With Charlie 3 (post 1980), the bodyheat was no longer supplied using hot water, as with his predecessors, but using electric cables in the body. Its surface temperature was also controlled separately for the first time for 16 individual body segments. This took into account the fact that Figure 12: Since 1962, a climatic chamber has been available at the Hohenstein Institute for wear tests. This allows a wide variety of weather conditions to be simulated. Figure 13: At an experimental demonstration of the articulated thermal manikin, Charlie 2, the left leg was submerged in iced water and its thermoregulation readings were recorded. Figure 14: From 1976, Prof. Dr. Karl-Heinz Umbach (right) further developed the clothing physiological measuring methods developed by Prof. Dr. Jürgen Mecheels (left) and took over as head of this department in Hohenstein. Figure 15: Due to the complexity of the measuring results and the ever increasing amount of data involved, the Department of Clothing Physiology required its own computer centre at the beginning of the 1980s. 10 11

the temperature distribution on the human body varies considerably. In order to feel comfortable, this should be at around 30 ºC on the head and around 34 ºC on the trunk. The skin temperature should be around 32 ºC on the forearm, on the other hand. In order to offer optimum wear comfort, the thermal insulation of a garment should be segmented accordingly. Today, the fourth generation Charlie (figure 16) is in operation at Hohenstein and demonstrates an even higher degree of measuring accuracy than his predecessors due to the separation of the individual measuring segments using Teflon plates or strips, which makes it possible to separate the heat flow into the individual sections of the body. But even the now technically superseded Charlie 2 is still used in special circumstances such as the optimisation of marine survival suits its electrically-heated successors could short when swimming in ice-cold water. In 1986, scientists at Hohenstein developed a brother for Charlie 4 which was named Ralphie and sold to an American test and research institute, where he is still active today. The measure of all things Measurements using the Hohenstein Skin Model (figure 17) and the articulated thermal manikins, Charlie 2-4, (figure 16) now form standard tests in the field of clothing physiology worldwide. In Germany, Standard DIN 54101 has defined the measuring method using the Hohenstein Skin Model since 1991. This was replaced in 1993 by the international standards ISO 11092 and EN 31092. Today, the thermal insulation and relevant water vapour resistance (breathability) of a textile are not only measured in normal situations using the Skin Model to evaluate wear comfort; the buffering and transport capacity of vaporous and liquid sweat of the textiles during fairly heavy or extremely heavy sweating are also measured. Thanks to the fundamental research work by the Hohenstein Institute for Clothing Physiology, specification values for these parameters are known. Textiles must satisfy these values in order to effect good wear comfort, depending on the conditions under which they are used. In 1988, these clothing physiological specification values were incorporated in standards for protective clothing for the first time. DIN 61539, Weatherproof clothing was adopted, which was innovative in taking into account the clothing physiological demands of the wearers in the form of minimum breathability in addition to technological requirements of textiles for this type of clothing, such as impermeability to water, tear resistance etc. In 1998, this German standard was replaced by the European EN 343. As a result, since this time, specification values for wear comfort have been included in numerous other standards for protective clothing, e.g. in DIN 10524 for Workwear in the food industry, EN 469 for Protective clothing for fire fighters and EN 471 for High-visibility warning clothing etc. The overwhelming success of synthetic fibres Nyltest shirts with their extremely poor wear comfort gave synthetic fibres a bad image in the 1960s and subsequent years. Tests by Prof. Dr. Karl-Heinz Umbach proved however that with appropriate construction, also textiles made of synthetic fibres could not only enable heat and moisture management on the skin comparable to that of natural fibres, but could also offer superior results under many circumstances. On the basis of the research results from Hohenstein, the first doubleface textiles were developed at the beginning of the 1980s, whereby synthetic and natural fibres were combined with one another as two distinct layers. In 1980, an Austrian sports underwear manufacturer kitted out the national women s team for the Winter Olympics in Lake Placid with the world s first doubleface underwear, which was developed in conjunction with scientists at Hohenstein. The synthetic fibres lying against the skin transport perspiration quickly and effectively away from the body, while the outer cotton ensures a good buffering effect and evaporation of the moisture. Combined in this way, these two materials offer significantly improved wear comfort over cotton underwear, which was used previously, thanks to improved sweat transport which results in a drier feeling against the body and the more rapid drying of the material. Following the positive response of the Olympic athletes, the Transtex double Figure 16: As with his direct predecessor, the skin temperatures of the latest Charlie 4 are also controlled in 16 sections and the respective heat flow through clothing are messured it is therefore possible to make differentiated statements on the thermal insulation and physiological function of a garment. Figure 17:There are now seven Hohenstein Skin Models in Hohenstein s own laboratories, and 16 more devices manufactured by Hohenstein in service worldwide. 12 13

Figure 18: The doubleface underwear for the Austrian women s team at the Winter Olympic Games in 1980 in Lake Placid is now regarded as the first example of modern functional underwear. Source: Löffler Figure 19: Using a range of measuring methods, including determining the surface index, as shown here, skin sensory aspects of textiles are recorded and incorporated into wear comfort ratings as part of the physiological testing at the Hohenstein Institute face underwear was launched on the market for amateur athletes, too (figure 18). Its resounding success on the market marked the beginning of a period of popularity for functional textiles which is still continuing today, and which has led to ever increasing differentiation based on the intended use of the materials. Skin Polypropylene Cotton Wear comfort i s es-sense-tial In the early years of research into clothing physiology at the Hohenstein Institute, the skin sensory aspects of textiles, in other words the sensation of the textile against the skin, proved elusive. Back in the 1950s, its evaluation was already included in the scope of the survey with human test subjects, but with the same problems in terms of objectivity and reproducibility as with the thermophysiological evaluation. In the early 1970s, Sueo Kawabata from the University of Shiga Prefecture in the Japanese Hikone City was one of those who worked on devices that simulate the human sensation of touch. Using these, the subjective sense of touch, known as the textile hand, can be translated into exact physical parameters. Measurement of the shear stiffness has been shown to correlate extremely well with the subjective evaluation of fabric hand. When determining the shear stiffness, the force required to produce a parallel movement in a horizontally fixed textile strip is measured. As the sensation on the hands is significantly different to that on the body, the Japanese research results cannot be used as they stand to assess the skin sensory wear comfort of textiles. At the Hohenstein Institute, Prof. Dr. Karl-Heinz Umbach and his colleagues therefore analysed the influencing variables for the skin sensory perception and developed a new measuring and evaluation process: clothing which clings to skin which is wet with sweat, for example, is perceived as extremely unpleasant. Textiles worn close to the skin must therefore not cling to the skin surface as far as is possible. Napped textile surfaces and protruding fibre ends form natural spacers between the textile and the skin. Using several series of tests, the team of Hohenstein specialists defined a surface index using an image analysis system that expresses the number and length of these spacers as a numerical value (figure 19). The value of this surface index must lie between 3 and 15 in order to effect good skin sensory wear comfort. Using modern image editing on the computer, the number of contact points between the textile and the skin was measured. This shows whether the textile is perceived to be unpleasantly cold and damp or wet when perspiring. In order to evaluate the effects which arise when the textiles rub against the skin when moving, Prof. Dr. Karl-Heinz Umbach developed a measuring device whereby the textile material to be tested is drawn in a controlled manner over a sintered glass plate which releases water from its pores as a skin simulator. An wet cling index is determined from the force required for this. The numerical value indicates whether the textile clings to the skin during perspiration. The stiffness of the textile is measured as another influencing variable affecting skin sensory wear comfort. For this, the bending angle of a strip of fabric placed on a thin bar is determined in a measuring device using a laser beam. Here, too, the decades of experience of the Hohenstein scientists help to define specifications for various product ranges and fields of application that are used to help prevent mechanical skin irritation due to the excessive bending rigidity of the material. As damp skin is more easily irritated mechanically than dry skin, it is also important that clothing worn close to the skin can transport fairly large quantities of sweat rapidly to layers further from the skin. The sorption index indicates how quickly a textile material is able to absorb liquid sweat and transport it away from the body. To determine this, Prof. Dr. Karl-Heinz Umbach developed a special video-based, continual contact angle measurement for a drop of water that is placed in a defined way on the textile surface (figure 20). This makes it possible to accurately determine how long it takes for the water to totally penetrate into the material. High marks for wear comfort Thanks to the laboratory tests developed, a wide range of key textile data has been available at the Hohenstein Institute since the middle of the 1980s for the evaluation of the wear comfort of textile fabrics. From this, it has been possible for specialists to evaluate individual aspects such as the breathability of a material and provide construction guidelines for their optimisation. Prof. Dr. Karl-Heinz Umbach s aim is subsequently to combine the individual parameters to make an overall statement regarding the wear comfort of a textile. This wear comfort rating ranges from 1 (= excellent) to 6 (= inadequate) following the German school grading system, and provides a quantitative assessment of the physiological quality of a textile product, as well as making it possible for those who know little about textiles to make direct product comparisons based on wear comfort when making a purchase. Figure 20: Using the continual contact angle measurement of a drop of water on the textile surface, it is possible to calculate how fast the material absorbs liquid sweat 14 15

Figure 21: The Hohenstein Quality Label for the Wear Comfort Vote to document the physiological quality of clothing at the Point of Sale. Figure 22: During the night, bed components must transport around ¼ litre of sweat away from the body of the sleeper while at the same time keeping the microclimate in the sleeping pocket stable within a range perceived to be comfortable even when the environmental temperature varies. The combined experience of the Hohenstein specialists over a number of decades is utilised in particular when developing the different mathematical formulae that provide the wear comfort rating. These formulae differentiate the type of clothing and the wearer s level of activity and are based on the textile parameters measured using the Skin Model and skin sensory devices. Since 2003, manufacturers and retailers have also been able to advertise the wear comfort rating on the product itself, e.g. as a hang tag or printed onto the packaging (figure 21) using the Hohenstein Quality Label. In conjunction with other parameters tested, such as freedom from harmful substances or the use of nanotechnology, objective and farreaching quality statements can be made for a product and communicated to consumers. As you make your bed It is not only those around the world who wear clothing who benefit from the findings of the Hohenstein Institute in the field of clothing physiology anyone who uses bed linen, encasings (for those allergic to house dust mites) moisture transfer buffer effect heat production heat transfer and duvets also benefits from improved sleep comfort. When evaluating the sleep comfort of duvets, the focus is on the temperature balance of the human body in relation to the environmental temperature and the heat and moisture management within the sleeping pocket (figure 22). A physiological sleep comfort rating ranging from 1 (= excellent) to 4 (= unsatisfactory) can be calculated for duvets. Similar to the wear comfort rating for clothing, this makes a statement on the ability of the product to maintain a pleasant body temperature when in bed or asleep, and to quickly and effectively transport any sweat away from the body. The thermal insulating effect of a duvet plays a particularly important role in temperature management. The guiding principle of earlier years, the thicker and heavier the duvet, the better the level of thermal insulation, has been disproved by tests at Hohenstein (figure 23). In contrast, the objective of research in this field today when developing a modern duvet is to achieve thermal insulation suited to the individual s needs with a duvet that is as lightweight as possible. In order to simplify guidance for retailers and consumers, the scientists at Hohenstein defined three thermal insulation classes for duvets in 1999 based on their tests. Using a graph displayed in specialist bed retailers (figure 24), the customer can identify the most appropriate thermal insulation class based on the nighttime temperature in his bedroom and his personal body weight. This is higher, the lower the environmental temperature and body weight of the sleeper. Whereas someone weighing 50 kg generates body heat of only 62 Watts, someone weighing 110 kg would generate 101 Watts. As both individuals require the same skin temperature to feel comfortable and maintain body functions during sleep, the thermal insulation of the duvet must be significantly higher for the individual with a lower body weight. The Hohenstein Quality Label also provides information on the thermal insulation class of a duvet (figure 25). Naturally, a duvet does not only have to have optimal thermal insulation, it also needs to be able to effectively transport excess sweat away from the body of the sleeper. This is expressed in the sleep comfort rating that is determined using a prediction model developed at Hohenstein from measurements using the Skin Model and the articulated manikin, Charlie 3. Two sleep comfort ratings for duvets are stated on the Hohenstein Quality Label, one for warm and one for cold environments (figure 25). The crucial factor for deciding whether the rating for a warm or a cold environment needs to be taken into consideration when purchasing a product is the room temperature during the period in which the product will be used (summer, winter, all-year round) and the individual weight of the buyer. The graph shown in figure 24, which is displayed in specialist retailers, once again helps in making the correct choice. For example, for an individual weighing 80 kg with a bedroom temperature above 18 C throughout the year, the rating for a warm environment is key. If the temperature is below this throughout the year, the rating for a cold environment should be taken into account when selecting a product. If an all-year duvet is required for extremely varied room temperatures, both ratings must be taken into consideration. Freezing in a sleeping bag? When purchasing a sleeping bag, the most important factor is the minimum environmental temperature at which this can be used without feeling cold. Charlie 3 provides the answer to this question, too. He is used to measure the effective thermal insulation of the sleeping bag for the sleeper in a climatic chamber under defined conditions (figure 26). In an extensive research project, scientists at Hohenstein developed a physiological evaluation model in the early 1990s that could be used to derive the thermal range of utility of a sleeping bag from these thermal insulation values. The lower limits for this were the comfort and limit temperatures at which the standard woman or standard man begins to feel cold in the sleeping bag. At the even lower extreme temperature, the standard woman would suffer from hypothermia. The maximum temperature at which the sleeper sweats excessively forms the upper limit for the range of utility of the sleeping bag. Body weight in kg TK cold TK warm Thermal insulation Ambient temperature in C Figure 23: The thermophysiological properties of duvets or mattresses are measured using the articulated manikin Charlie 3. Numerous sleep tests with human test subjects confirmed the results of laboratory tests and the assessment of sleep comfort derived from this. The climatic chamber makes it possible to simulate a wide range of environmental temperatures. Figure 24: Using the body weight of the sleeper and the temperature in the bedroom, the required individual thermal insulation class of the duvet can be derived and a decision can be made as to which of the two sleep comfort ratings given on the Hohenstein Quality Label is relevant for this temperature. Figure 25: For duvets, the Hohenstein Quality Label provides information on the front and reverse on the thermal insulation class and sleep comfort ratings in warm and cold environments. 16 17

This measuring and evaluation method was incorporated in the German standard DIN 7943-1 in 1995. This was replaced in 2002 by the European standard EN 13537. Sleeping bag manufacturers and retailers are now able to provide temperature information for their products on an objective and scientifically proven basis and are no longer dependent on pure speculation. Many sleeping bag manufacturers or retailers therefore have their products tested at the Hohenstein Institute. These tests are now particularly significant, as the Product Liability Act passed throughout Europe in 2005 makes the sleeping bag manufacturer or retailer liable for the accuracy of the thermal limits stated for the range of application. Comfort mobilises Thermophysiological comfort of vehicle seats plays a crucial role in road safety: Scientific findings show that the performance of a driver over long distances significantly decreases if the car seats do not adequately support heat and moisture balance as well as posture. This leads to exhaustion and loss of concentration, which in extreme cases, could result in serious accidents. Only if the material and design of a seat are optimally coordinated, thus forming what is known as a ventilation effect between the body and the seat, will the driver enjoy optimum seat comfort. Otherwise, heat and moisture can accumulate, which not only feels unpleasant but can also have a negative effect on the driver, both physically and mentally. Numerous test with volunteers using a driving simulator in a climatic chamber (figure 27) have demonstrated that, from a physiological point of view, the seat comfort is affected by the following four parameters: the initial heat flow, determining by the sensation of warmth in the first few minutes after sitting down; the thermal insulation adjusted to the climate in the vehicle interior; the ability, known as breathability, to transport any perspiration formed away from the body as quickly as possible; and the extent to which the seat is able to absorb water vapour without feeling damp from a subjective point of view (moisture buffering). The breathability and moisture buffering of the seat is determined using the Hohenstein Skin Model, and the initial heat flow and thermal insulation are measured using an Upholstery Tester. With this device, in order to simulate the heat lost from the human body, an aluminium stamp in the form of a human bottom, heated to skin temperature, is pressed down onto the seat (figure 28). Heat flow sensors provide information on how much heat the individual releases in the first minutes after contact with the cold seat and on the thermal insulation provided after a thermal equilibrium has been achieved between the body and the surface of the seat. Many well-known car manufacturers and their suppliers have been using the services of the Hohenstein specialists for a number of years now to improve the quality of their seats. The next task of the Hohenstein scientists in the field of vehicle seats is likely to be research into construction elements for an active climate seat which will always provide a pleasant microclimate on the contact surfaces of the body by means of sensor-controlled heating and cooling elements. Children are more than just small humans Due to the lower mass of a child s body it can only produce less thermal energy than the body of an adult. In addition, children s thermo-regulation ability is by no means fully developed, meaning that the body may react slowly or may not react at all to changes in ambient temperature. What is more, all their sweat glands have yet to become active. As a result, the risk of becoming chilled or overheating is disproportionately greater than it is for adults. These physiological differences are especially important for the construction of bedding. With the help of Charlene, a thermally Figure 26: The articulated manikin, Charlie 3, measures the thermal insulation of sleeping bags according to the standard EN 13537. This is used to determine the thermal range of application of the sleeping bag. + 20 C 0 C - 6 C - 13 C Comfort zone Transition zone Risk zone Figure 27: Using test subjects, the physiological comfort of vehicle seats is also tested in the climatic chamber using a driving simulator. Figure 28: The Upholstery Tester measures the initial heat flow when first sitting down on the vehicle seats as well as the effective thermal insulation while driving. 18 19

Figure 31 on the left: Thermoregulation models of the human hand are used to measure moisture and heat emissions in order to assess the wear comfort of gloves under realistic conditions. Figure 30: A thermoregulation model of a child about four-years-old is used at the Hohenstein Institute to test and optimise the sleep comfort for children's bedding in particular. Figure 32 on the right: In order to investigate the thermal wear comfort of socks and shoes, the special wearing conditions featured by the human foot must be taken into consideration. Figure 29: Children s thermoregulatory systems are quite different from those of adults. As a result, the thermally segmented test mannequin Charlene was brought into service at the Hohenstein Institute in 2008. segmented mannequin developed at the Hohenstein Institute, the sleeping comfort of children s bedding can be evaluated and optimised with respect to the special physiological needs of children. Charlene simulates the heat generated by the human body, just as her adult counterpart Charlie 4 does with the aid of a computer-controlled heating system. And just as is the case with their human role models, Charlene, who weighs 20 kilograms and is 92 centimetres tall, produces far less heat than Charlie 4, who weighs in at 75 kilograms and is 175 centimetres tall. Therefore, for a child to stay comfortably warm beneath the bedcovers, the amount of thermal insulation of children s bedding must be increased accordingly. Unlike Charlie 4, Charlene is made of synthetic materials rather than copper. A computer-controlled heating system makes it possible to regulate independently the heat generated by six different segments of the body. The rule of thumb here is that the more heat a body part generates meaning more energy is required in that segment to maintain target skin temperature, the lower the level of heat insulation provided by the blanket for that segment. In addition to its insulating effect, the sleeping comfort of bedding is defined by its capacity to absorb perspiration and draw sweat away from the sleeper effectively. Because Charlene does not sweat, the measurements she contributes are combined with those from the Hohenstein skin model. The skin model enables assessments of moisture transport resistance as a measure of breathability, and perspiration transport, sweat buffering, and drying time of the textile materials used as well. The battle against cold hands and perspiring feet In cooler ambient temperatures, the large surface areas of skin on the fingers and toes lose far more heat relative to their weight than say, for example, is lost from a person s trunk. In order to maintain comfortable skin temperatures for these parts of the body, the thermal insulation of socks, shoes and gloves must be accordingly high. At the same time, the processed textile materials must absorb sweat and draw perspiration away from the body very effectively, particularly during physical activity. In the sweating hand and sweating foot models, the functional principles of the skin model and thermally segmented testing mannequins have been combined, i.e. they generate both moisture and heat. For the first time, this allows researchers to simulate as realistically as possible the special thermal characteristics of human extremities. Up until now, all the materials used in shoes and socks had to be tested individually with the aid of the skin model as well to assess reliably the wearing comfort of these combinations. Extrapolation scenarios for garments, however, nevertheless allowed for values approaching actual data. Reliable, and above all differentiated, assessments for individual areas of the foot are now possible with the aid of the sweating foot. The sweating hand and sweating foot are constructed in markedly different ways. The thermo-regulation model of the human hand simulates the human hand with a membrane-like material that is permeable to moisture and emits moisture along its entire surface. The sweating foot is made of thirteen metal parts and sweat is emitted from 32 individual valves. In order to account for the major role ventilation plays in the thermal comfort of footwear, motorised fans were used to simulate the aerodynamic effect of walking by moving air around the sweating foot. One thing all the clothing physiology measuring equipment has in common is that the lion s share of development time was devoted to implementing complex control and measurement technologies. In order to measure precisely the amount of perspiration emitted and the energy required to maintain a comfortable skin temperature, the team led by Professor Karl- Heinz Umbach had to move into technologically and scientifically uncharted territory as they designed the thermally segmented mannequin Charlie 4 and the Hohenstein skin model. Now manufacturers world-wide can profit from the knowledge they gained ultimately leaving consumers to enjoy optimised textile products whether they are relaxing or on the job. Clothing physiological measurement methods at a glance In testing the wearcomfort of textiles, a fundamental distinction is made between thermophysiological aspects i.e. the management of warmth and moisture, and how the textile feels on the skin (skin sensibility). 20 21

Figure 33: The Hohenstein Skin Model consists of a sintered, porous metal plate that can be warmed electrically and to which water is supplied. Thermo-physiological measurement methods The Hohenstein Skin Model The Hohenstein Skin Model simulates the way the skin emits heat and moisture. It consists of a sintered, porous metal plate that can be warmed electrically and to which water is supplied. It is located in a climate-chamber, a space where the most diverse environmental conditions can be simulated. Temperature, humidity and the movement of air can be set as desired. For substances and fabrics, measurements taken using the skin model supply specific parameters such as, for example, thermal insulation and moisture transport resistance a measure for breathability, perspiration transport and sweat buffering, and drying time, etc. These parameters characterise the thermo-physiological quality of textile materials Thermally Segmented Testing Mannequins Charlie 3, Charlie 4 and Charlene The thermal insulation of ready-made garments, bedding and sleeping bags can be measured with the help of the thermally segmented testing mannequins Charlie 3, Charlie 4 and Charlene who were also developed at the Hohenstein Institute. Using what are known as human thermoregulation models, the heat generated by adults and children is set. The segmented mannequins are made of copper or synthetic materials and have been fitted with a computer-controlled heating system that allows the heat generation for different parts of the body to be regulated individually and independently of one another. The more heat emitted from the arms or legs, for example, the worse the thermal insulation of the garment is for those areas of the body. These figures are very significantly influenced by the movement of air when the body is in motion. Therefore the segmented mannequin Charlie 4 has been set up so he is able to move during testing as if he were out for a brisk walk. The assessments made using the thermally segmented testing mannequins are an important complement to those made using the skin model, because the influence of the way the item or garment is made (fit, elasticised cuffs, turtlenecks, etc.) can be taken into consideration. But because the Charlies and Charlene can do all this without breaking a sweat, moisture management and with it a significant aspect of thermo-physiological wear comfort can only be evaluated when the results of tests made on the skin model are available to use as a basis. Thermal regulation models sweating hand and sweating foot In the sweating hand and sweating foot models, the functional principles of the skin model and the thermally segmented testing mannequins have been combined, i.e. emissions of heat and moisture in controlled climatic conditions. With the measuring instruments that came into operation at the Hohenstein Institute in 2008, the thermal insulation and breathability of gloves, socks and shoes can be evaluated. Upholstery Testing Device Whether a car is parked outside in winter or in the summer sun, it always takes awhile for the seats to become comfortable. By using an upholstery testing device, it is possible to measure the impression of temperature (initial heat flow) that a person has when they first make contact with the car seat. In addition, the thermal insulation of the seats can also be tested during longer trips made in the most varied of surrounding temperatures. Human Test Subjects Thermo-physiological comfort can be objectively measured and assessed with the Hohenstein Skin Model and the thermally segmented test mannequins Charlie and Charlene. In order to develop these testing methods and the assessment models that have become established world-wide in the sector of clothing physiology today, it was necessary to run numerous series of tests on human test subjects. They still come to the Hohenstein Institute even today if a completely new product is being developed or to confirm the results of tests carried out using the skin model and the thermally segmented test mannequins. Climate chambers The most varied of environments can be created in the climate chambers at the Hohenstein Institute. Temperatures can range from - 25 C to + 50 C making, for example, testing sleeping bags possible under extreme conditions. A precipitation system can be used to create rain of a wide-range of intensities, and a warm wall simulates intense sunshine or heat as real as that from open fire, especially when it is a matter of testing the wear comfort of fire-fighters clothing. Fans, a driving simulator used by people testing car seats, and basins in which Charlie 3 is immersed in order to assess the survival time of pilots in extreme conditions, such as submersion in ice water, round out the standard equipment of the Hohenstein climate chambers. Measurement methods for skin sensibility Along with the heat and moisture management characteristics of textiles, skin sensibility is one of the significant aspects that influences wear comfort. Garments worn close to the skin should not cling to its surface. It should also transport large amounts of perspiration to layers of clothing further away from the skin. In order to meet the comfort standards dictated by skin sensibility, the construction of the textile base material of which the garment is made has the most relevant role to play. To assess the surface structure of textile substances in order to gauge their comfort in terms of skin sensibility, a number of different laboratory tests have been developed at the Clothing Physiology Department of the Hohenstein Institute. Figure 34: Ongoing test series at the thermal regulation model sweating foot. Figure 35: Only through numerous experiments with human test subjects during the past decades has it been possible to make the extrapolations required to correlate human perceptions with laboratory results. Series of tests with volunteers are in the meantime primarily limited to the evaluation of completely new products and confirmation of tests carried out on the skin model and thermally segmented test mannequins. Figure 36: Fans, warm walls, etc. are used to simulate the most varied of climate conditions in the four climate chambers of the Hohenstein Institutes. 22 23

Figure 37: The speed at which the material absorbs perspiration is detected with the aid of continual measurement of the contact angle of a water droplet on the surface of a textile. Cling index A porous, sintered plate of glass to which water is supplied using a calibrated motorised burette simulates perspiring skin. The textile specimen is fastened to a cylinder and pulled across the plate.the force required to do this supplies what is called the cling index, which is used to evaluate whether the textile will cling uncomfortably to the skin when the wearer is sweating. Number of contact points and surface index A surface scanner, or alternatively, a microscope linked to an image analysis system shows the number of contact points for the textile and surface index. This indicates how much the contact surface the textile material has with the skin and the hairiness of its surface. During decades of research, the scientists at Hohenstein have defined threshold values for the optimum number of contact points and the surface index. Stiffness For determining the stiffness or bending angle of a textile substance a laser measurement is taken on a strip of fabric that has been placed on a thin bar. Based on their years of experience, the scientists at Hohenstein have defined standards for products and areas of use that guarantee optimal wear comfort and rule out mechanical skin irritations caused when stiffness is too great. Sorption index Skin becomes more sensitive to mechanical irritation as moisture increases. As a result, it is advantageous for sensitivity and wear comfort when a textile substance transports perspiration away from the skin as quickly as possible. The sorption index is the speed at which a textile absorbs the drops of water with which it comes into contact. A drop of water is placed on the textile specimen and observed using a video camera. The angle of contact of the drop of water on the textile s surface is continually monitored and recorded, indicating how quickly the material is able to absorb sweat. Figure 38: A porous, sintered plate of glass to which water is supplied using a calibrated motorised burette simulates perspiring skin. The textile specimen is fastened to a cylinder and pulled across the plate. The force required to do this supplies what is called the cling index, which is used to evaluate whether the textile will cling uncomfortably to the skin when the wearer is sweating. One mark for wear comfort The results of the tests carried out on the skin model and thermo-regulation models all come together with assessment of skin sensibility to make up one grade known as wear comfort or sleep comfort. This is possible because research results have shown, that, for example, in the case of garments worn daily, thermophysiological characteristics account for about 66% percent and skin sensibility for about 34% of perceived wear comfort. Evaluation of wear comfort is done according to the German school grading system, where 1 is very good and 6 is unsatisfactory. The comfort marks are used today by numerous manufacturers in the form of the Hohenstein Quality Label. These are attached to the product and allow the consumer to make a simple comparison between different products. Figure 39: A series of measurement methods are used to assess the skin sensibility characteristics of textiles within the scope of the physiological tests at the Hohenstein Institutes. Among them are the measurement of stiffness, which is recorded and included together with other measurements to determine wear comfort. 24 25

Thermo-regulation model Charlie 4 A "standard" adult male Charlene A "standard" fouryear-old child Hohenstein Skin Model Height/Weight/Size 175 cm, 75 kg 92 cm, 20 kg 20 cm x 20 cm in a climate-chamber Measurements Thermal insulation Thermal insulation Thermal insulation Moisture transport resistance (breathability) Sweat buffering Perspiration transport Products tested Material and colour Heating system Ready-made products: garments of all types, bedding and sleeping bags Copper painted black, to simulate the physical heat generation of the human body as closely as possible Individually controlled electric heating elements in 16 segments, for evaluation of thermal insulation for different parts of the body Ready-made products: children's bedding and sleepwear Plastic with a black coating, to simulate the physical heat generation of the human body as closely as possible Individually controlled electric heating elements in 6 segments, for evaluation of thermal insulation for different parts of the body Sweating Hand Human skin Human hand Human foot Fabrics: textile materials of all types Sintered metal plate Electric heaters Sweating Foot Glove size 9 Shoe size 43 Moisture transport resistance (breathability) Ready-made products: gloves Membrane material stretched over a wire frame Hot water circulating systems Thermal insulation Moisture transport resistance (breathability) Ready-made products: socks and sock-shoe combinations Metal segments Individually controlled electric heating elements in 13 segments, to evaluate thermal insulation for different parts of the foot Measurement points In 16 segments In 6 segments In a segment In a segment In 13 segments Perspiration None None Vaporous, through pores on the entire surface due to the partial pressure differentials of water between the skin model and the surroundings Liquid across the entire surface through spray valves Mobility Complete range of motion for all "human" joints. To account for the movement of air around a person walking, these motions are simulated when testing garments. Complete range of motion for all "human" joints. Walking movements are not yet simulated due to the items that are currently being tested Stretching as well as static and dynamic pressure on the material (such as car seats for example) can be simulated Via membrane material due to the partial pressure difference of moisture between the sweating hand and its surroundings None Via 32 sweat valves aided by a medical (water) pump Walking is simulated Prof. Dr.-Ing. Otto Mecheels Director of the Hohenstein Institute 1946-1962 1894 Born in Bönnigheim (Germany) 1929-1929 Head of dyeing at Amann & Söhne in Bönnigheim 1929 Appointed Professor at the Staatliche Technikum für Textilindustrie [State technical school for the textile industry] in Reutlingen where he took charge of the department of textile chemistry 1935 Transferred to the Preussische Höhere Schule fur Textilindustrie Mönchengladbach as school principal 1944 Following the destruction of the school in Mönchengladbach, returned to Bönnigheim with the teachers and students in their final year. The around 60 people initially made use of the empty rooms in the castle there at the end of the war, they moved into the nearby Hohenstein Castle. 1946 Founded the Hohenstein Research Institute [Forschungsinstitut Hohenstein] as an independent company, together with his wife, Lisel 1949 The Lehr- und Versuchsanstalt für die Bekleidungstechnik [Education and Research Institute for Clothing Technology] is founded. This was renamed the Lehranstalt Hohenstein e.v. in 1954 1961 The Hohenstein Institute for Clothing Physiology [Bekleidungsphysiologische Institut Hohenstein e. V. (BPI)] is founded as a publicly-funded interdisciplinary research institute 1962 Handed over leadership of the Institute to his son, Prof. Dr. Jürgen Mecheels 1979 Died at the age of 85 at Schloss Hohenstein Prof. Dr. rer. nat. Jürgen Mecheels Director of the Hohenstein Institute 1962-1995 1928 Born in Stuttgart (Germany), the son of Prof. Dr. Ing. Otto Mecheels 1958 Degree in textile chemistry at the University of Heidelberg 1961-1961 Doctorate and development of a thermoregulatory functional model of the skin (Skin Model) 1961-1962 Worked as a scientist at the Hohenstein Institute and a lecturer at the Hohenstein Technical Academy 1995-1995 Head of the Hohenstein Institute 1988 Appointed professor by the Minister President of Baden-Württemberg, Dr. Lothar Späth 1996 Awarded the Cross of the Order of Merit of the Federal Republic of Germany 2006 Died at the age of 78 Prof. Dr. rer. nat. Karl-Heinz Umbach Head of the Department Clothing Physiology at the Hohenstein Institute (1976 - September 2009) Deputy Head of the Bekleidungsphysiologisches Institut Hohenstein e.v. (1995 - September 2009) 1944 Born in Stetten/Remstal (Germany) 1971 Degree in physics at the University of Stuttgart 1971-1976 Research assistant at the 2. Physikalisches Institut at the University of Stuttgart 1975 Doctorate in the field of solid state physics Since 1976 Employed at the Hohenstein Institute: around 190 publications in the field of clothing physiology Since 1982 Chairman of four and member of 15 national and international standards committees (e.g. for protective clothing) 1995 Adjunct Professor at the North Carolina State University, Raleigh NC, USA 1996 Honorary professor at the University of Kassel Dr. rer. nat. Andreas Schmidt CEO of the Department Function and Care at the Hohenstein Institute (October 2009 - November 2017) 1974 Born in Monheim am Rhein 1999 Degree in chemistry at the Heinrich-Heine-University, Düsseldorf 1999-2002 Research associate at the German Textile Research Center North-West e.v., associated institute to the Gerhard-Mercator-University Duisburg 2002-2008 Head of laboratory at Henkel KGaA, Laboratory: Textile Fibers 2008-2009 Several functions in the field of product development at Henkel AG & Co. KGaA Since 2009 Director of the Department Function and Care at the Hohenstein Institute 26 27