82 science in clothing comfort

82. Science in Clothing Comfort Số trang: 185 trang Ngôn ngữ: English -------------------------------- Description Clothing comfort is one of the most important attributes of textile materials. This book starts with an introduction to clothing comfort discussing comfort and the wearer’s attitude, and human–clothing interactions. Chapters go on to discuss related aspects including psychology and comfort, neurophysiological processes in clothing comfort, tactile aspects, thermal and moisture transmission, and garment fit. Science in clothing comfort is an essential reference for fibre, fabric and clothing manufacturers alike.

in Clothing Comfort

Apurba Das and

R Alagirusamy

New Delhi ● Cambridge ● Oxford

Woodhead Publishing India Pvt Ltd., G-2, Vardaan House, 7/28, Ansari RoadDaryaganj, New Delhi – 110002, India

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First published 2010, Woodhead Publishing India Pvt Ltd

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Preface vii

2.1 Psycho-physiological factors of clothing comfort 13

2.4 Psychological aspects of aesthetic comfort 23

3.4 Physiological requirements of the human body 48

4.2 Fabric handle attributes for expressing tactile comfort 584.3 Assessment of fabric handle characteristics 594.4 Fabric parameters affecting tactile sensation 73

5.4 Thermoregulation through clothing system 82

5.6 Transient heat flow and warm–cool touch of fabrics 915.7 Measurement of thermal transmission characteristics 945.8 Parameters for expressing thermal characteristics 995.9 Thermal transmission characteristics of fabrics 100

6.2 Liquid water transfer: wicking and water absorption 107

6.5 Evaluation of moisture vapour transmission 124

7.2 Combined heat and moisture interactions with textile materials 1377.3 Factors affecting heat and mass transfer through fabrics 1447.4 Evaluation of heat and mass transmission 1487.5 Parameters expressing heat and mass transmission 154

There are many textbooks describing different aspects of clothingtechnology and sciences of human comfort However, there are not manybooks giving a survey of the sciences of comfort and clothing technology

in one volume In this respect, this book would fulfill the need ofundergraduate and postgraduate students who are studying various aspects

of textiles and clothing and also the researchers who are working in thearea of clothing comfort The undergraduate and post graduate students oftextiles, clothing and fashion or home science generally study about thebasics of fibres, yarn formation, fabric formation, apparel production andtheir evaluation techniques But the engineering of right type of garment/clothing for any specific application is possible only when we understandthe interrelationship between the clothing requirements and human comfort.The text in this book describes the aspects of science in perceiving thecomfort by the human being and the science and technology of clothingthat deals with the comfort The first chapter consists of the details ofcriteria for the selection of clothing, components of clothing comfort,human clothing interaction and scientific understanding of clothingcomfort The second chapter provides the information on the perception

of clothing comfort by human sensory system and psycho-physics involved

in the perception and assessment of comfort, psychological aspects ofclothing comfort, etc In third chapter, the sensory systems of human,interpretation of the signals by nerve and brain for each sensation related

to comfort and details of mechanical and thermal receptors present in theskin are described The fourth chapter consists of the detailed survey ofaspects of tactile comfort, fabric parameters that affect the tactile sensationand fabric handle and evaluation In fifth chapter, the thermo-regulationsystem in human body and through clothing system, effect of thermaldistress, transient heat flow for warm–cool sensation and evaluation offabrics for thermal characteristics are detailed The sixth chapter describesthe liquid water transfer through fabrics, evaluation of liquid water transfer,principles of moisture vapour transfer and its evaluation by variousmethods The seventh chapter consists of the survey of the combined heatand mass transfer through textile materials and its evaluation The last

chapter deals with the sciences of comfort with the size and fitness ofgarment.

In this book, not only the scientific and technical information, but alsoother related basic information at each level is given to understand theconcepts clearly References to original sources have also been given tofollow the literature that will be useful for the readers The undergraduate,postgraduate and research students from textile engineering, fashiontechnology, clothing and apparel technology, home science will bebenefited from this text book This book also provides the guidelines such

as comfort level of the person at various activity levels and at variousclimatic conditions, etc which are needed to produce the functionalgarments for various applications So, this book would be also useful forthe industries which are involved in the production of functional garments.The authors are indebted to QIP/CEP of IIT Delhi and faculty board ofthe department of textile technology, IIT Delhi for giving necessarypermission and providing financial support The authors are thankful totheir colleagues in the department for their support They are also thankful

to their students for all the help during literature search, writing and editing

of the book The authors would also like to express their appreciation toWoodhead Publishing India Ltd for editing and publishing of this book

It is hoped that the students, teachers and researchers will be able to getthe idea of science behind the clothing comfort with the help of this book.There may be some shortcomings in the book and the authors welcomethe comments from readers and these constructive comments will be useful

in bringing out the second edition of the book

Dr Apurba Das

Dr R Alagirusamy

We have been encouraged in this venture by many people and wouldlike to acknowledge the considerable support we have received We wouldlike to thank Woodhead Publishing India Ltd for recognizing the need for

an up-to-date account of sciences of comfort in clothing, seeing it as anexciting field that has much to offer to the students and researchers Wewould also like to thank the quality improvement program (QIP) of ourinstitute for support We are also indebted to our students for their excellentcoordination, organizational skills and effective liaison during ourmanuscript preparation We are grateful to many of our teachers andmentors for their education and endorsement

Dr Apurba Das

Dr R Alagirusamy

Introduction to clothing comfort

The basic needs of human are food, clothing and shelter After fulfillingthe first need of food, a person looks for the second important need, i.e.clothing In the present day society, we expect much more from clothingthan to satisfy our basic need In most societies the clothing is for thepurpose of expressing wealth, status, occupation, age, occasion, gender,etc [1] There are various factors which influence the selection of clothingtype Figure 1.1 illustrates the important factors which influence theselection of clothing It is evident from Fig 1.1 that the factors whichinfluence the selection of clothing can be divided broadly into four majorgroups, i.e social factor, economic factor, environmental factor andphysical factor All these factors play significant roles in selection ofclothing of a person

The social factors include the place where a person lives (urban or ruralarea), cultural background of person, gender, occupation, occasion, socialstatus, etc Depending on the place where a person lives, the clothing patternchanges In urban area, due to close cultural interactions between thevarious sections of people, the clothing pattern becomes more cosmopolitan

in nature But on the other hand the rural clothing is more influenced bythe regional factors Similarly, clothing is also influenced by culturalbackground and upbringing of a person The upbringing influences thetaste of a person toward the clothing significantly The modern societydoes not believe in gender biasness and strongly oppose this But, are weready to accept this to be applied while selecting clothing? Except fewexceptions, we are still comfortable in maintaining differences in maleand female clothing In some cases a person selects his clothing depending

on the occupational requirement For example, one can easily make outthe difference between a police and a common man depending on hisclothing, or in a hospital a nurse can be easily identified based on herclothing We generally prefer to wear different clothing depending on theoccasion, namely formal wear, casual wear, etc A person generally prefers

1.1 Factors affecting the clothing selection.

to wear formal clothing in office, but the same person prefers casual wear

in leisure trip It is also very common that a person tries to show his socialstatus through clothing, this trend prevails in every society since thebeginning of the civilization The kings always tried to differentiatethemselves from the common man by wearing royal clothing

Among the economic factors the important components are economiccondition of society, economic status of individual and availability oftechnology or raw material When the economic condition of societychanges that also reflects through clothing It is well-known fact that thegeneral clothing pattern of rich and poor sectors of society differs and it

is obvious This is also true for individual Each individual selects clothing

Social status

Climatic condition Protection from extreme

conditions

Unusual places (deep sea, space, etc.)

Age of a person condition of a Health

person

Physical structure

of body

physiological responses of body

Thermo-Activity level

Factors for clothing selection

Physiological factors

factors

Economic factors

Socio-economic

condition

Economic status of an individual

Availability of technology / raw materials

Rural /

Urban background Cultural Gender Occupation Occasion

depending on the affordability Person also selects clothing to show hiseconomic status The availability of a particular type of clothing dependsmainly on the availability of technology and raw materials These twofactors are directly or indirectly dependent on the economic situation andaffordability of the society.

The environmental factors include climatic conditions (too cold, toohot, raining, chilled wind, etc.), protection from extreme environment,unusual places (space or under water), etc Depending on the environmentalconditions the clothing need changes Here, the performance factors arethe dominating parameters One requires different clothing for differentclimatic conditions A person, going to extreme cold place, will definitelylike to protect himself from extreme cold by wearing extreme coldprotecting clothing But, the same person will not use the same clothing innormal environment Depending on the climatic temperature the garmentsare broadly divided into two categories, namely winter wear and summerwear Similarly, in rainy days we require clothing which is waterproof.Clothing pattern also changes depending on the environmental threat, likeexplosives, poisons, biological attacks, fire, radioactive or ultraviolet rays,etc Clothing also has to withstand falling and flying objects in certaincircumstances Depending on the needs of unusual places, like deep undersea, space etc., the type of clothing changes In these places the specialtype clothing are required for protection and specific performance.The last and very important factor is physical conditions of a person,which include age, condition of health of person, body structure,physiological response of body, activity level, etc The clothing patternchanges with the age of person due to the psychological and physiologicalchanges with time A child needs different type of clothing than an agedperson Similarly the clothing need also changes with the physical health

of a person Someone with specific problem with a particular fibre, likeallergy, irritation, would like to avoid wearing that particular clothing madewith these fibres Clothing selection also depends on the physical built ofbody, i.e whether fat or thin, tall or short, etc Person with special physicalneed may require specific clothing Physiological response of body varieswidely from person to person and so does the clothing need In a givenenvironmental condition a particular person may feel more cold or heat orsweat than others This is due to the fact that the thermo-physiologicalresponses are different for different persons The selection of clothingalso depends on the level of activity of a person Under heavy activity thehuman body generates more heat and sweat The clothing, he wears, should

be able to dissipate and transmit the heat and sweat quickly to keep thebody heat under control A sports person needs special sportsweardepending on the type of sports or a worker needs specific work weardepending on his activity People in challenging activities and sports could

use smart clothing, that is, clothing that can sense the wearer’s condition

or situation and, in turn, modify its own structure to protect him or her, forexample to keep the body warm or cool

A very well-known proverb says that “There is no such thing as bad

weather, only bad clothing” Textiles always have played important roles

in well-being of a human being by protecting it from different adverseenvironmental conditions and making him feel comfortable Comfortcharacteristic is an important functionality of clothing Human thermo-physiological comfort is associated with the thermal balance of humanbody, which is highly dependent on metabolism rate, physical activities,ambient temperature, and thermal and moisture transmission behaviour

of the worn clothing [2] Clothing creates a microclimate between theskin and the environment, which supports the body’s thermoregulatorysystem to keep its temperature within a safe range, even when theexternal environment temperature and humidity changes to quite anextent

Comfort is one of the most important aspects of clothing Many attemptshave been made to define comfort, but a satisfactory definition is yet to beobtained [3] Comfort has been defined by many researchers in differentways [4–6]

● Comfort is influenced by the physiological reaction of the wearer

● Comfort is temperature regulation of the body

● Comfort is the absence of unpleasantness or discomfort

● Comfort is a state of pleasant psychological, physiological andphysical harmony between a human being and the environment Allthree aspects are equally important, since people feel uncomfortable

if any one of them is absent

So, to know about the comfort characteristics of any particular fabric

or clothing, it is required to determine the different properties of the fabricwhich have direct effects on the comfort

Broadly there are four basic elements of clothing comfort, namelythermo-physiological aspect, sensorial or tactile aspect, physiologicalaspect and fitting comfort The thermo-physiological comfort concernsabout the heat and moisture transmission characteristics through clothing,i.e transmission of heat, air, and moisture (liquid and vapour) The sensorial

or tactile comfort is related with the mechanical contact of the fabric withskin, i.e how a fabric or garment feels when it is worn next to the skin.These are fabric handle or feel, softness, fullness, warm–cool touch, staticcharge generation, flexing, pricking, itching, etc The physiological comfort

depends on the aesthetic properties of fabric, i.e drape, luster, colour,crease, pilling, staining, etc The fitting comfort deals with the size and fit

of clothing

All the above comfort aspects are strongly correlated between them Inclothing comfort, the most important factor is the movement of heat andmoisture (liquid and vapour) through clothing to maintain the thermalequilibrium between human body and the environment

According to Goldman [7] there are four primary factors in clothingcomfort, i.e function, feel, fit and fashion The function related to clothingcomfort parameters are thermal and moisture (liquid and vapour)transmission, water absorbency, drying behaviour, etc The thermaltransmission is a linear function of fabric thickness and relativelyindependent of fibre characteristics Thus the thermal transmission can becontrolled by the modification of yarn and fabric structures Moisturevapour permeability also controls thermal characteristics by evaporativecooling phenomenon The water transmission in liquid form, i.e wicking,depends mainly on the type of fibre, weave structure of fabric and thefinishes applied to the fabrics The absorbency of water depends on fibretype, finishes, weave and design of fabric Although the wicking isimportant, the amount of liquid that can be blotted away from the skin isalso very important The drying behaviour depends on the type of fibre,fabric and design of fabric It is important because the ability of the bodyheat to rapidly dry clothing and restore insulation is a critical factor forsurvival

The clothing comfort related to feel are broadly divided into two distinctareas, namely the feel of clothing when held between the thumb and thefingers and the feel of clothing by the wearer when worn in contact withskin Fit may incorporate factors from fashion, including concepts thatmay be diametrically opposed to comfort [7] The clothing fashion is relatedwith the psychological comfort

Comfort and satisfaction with clothing are influenced by bothcharacteristics of clothing as well as by attitudinal and psychologicalperceptions of the wearer The clothing characteristics include thephysical characteristics of the fibres and materials from which theclothing is made, its tactile characteristics, design features of the clothing,brand labels, information on fabric/garment care, price, etc [8] Thewearer’s attitudes towards clothing are influenced by the sensoryattributes of the clothing (softness/harshness, warm/cool touch etc.),

serviceability characteristic (e.g., durability, creasing, pilling) and most

importantly by its expected comfort and satisfaction related attributes

These attitudes may be gathered either through prior experiences withthe exactly same or similar type of clothing, or from information obtainedabout the clothing through interpersonal, advertising or retail channels.These attitudes toward either fabrics or items of clothing can significantlyaffect the actual physiological comfort and other performance properties

of the clothing and can become the primary determinant of consumerbehaviour through their influence on behavioural intentions [9–11] Alarge number of studies have been reported on attitudes toward clothing[12–15]

DeLong et al [12] in their study to evaluate the consumer response toapparels asked consumers to complete the sentence “When I think aboutsweaters, I think about” without presenting any fabric samples or items

of clothing They performed a content analysis of the words thatconsumers used in order to assess the factors underlying the concept of

“sweater” Byrne et al [13], in their perception study on fibre types and

end use, used semantic differential grids to study consumer attitudestoward silk, cotton, polyester and nylon for use in sport shirts andundershirts They have concluded that the consumer attitudes towardthe names of different fabrics were distinct and that the intended end-use greatly influenced perceptions of the adequacy of the fabric Duringthe study on consumer preferences for natural, synthetic and blendedfibres, Forsythe and Thomas [14] observed that consumers have well-defined attitudes toward fibres and, with the exception of polyester/cottonblends, these attitudes are consistent across demographic variables Theattitudes of consumer about fabrics and clothing can be reliably assessedwith appropriate psychometric techniques applied to fabric or clothingnames

Conjoint analysis technique is widely used by researcher for assessingconsumer attitudes toward clothing This technique deals with the factorsrelated to the consumer attitudes and behavioural intentions by using multi-attribute choice alternatives within a specified experimental design [8,

15, 16] Using this technique, a survey had been conducted whereconsumers are given a large set of multi-attribute choice alternatives.Consumers choose or rate each combination of product variables onattitudinal or behavioural dimensions of interest The product attributesare the dependent variable and by varying the attributes and their levelsaccording to a statistically determined experimental design, conjointanalysis enables the researcher to “work backwards” from the choices/ratings to uncover the relative importance of each factor to the consumer’sdecision process Conjoint analysis has been used in clothing research tostudy the relative importance of attributes related to the aestheticperceptions of garments [17]

1.4 Human–clothing interactions

1.4.1 Clothing as thermal barrier

Hindrance to the release of body heat

Fourt and Hollies [18] have described the clothing system as “a physiological system interacting with the body” This means therelationship between human body and clothing is a two-way process Boththe clothing and the wearer perform their specific activities for others.The clothing protects the wearer from the environmental hazards for which

quasi-it has been designed, whether they are heat, cold, fire, toxic agents or anyother thing At the same time the clothing does some adverse things to thewearer, e.g by unwanted thermal insulation when it is not required, or byhindering the free evaporation of sweat from skin Presence of clothinglayer(s) prevents the efficient evaporative cooling of human body, which

is his sole defence against severe heat Thus the wearer faces the unbearableand dangerous conditions when he or she works near fire, like overheating,dehydration, and sometime may also collapses

In normal conditions, without any activity, the metabolic heat produced

by a normal person is nearly about 80 watts (same as an electric lightbulb!) and in the condition of high activity it can rapidly rise to more than

a kilowatt [19] So, the human body requires an effective cooling system,and physiological system of the body provides this cooling effect Thismetabolic heat load, mainly during high activity, poses a consistent threat

of overheating and the presence of clothing makes the threat even worse.During high activity in extremely hot environment, e.g worker in furnace,firefighter, etc gains hundreds of watts more from the surroundings inaddition to the metabolic heat generation Sweating, which is an excellentmechanism for cooling the skin by evaporating water from it, is the onlymechanism to reduce these great heat loads On the other hand, theexcessive sweating may also results dehydration During high activitycondition, in hot environment, a normal person can release sweat at therate of about 1 litre/hour There are various linked mechanisms within thehuman–clothing system which are essential to maintain the correct bodytemperature and the failure of this link of heat transfer in any form causesincrease in body temperature and the person may feel sick or dizzy Themost important mechanisms for effective heat transmission are:

● all the metabolic heat produced should be carried to the inner bodysurface (inner layer of skin) by the effective circulation of sweat;

● the skin should be able to generate the necessary amount of sweat;

● the generated sweat should get transmitted effectively (in liquid aswell as in vapour form) through clothing ensemble

One cannot adjust or change the first two mechanisms, but can definitelycontrol the third mechanism by proper clothing When someone wearsexcess number of clothing than what is required, he may feel overstressed

or overheated with normal activity

Helps to retain body heat

Except very hot environmental conditions and at very high activity levels,most of the environmental temperatures are below the human bodytemperature and clothing is required to hinder the flow of body heat tothe atmosphere So, in all these environmental conditions the heat flowsout from the human body to the atmosphere due to the temperaturedifference, i.e human body temperature is higher than the environment

In normal room temperature, i.e approximately 27±2°C, the wearerrequires minimum clothing layers to maintain the heat balance Thewearer does not require too much thermal insulation in clothing as thetemperature difference between skin and the normal environment is low.The heat, generated in the body, gets transmitted slowly through theclothing and the open body surfaces (hands, arms, face, palms, etc.) Asthe temperature of the atmosphere drops further (say below 10°C) therate of heat loss from body to atmosphere increases rapidly and the wearerfeels cold due to thermal imbalance The best and easiest way to preventthis body heat loss is to have certain insulating layer around the body,and that is done by wearing some additional layers of clothing (whichalso provide insulating still air layer) Under this condition, loss of bodyheat through clothing drops significantly and little amount of heat lossstill takes place through some opening of body surface In extreme coldconditions (say below –20°C) the loss of body heat is prevented byenhancing the thermal insulation of clothing and covering all the bodyparts

release

The symptoms of overheating or overstress due to excess number ofclothing rapidly disappear when the excess clothing is removed Thetransmission of body heat through clothing ensemble changes automatically

by different mechanisms Activity of the wearer influences the heattransmission characteristics of clothing As soon as the wearer starts moving

or walking or running the thermal insulation of clothing reduces because

of a combination of forced air circulation between and through the layers

of clothing This reduction in thermal transmission is further enhanced bythe typical bellows effect at various openings and also due to movement

the thermal insulation of the surrounding air reduces During activity theclothing gets wet from sweat which also causes the drop in the thermalinsulation This automatic reduction in thermal insulation of clothing duringactivity level may not be always sufficient and in those cases the wearerbecomes over-heated and sweats This is due to the fact that the clothinglayers actually hinder evaporation of sweat Majority of the generated sweatwets the clothing in normal environment or in cold environment condenses

in the outer layers In either case the sweat removes less heat from thebody than it does when it is able to evaporate from the skin, and additionalsweat therefore has to be secreted to maintain the heat balance.Consequently the wearer is too hot while he is active, and when he laterrests he becomes chilled because of the reduced insulation of wet clothingand the continuing evaporation of water from it [19] The over-heating ofbody can also be reduced by proper clothing design, i.e by providingeffective ventilation in the clothing The changes in clothing design may

be effected by:

(i) creating openings, to allow natural convection by chimney effect, atvarious places in the clothing, e.g neck, wrists, ankle and waist.(ii) designing loose fit clothing to have free convection of air and freeinterchange with outside air by means of a bellows effect

(iii) providing full-length zippers in the clothing for specific applications.(iv) avoiding the use of impermeable materials, whenever possible, canfurther facilitate evaporative cooling

1.4.3 Multilayer clothing system

Most of the performance clothing assemblies are generally not a singlelayer system These generally consist of a number of layers and each layerperforms its specific function These layers are generally of three types,i.e inner layer, middle layer(s) and outer layer A clothing ensemble thatshould function with high requirements to comfort and protection must beput together methodically from the inside out [20] Figure 1.2 shows thetypical functions of individual layers of a three layer clothing system, wherethe inner layer is generally an underwear which performs mainly the sweatabsorption, direct cooling of the skin, transmission and tactile functions;the middle layers are generally shirt or sweater which helps still-airentrapment to provide insulation, transmission etc.; and the outer isprimarily a shell layer for protection from extreme environmental factors,like rain, wind, chemical, heat, radiation, etc

1.5 Understanding clothing comfort

The basic and universal need of consumers in clothing is comfort and theylook for good feel and comfort when they buy clothing and other textilematerials Clothing is very important in our life that we use everyday toobtain physiological and psychological comfort and also to ensure physicalconditions around our body suitable for survival Therefore, it is extremelyimportant for the survival of human beings and improvement of the quality

of our life to have good understanding of the fundamentals of clothingcomfort From the viewpoint of the manufacturers of clothing and textilematerials, understanding of clothing comfort has substantial financialimplications in the effort to satisfy the needs and wants of consumers inorder to obtain sustainable competitive advantages in modern consumermarkets Consumer always expects some additional functional qualitiesfrom the clothes they purchase Clothing is manufactured in a wide range

of thermal, tactile and physical properties to meet consumer needs.Depending on the needs and expectations of the consumers, the clothingand textile manufacturers provide wide range of options to enhance humancomfort For example, clothing made from blends and natural fibres arepreferred to man-made fibres for all comfort attributes except smoothness,

or woven fabrics are preferred to knits for smoothness, thickness andopenness To understand the basics of clothing comfort, sensory tools aswell as the equipments to evaluate the comfort related characteristics oftextile materials have been developed Large number of studies has beencarried out and many equipment are developed in the textile and clothingarea such as mechanical, thermal and surface testing, so as to evaluate therelated physical properties, but the links between measurement and theconsumer feeling of comfort are still difficult to establish

1.2 Three-layer clothing system [21].

Thermal protection

Water repellency

Wind proof Outer layer Middle layer Inner layer Heat or Sweat (liquid or vapour)

Consumers want everything from the clothing, i.e it should look good,feel good, perform well, would like their clothing to match with their chosenattitudes, roles and images Consumers are now allowing touch, smell,intuition, and emotion to influence their decision on clothing selectionmore than their aesthetic sense As a result, great importance is beingattributed to the wearing experience and thus comfort is being reinforced

as a key parameter in clothing It is also true that requirements of consumers

on comfort changes with products and situations Clearly, understandingand satisfying the needs of consumer towards clothing products are crucialfor the long-term survival and growth of clothing and textile demand.Understanding and enhancement of clothing comfort is definitely one ofthe important issues

1.5.2 Scientific approaches

To have proper understanding of the clothing comfort and to predict comfortperformance of clothing during wear, one needs integrated scientificknowledge of physics, physiology, neurophysiology, and psychology ofcomfort In long-term perspective, it is very important to have properknowledge on clothing comfort to improve the quality of life and the survival

of human beings The clothing and textile industries should take necessaryinitiative in this area to achieve market leadership Researchers identifiedthe psychological sensory attributes what consumer desire, which iscorrelated with the technical parameters of clothing through psychophysicalperceptual trials The clothing can be developed with specified technicalparameters to achieve certain level of psychophysical comfort Li [22]reported that there are five levels of understanding clothing comfort Theimportant steps for scientific understanding of clothing comfort are marketresearch, wear trials, objective evaluation of clothing characteristics andobjective evaluation of fabric characteristics The market research is generallycarried out by identification of target group, personal interviews andconsumer surveys to gather market information on the products The weartrials can be conducted either in the field in which the clothing are used or

in climatic chambers for psychological sensory study, consumer focus groupstudy and subjective evaluation of clothing The objective evaluation ofclothing characteristics, e.g thermal and moisture transmission are generallydone either on human subjects or thermal manikins The objective evaluation

of fabric characteristics are carried out by testing transmission (moisture,heat), handle, tactile and aesthetic characteristics of fabrics The information

on clothing comfort requirements should flow from customer to technicalspecifications of fabrics and clothing to have a new product that can satisfythe requirements of consumers On the other hand, one can predict theconsumer acceptability of particular clothing by proper understanding of

fabric and clothing characteristics, physical and psychophysical mechanisms.Using statistical and mathematical tools one can easily optimize the clothingparameters as per the identified consumer’s requirements even before actualproduction.

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Psychology and comfort

comfort

The physiological factors of human body for expressing the human comfortare average skin temperature, degree of skin wetness (indicated by electricalconductivity at the body surface), rate of sweating, the amount of sweat,sweat absorbed by clothing, and rate of heart beat It is important tocorrelate all the physiological parameters with contributing psychologicalfactors to predict the perceptions of comfort Thermal effects contributeextensively to the ‘comfort’ of an individual, complex physiological andpsychological factors collectively play an important role in defining thiscomplex quality with reference to clothing [1] In fact, clothing comfort isthe psychological feeling of wearer who wears the clothing under differentenvironmental conditions The factors influencing the clothing comfortsensations of wearer can be divided broadly into three groups: (i) physicalfactors (deals with the human–clothing–environment system); (ii) psycho-physiological factors of the wearer; and (iii) psychological filters of thebrain The comfort status of wearer depends on all these factors and theircomplex interactions and synchronizations

Figure 2.1 shows the interrelationships between the important physicaland physiological factors those control the clothing comfort The figureillustrates the process of how the subjective perception of overall comfort

is formulated The physical processes provide different signals or stimuli(e.g., warm/cool, touch, prick, pressure, wetness, etc.) to the sensory organs

of the human body The human body receives all these stimuli andsubsequently generates neurophysiologic impulses The neurophysiologicimpulses are then send to the brain to take corrective actions to adjust thesweating rate, blood flow, and sometimes heat production, shivering, etc.[2] The brain, after receiving the sensory impulses, processes all theseimpulses to generate the human subjective perception of various individualsensations, and further evaluate and weigh them based on the pastexperiences The processes of evaluation and weighing are influenced by

many factors such as physical, environmental, social, cultural, etc Theclothing comfort is a human psychological perception related with clothingensemble, which is an outcome of complex linkages between individualsensory stimuli received by brain, evaluation and weighing of all thesestimuli to formulate subjective perception of overall comfort based onwear experience.

Appearance

& feel

Fitness Environmental

condition (hot / cold, RH %)

Skin sensory responses

Thermoregulatory

response of body

Heat, liquid/vapour transmission of clothing

2.1 Important physical and physiological factors controlling the clothing comfort.

2.1.1 Psychological perceptions of clothing comfort

The wearers consider the comfort as one of the most important attributes

in their clothing ensembles, so there is a need to develop an in-depthscientific understanding of the psychological perception of clothingcomfort sensations The physical comfort is greatly influenced by tactileand thermal sensations arising from contact between skin and the immediateenvironment [3] Comfort may be defined as pleasant state of physiological,psychological and physical harmony between a human being and theenvironment [4] Comfort can also be defined as a holistic concept, which

is a state of multiple interactions of physical, physiological, andpsychological factors [5] All these definitions only identify the factorsinfluencing the human psychological perceptions Wong et al [6] developed

a linear model based on artificial neural network predictions using threemajor factors which affect the comfort perceptions, namely moisture relatedfactor, tactile sensations and thermal-fit comfort, and their relative weights

to predict overall comfort perceptions They have developed feed-forwardback-propagation neural network models to predict an overall comfortperception from ten individual sensory perceptions (clammy, clingy, damp,sticky, heavy, prickly, scratchy, fit, breathable and thermal) They havereported a good agreement between predicted and actual clothing comfortperceptions, which indicated that the neural network is an effectivetechnique for modelling the psychological perceptions of clothing sensorycomfort They have further reported that the functions and interrelationships

of individual sensory perceptions and comfort are unknown

2.1.2 Sensory perceptions of clothing comfort

Different types of sensations generated from clothing ensemble dependmainly on the various combinations of type of clothing, type and level ofactivities and the environmental conditions experienced by the wearerduring the activities The most common clothing comfort related sensoryattributes are thermal, moisture, tactile, hand, and aesthetic experiences.The experts in the field of sensory attributes can easily identify thedifference between the above attributes and suggest accordingly But, it isvery important to identify some commonly recognized comfort attributes

of clothing among ordinary wearers, and what they are if they exist Whenthe level of human activity or the temperature and humidity of microclimatechange the changes in various sensory perceptions, like warmth, chilliness,scratchiness, dampness etc., can be very easily detected [7] Strongsensations can also be experienced, both indoors and outdoors, when mild

or heavy sweating occurred, and during modest excursions of warming orchilling following the inception of sweating There are many attributeswhich describe the clothing comfort sensory perceptions of human Some

of the important attributes are loose or tight, heavy or light, stiff or pliable,sticky or non-sticky, absorbent or non- absorbent, cold or warm, pleasant

or clammy, dry or damp, pricky or non-pricky, rough or smooth and scratchy

or non-scratchy, etc Some of these attributes do not give useful contribution

in prediction of clothing comforts So, most important and establishedattributes for subjective evaluation of sensory perceptions of clothingcomfort are course–fine, rough–smooth, stiff–pliable, harsh–soft, cool–warm, hard–soft, and rustle–quiet, for expressing sensorial comfort Indeveloping methodology for evaluation of fabric handle, Kawabata [8]generated sensory attributes by letting a panel of expert judges (the HandEvaluation and Standardization Committee) judge the fabric handle andasking them the reasons for their decisions They identified terms such asKOSHI (stiffness), NUMERI (smoothness), and SHARI (crispness) as

‘primary hand’ expressions

The investigation on physiological sensory responses to clothing, ofconsumers living in different countries, revealed that the ratings of most

of the sensory attributes are significantly different between three types ofclothing, i.e summer wear, winter wear, and sportswear No significantdifferences in rating of the sensory descriptors were found between maleand female respondents The physiological sensory responses to clothingwhich were considered in the study are snug, loose, stiff, lightweight,staticky, non-absorbent, sticky, heavy, cold, damp, clammy, clingy, rough,cool, hot, soft, warm, wet, prickly, itchy, chill, sultry, tickling, and raggy[2] The wearers themselves know best and they are capable of makingobjective, quantitative and repeatable assessments of their sensations oftheir clothing Therefore, sensory attributes should come from the wearersinstead of experts or researchers

Fechner, in 1860, originated psychophysics to describe the mathematicalrelationship between the conscious experience of a sensation and anexternal physical attributes [9] According to his theory, if one knows themathematical form of the psychophysical relation between a physicalattribute and its corresponding sensation, he can measure psychologicalattributes by measuring their physical factors Therefore, psychophysics

is about the quantification of the strength of internal sensations, whichcan be broadly defined as the quantification of sensory experience Thestrength of internal sensations has two aspects of indication, i.e (i) theassessment of human powers of signal identification and sensorydiscrimination, and (ii) the calibration of subjectively perceived intensitiesand other parameters of stimulation

Weber, in 1834, [10] proposed that the threshold (i.e the just noticeabledifference) of stimulus (ΔS p) are proportional to the magnitude of stimulus

S p This is known as Weber’s law and can be expressed as:

where K is a constant indicating the power of a human being to detect

signals and discriminate sensations This law holds good for many stimulusattributes down to about the absolute threshold which is the smallestmagnitude of stimulus that can be perceived

Fechner, in 1860, [9, 10] proposed using “just noticeable deference” as

a unit to measure internal sensation Fechner assumed that sensation R s increases as the logarithm of physical stimulus magnitude S p; this is calledFechner’s law and can be described as:

R s = K´logS p (2.2)

where K´ is the constant determined by the stimulus threshold which

represents the lowest physical value evoking sensation and the deferentialthreshold providing a subjective unit of sensory intensity This law statesthat sensation increases in arithmetic steps as the physical stimulus isincreased in logarithmic steps Both Fechner’s law and Weber’s law ofpsychophysics are related to each other

Stevens, in 1953, [10] developed a method of estimation of therelationship between subjectively perceived intensity and physical stimulusstrength This method was applied to a large number of different stimulusattributes The results from each stimulus attribute generally follow thefollowing relationship,

where, ‘a’ is a scale factor and ‘b’ an exponent characteristics of the

attribute This equation is known as Stevens’ power law

All these laws of psychophysics indicate that there are fundamentaldifferences between the physical stimulus and the sensation that oneexperiences Weber’s law and Fechner’s law play some fundamental role

in sensory discrimination in terms of the ability to distinguish one stimulusfrom another, but fail to provide a basis for measuring sensation Stevens’law proposes a power relation between physical stimulus magnitude andinternal sensation which provides a ‘direct’ measurement of sensation insensory judgment process

Psychological scaling is a process of assigning numbers to characteristics

of objects or events, according to rules which reflects some aspects ofreality Psychological scaling has been widely used in marketing research

to obtain consumers opinions and study their attitudes and preferences.Assigning numbers does not always correspond to the real numbers thatare obtained from objective measurement in physical means The numberscannot necessarily be added, subtracted, divided or multiplied The numbersare used as a symbol to represent certain characteristics and the rulesspecifying how numbers are assigned to the characteristics to measure.These rules may be arbitrary and changes as per the specific condition.The rules governing how to assign numbers constitute the essentialcriteria defining each scale There are four types of scale of measurement:nominal scale, ordinal scale, interval scale and ratio scale [11] Movingfrom nominal scale to ratio scales, the rules become more complex andthe kinds of arithmetic operations for which the numbers can be used are

increased Each scale exhibits symmetries and hence corresponds to a type

of symmetry group [12] In fact, the four scales correspond to a descendingsequence of subgroups, e.g the group for the nominal scale containingthe group for the next scale, i.e the ordinal scale Similarly, the group forthe ordinal scale contains the group for the interval scale, and the groupfor the interval scale contains the group for the ratio scale In other words,the symmetries which are members of the set corresponding to the ratioscale are also members of the set corresponding to the interval scalealthough the latter contains additional symmetries as well, and so on, theset corresponding to the nominal scale having the greatest number ofsymmetries as members [13]

Nominal scales consist of numbers used to categorize objects A nominalnumber serves as a label for a class category In a nominal scale, items aresorted into classes with no quantitative information conveyed Numbersmay be used in a nominal scale, but they are only used to indicate groupmembership, e.g., the numbers on the jersey of a player in a hockey team

or one can assign 0 to male and 1 to female The number 1 does not implysuperior position to number 0 or number on the jersey of a player generallydoes not indicate the performance of player The rules for nominal scalesare that all numbers of a class have the equal value The only arithmeticoperation that can be performed on nominal data is the count in eachcategory Nominal numbers cannot be added, subtracted, multiplied anddivided The nominal scales only distinguish the objects or events on thescale from things that are not on it Due to its high degree of symmetry, itconveys little information and is hence the weakest form of measurement.For example, grading the students only in the form of pass or fail does notconvey much information about student performance than assigning grades

or exact percentile

Ordinal scales comprise numbers or other symbols used to rank theevents or objects according to their characteristics and their relative position

in the characteristics Ordinal data indicate the relative position of objects

on certain characteristics scales but not the magnitude of the differencesbetween the objects A mode or median may be used, but not a mean Non-parametric statistics can be applied to ordinal data Some of the symmetries

in nominal scales disappear during the shifting of events or objects fromnominal to ordinal scales This is because the ordinal scale is lesssymmetrical than a nominal scale For example, generally the top person

in an organization gets highest salary and the salary reduces according tothe hierarchy in the organization But as long as the hierarchy is preserved,there is no social significance in varying the salary in each level Hence,there are symmetries here as well, transformations which would make nosocial difference But there is less symmetry here than in nominal scales,

since some transformations that would not socially matter in ordinal scales

do matter in nominal For example, giving more salary to manager thanthe president would be forbidden, or it would indicate a change in status.The transition from ordinal scale to interval scale results in a reduction

of symmetries In the interval scales the numbers are used to rank theobjects or events in such a way that numerically equal distances on theinterval scale represent equal distances in the characteristics of the objects

or event being measured But both zero and their unit of measurementare not fixed and are arbitrary Therefore, interval data can indicate bothrelative position of objects and the magnitudes of differences betweenthe objects on the characteristics being measured The entire range ofstatistics can be applied to interval scales On an interval scale, one unitrepresents the same magnitude as any other For example, in Box andBehnken [14] three-factors and three-level model the factors (independentvariables) are coded with –1, 0 and +1 for their three levels In the actualdata the intervals in the factors are numerically same Another example

is the measurement of temperature in centigrade scale One degreecentigrade is warmer than 0°C to the same extent as 2°C is warmer than1°C Fiske [11] stated that “Equality matching relationships resemble aninterval scale in that people can not only specify who owes what to whom,but also how much they owe” On the basis of ordinal scale, people keeptrack of imbalances or differences between each other and try to maintainbalance Equality, following particular turn, strict reciprocity ismaintained strictly Examples are voting, games that involve equal turn-taking, and so on There is less symmetry here than in the case of ordinalscale In interval scale, one must make sure that everyone has the samething, however, sameness is defined This degree of precision is lacking

in ordinal scale [13]

A ratio scale is exactly like an interval scale, except that it has an absolute

0 point For example, the kelvin temperature scale has absolute zero pointbut the centigrade temperature scale measures the freezing point of waterdefined as zero degrees Celsius and does not have absolute zero scale.Ratio scales represent the numbers used to rank objects such thatnumerically equal distances on the scale represent equal distances of thecharacteristics measured and have a meaningful zero Like interval scales,entire range of statistics can be applied to ratio data Ten degrees centigrade

is not twice as hot as 5°C, but 10 K is twice as hot as 5 K In ratio scale,people order their interactions according to a system of ratios andproportions such as salary, rents, taxes, etc This allows each individual orgroup of like-minded people to decide how to act and evaluate actionsaccording to cost-benefit analysis [13]

All the above four types of psychological scales are important for betterunderstanding of psychology of clothing comfort The nominal scales

determine quality and have been used for categorization and classificationsuch as gender, age, and place of living Ordinal scales determine equalityand relative position and have been used to obtain the rankings of fabrics

or clothing in consideration The most frequently used scales are the intervalscales, which determine equality, relative position, magnitude ofdifferences and have been widely used to obtain the perception of variousattributes of clothing The ratio scales are mainly applicable to the datagenerated from physical instruments, which determine equality, relativeposition and magnitude of difference with a meaningful zero

2.2.3 Psychophysical scaling of clothing comfort

The tactile parameters, like prickliness, fabric itchiness, fabric stiffness,fabric softness, fabric smoothness, roughness, scratchiness, etc., arebasically sensory comfort attributes, but the psychological comfort is not

a sensory attribute, because it is not associated directly with any singlehuman sense organ The psychological clothing comfort is characterized

by emotion and affection, which is related with the liking towards particularclothing Thus, there is no underlying physical dimension of the stimulusthat varies continuously and is monotonic with the perception of comfort.The same stimulus can generate altogether different comfort responsesfrom different individuals As a result, it is not possible to define a comfortscale based on physical standards that is valid for all users [15] In generalthe clothing comfort is characterized by emotional attributes, so thejudgment can be done effectively by untrained consumers instead of

experts This requires a method for psychophysical scaling of clothing

comfort that is simple and easy to understand which do not require anytraining or complex instructions The ‘category scale’ is the most commonlyused subjective scale for rating comfort This is characterized by a series

of verbally and/or number labelled points or descriptive categories, like

‘extremely comfortable’, ‘moderately comfortable’, ‘slightly comfortable’,etc In this type of scaling, a person can rate his subjective comfortsensations by placing them into one of several descriptive categories Sinceless than five categories can result in a loss of discrimination sensitivity,the number of categories is typically around seven to nine, or sometime itcan also be more [16, 17] Due to the simplicity, versatility, and highreliability the ‘category scales’ are widely used for measurement ofsubjective clothing comfort and other psychological attributes

Although there are many advantages, still there exist some criticalproblems associated with the use of ‘category scales’ In case of anumbered category scale, the numbers with equal intervals do not representequal subjective intervals [18] In the labelled category scales, subjectsattend primarily to the word labels and not to the numbers [19] In these

cases, unless the verbal labels are chosen on the basis of extensiveevaluation process to verify that the differences between ‘slightlycomfortable’ and ‘moderately comfortable’ are the same as those between

‘moderately comfortable’ and ‘extremely comfortable’ the scale cannot

be considered to be an interval scale, but merely an order of comfortsensation Another common problem with category scales is that thenormal tendency of a person is to avoid the end categories; this is called

“category end effect” This “category end effect” results in seven-pointcategory scales being functionally reduced to five-point scales aftereliminating two end points; and similarly the five-point scales is reduced

to three-point scales, and so on

The recent developments in psychophysical methodology that enablebetter quantification of both the descriptive aspects of tactile sensationsand the scaling of the emotional attributes of handle helped the researchers

in applying well-established psychophysical approaches to study thesensory and comfort characteristics of clothing After the development ofKawabata instrumental evaluation systems [8, 20, 21] for measuring low-stress mechanical characteristics of fabrics, it has now become relativelysimple to measure many subjective attributes objectively Combining thepsychophysical sensory methodology with the established instrumentalmethods of fabric characterization now makes it possible to develop betterpredictive relationships among sensory, instrumental and comfortcharacteristics of clothing

Human being often uses hands to obtain tactile information, but much ofthe tactile sensations come from parts of the body other than hands Thissuggests the necessity of study of the perception of clothing comfort inactual wear situations Therefore the wear trialing is an important techniquefor clothing comfort research Sensory clothing comfort perceptions areprimarily associated with skin sensory systems In addition to this theclothing comfort sensations involve various sensory channels from all thefive senses: visual, auditory, smell, taste and touch A certain type ofclothing comfort sensation is generated under certain wear conditions with

a particular type of external stimuli and physical activity The externalstimuli (heat, moisture, wind, etc.) and mechanical stimulation from fabric

to the skin (softness, scratchy, pricky, etc.) are normally generated underspecific combinations of physiological states (e.g sweating rate), materialsused in the clothing, fitness of clothing and environmental conditions (e.g.,temperature, humidity and air velocity)

Hollies et al [22, 23, 25] proposed the wear trial technique to generatereactions of wearer to any perceived discomfort sensations produced by

different climatic conditions, and by alternating sweating and cooling offconditions that might be encountered in actual wear of clothing In thewear trial experimental technique they also characterized the sensorycomfort of clothing, which included a number of components:

(i) Generation of sensory attributes with wearers

(ii) Selection of particular testing conditions for effective analysis ofthe perception of various sensations

(iii) Designing attitude scales in the way of subjective rating sheets toobtain various sensory responses to particular garments The sheetscontain different comfort attributes (e.g., stiff, sticky, non-absorbent,cold, damp, clammy, clingy, rough, scratchy, etc.) at different timeinterval in particular environmental condition The comfort intensitywas scaled at five different scales, i.e 1 is totally uncomfortable and

(vi) All collected data were analyzed and the results were interpreted

In a recent research study [24] warm and humid climatic conditionswere produced using a climatic chamber with precise control of airtemperature and humidity In this study, different varieties of garmentswere worn with six coverall types Each test session was made up of fiveindividual evaluation periods, which yielded approximately 900 individualevaluations Comfort ratings were assessed on all test garments in each ofthe five rating periods of the protocol An evaluation form was designed

to record ratings of comfort and sensory properties for each of the fiveperiods The scales used to assess overall comfort, thermal sensation, andcontact comfort sensations were recorded During each evaluation period,wearers were asked to indicate the number, on the designated rating scale,that best described their perceived sensations The wearers and the garmentswere precisely weighed before and after completion of the wear trialprotocol to estimate the moisture loss from the body, and to determine theamount of moisture accumulated in the test garments During the weartrial study the overall comfort sensations, thermal sensation and skincontact comfort sensations of garments were rated by the wearers withdifferent terms and scales The overall comfort sensations were expressed

in seven scales, i.e 1 – Very uncomfortable, 2 – Uncomfortable, 3 – Slightlyuncomfortable, 4 – Neither comfortable nor uncomfortable, 5 – Slightlycomfortable, 6 – Comfortable and 7 – Very comfortable Statisticaltechniques have been adopted for data analysis

Wong et al [26] used neural network technique in wear trial to predictthe human psychological perceptions of clothing sensory comfort They haveselected twenty-two professional athletes as subjects to take part in thepsychological sensory cycling trial The wear trials were conducted in anenvironmentally controlled laboratory Before the trial, athletes weresubjected to medical fitness examinations to ensure that they were able tocomplete the experiment They have chosen different commercial sportswear

in their study Initially they invited the professional athletes for a pre-trialbefore the formal trials to obtain training and understanding of the questionsand procedures involved During each trial, each athlete was required toshower upon arriving at the laboratory, then change into a test garment and

a pair of nylon shorts, and rest to equilibrium for 20 minutes During thewear trial the laboratory conditions were controlled at 15°C, 65% RH, and

an air velocity varying between 0.15 and 1.50 m/s At the end of theequilibrium period the athletes were asked to ride ergonomic bikes for 90minutes under work loads maintaining their heart rates at 70% of theirestimated maxima The athletes were asked to rate the sensory perceptions(e.g., clammy, clingy, sticky, damp, heavy, prickly, scratchy, fit, breathableand thermal) of the sportswear at different time interval, i.e at the beginning,after 30 minutes, after 60 minutes and after 90 minutes The ratings by theathletes were subsequently converted into 0–100 scales for all the sensoryperceptions except fit and thermal sensations The fit and thermal sensationswere rescaled to the range from –50 to +50 because in these two perceptionsthe wordings used in the scale’s two ends to describe the perception of fit(from too loose to too tight) and thermal (from too cold to too hot) weredifferent from the other sensory perceptions such as damp (from not at all

to extremely) In their study, Wong et al [26] developed the neural networkprediction model on the basis of a feed-forward back-propagation network.The network model consisted of three layers, i.e input layer, hidden layerand output layer A good agreement between predicted and actual clothingcomfort perceptions have been observed, which proved that the wear trialtechnique is an effective technique for predicting the psychologicalperceptions of clothing sensory comfort

The physical attributes of the human body is directly related to the aestheticcomfort characteristics of clothing A large number of researchers [27–32] have studied the complex interplay between clothing aesthetics andbody attributes and the human body has been designated as the centralelement in the aesthetic experience of clothing The relationships betweenthe aesthetics of clothing and the physical attributes of the body is not thematter of only textile and clothing discipline but many other fields of

research, like physical and demographic attributes affecting aesthetics,social aspect, psychological, cultural aspects that influence the aestheticexperience, etc The researchers have taken into account of all these factors

in their studies on clothing aesthetics

Human body imaging technique may be adopted in the study of clothingaesthetics The clothing not only creates a person’s appearance but alsoprovide aesthetic pleasure to the person through the wearing experience.The wearers generally try to achieve the aesthetic pleasure through theirclothing by emphasizing certain positive features of their bodies throughtheir clothing and hiding other negative features Therefore, aestheticattributes in clothing helps to minimize the differences between culturalbeauty concepts and their perceived appearance, which helps to improveself-image and have stronger self-esteem of a person [33]

2.4.1 Evaluation of clothing aesthetics

Clothing comfort related to aesthetics is a complex interrelationshipbetween the following concepts:

● Style of the clothing adopted

● Surface texture of clothing

● Drape of fabric used

● Cover

● Creasing and resilience characteristics of fabrics

All these concepts are generally described by how they are subjectivelyperceived by common word pairs used to communicate their values (e.g.,thick–thin, rough–smooth, etc.) The physical or transmissioncharacteristics of fabrics, namely mass per unit area, thickness, threaddensity, air permeability, thermal transmission, wicking, etc., can be easilymeasured by objective test methods But, due to significant subjectivitythe aesthetic characteristics cannot be measured accurately and there is nostandard method of measuring aesthetic characteristics of clothing Thefabric aesthetics is entirely subjective and different people can rate samefabric in different scales based on their own perceptions

The main problem with the measurement of aesthetic attributes ofclothing is to gather useful and consistent information by questioningpeople about the clothing or fabric If this is done properly, then thenumerical data can be obtained using different mathematical techniquesand subjective test methods The possible steps to measure the fabricaesthetics are [34] as follows:

● Definition of fabric aesthetics in terms of basic elements having theform of common words

● Identification of a system for selecting rating scales This systeminvolves questions for subjective measurement of these basicelements.

● Transformation of data from rating scales to numerical definition of

a specific aesthetic property

By the term ‘aesthetics of clothing’ we generally mean the appearanceand handle of fabrics, which are mainly perceived by the senses It hasbeen already mentioned that the perceptions are relative attributes, i.e itcan be scaled based on their relative position on scales involving contrasts(warm–cool, good–bad, soft–hard, beautiful–ugly) Clothing aestheticperceptions are the combinations and interrelations of measurable physicaldata (rigid–flexible, soft–hard) and values, which are psychological factors(good–bad, beautiful–ugly, fashionable–unfashionable) Someterminologies associated with the aesthetics of clothing are reallyconceptual, for example hand, cover and body do not have value polarity,i.e they need not be good or bad, desirable or undesirable Moreover, allthese terminologies do not have a simple measurable physical reality.However, sometimes these parameters are defined to represent sense dataonly For example, ‘surface texture’ is a fabric parameter which can bemeasured subjectively, but still this is merely a terminology whichrepresents the skin sensorial as well as visual sensations of fabric Limitingthe meaning in this way often restricts communicative value The surfacetexture of fabrics is evaluated in relation to the aesthetic comfortcharacteristics of clothing To evaluate is to judge something on a scalethat has opposite poles or a gradation For example, a scale for evaluatingcomfort concepts is the pain–pleasure polar scale It is a psycho-physicalscale Aesthetic concepts are not physical attributes These can be expressed

in terms of psycho–cultural scales and can be evaluated on polar scalessuch as beautiful–ugly, good–bad, etc The surface texture of a specifictype of fabric can be evaluated by the simple polar word scale, like soft–harsh or rough–smooth It is quite possible that a fabric is aestheticallyvery beautiful, but painful from the skin sensory comfort point of view.For example, a tweed fabric may be unpleasant to the skin but pleasant tothe eye or an aesthetically beautiful winter garment may be thermo-physiologically extremely uncomfortable in warm and humid conditions.The aesthetic character of fabrics is primarily defined by subjectivemethods The wearers are asked to evaluate qualities identified by simpleword pairs whose meanings can be easily recognized as polar oppositewords, like smooth–rough, soft–hard, flexible–rigid Some of the confusingclothing terms should be avoided in evaluating the fabric aesthetics Forexample, for evaluating the drape behaviour of fabric, if one wants todecide the fact that whether the fabric is good or bad the answer will create

confusion He should know the exact application of fabric, e.g whetherthe fabric will be used for skirts or for window coverings A fabric drapemay be good for window covering, but the similar drape may not beacceptable for skirts So, simpler attributes signified by polar words, likeflexible–stiff, which are related to fabric drape characteristics, need to beevaluated.

2.4.2 Aesthetic concepts of clothing

Clothing aesthetics can be divided into different aesthetic concepts.Figure 2.2 shows the interrelationships among physical parameters,psychological attributes, subjective evaluation and aesthetic comfort ofclothing

Physiological sensations

(visual, tactile,

kinesthetic)

Objective evaluation (physical or tensile testing data)

Simplified polar scale (beautiful–ugly, good–bad)

Clothing aesthetic concepts

Subjective evaluations

expressed by words

(soft, harsh)

2.2 Components of clothing aesthetics.

Following are the guidelines for setting aesthetic concepts related topsychological clothing comfort:

● The concept must be related to at least one of three main physiologicalsensations, i.e visual sensation, tactile sensation, or kinestheticsensation

● The concept can be a combination of sub-concepts, expressed bywords which are more explicit For example, ‘resilience’ is lessexplicit than its component sub-concepts ‘compressional resilience’and ‘liveliness’ Similarly, the term cloth cover cannot communicatethe aesthetic concept completely, so its sub-concepts ‘top cover’ and

‘bottom cover’ are used

● The concepts may be made technically explicit by physicalmeasurements These measurements attempt to quantify objectively

to replace the sense data

● Aesthetic, concepts or sub-concepts can always be evaluatedsubjectively Subjective evaluation scales are represented by commonwords (quality words) which express the psychological value of thesense data associated with the concept

The most commonly used concepts related to clothing aestheticattributes are clothing cover, drape, body, style, surface texture andresilience [34]

‘bottom cover’ The ‘top cover’ is the apparentcontinuity of the surface of fabric, i.e degree ofobscurity of the fabric weave pattern due to surfacefuzziness On the other hand the ‘bottom cover’ is thedegree of obscurity of the fabric weave pattern due tofabric sub-layer The cover can be expressed by dense–open, fuzzy–clean, smooth–rough, full–lean, etc Thefabric cover is objectively measured by streak meter,light transmission, surface contact area, airpermeability, etc

‘liveliness’ and ‘fit’ The term drape means the form

a fabric will assume due to its own weight when hungfreely The aesthetic perception of fabric drapedepends on the behaviour of fabric under static anddynamic states The fabric drape is expressedclinging–flowing, dead–lively, limp–crisp, sleazy–full, etc Drape of fabric mainly depends on thebending and the shear characteristics and can besubjectively evaluated by measuring bending rigidity(cantilever or loop method), drape coefficient bydrape meter

between the edges of fabric, i.e the perception ofthe total substance of fabric during use The body offabric is expressed by light–heavy, lofty–thin, bulky–sleazy, full–lean, etc The fabric body is subjectivelyevaluated by measuring mass per unit area, thickness,porosity, density, etc

Style – Style is basically a visual aesthetic perception and

can be perceived through colour, pattern and type ofclothing Clothing style is evolved from thecombined perceptions of the textile arts andtechnology The style of fabric is subjectivelyevaluated by measuring the colour value, depth ofshade, weave structure, yarn structure, clothingpattern, fit of garment, etc

Surface texture – The surface texture of fabric means the tactility,

surface roughness and pattern of fabric This isbasically tactile and visual perceptions of fabrics It

is generally expressed by the terms smooth–rough,dry–clammy, grainy–plain, slippery–sticky, slick–greasy, fuzzy or hairy–clean, soft–hard, pricky–soft,warm–cool, dull–lustrous, etc Subjectively thesurface texture can be evaluated by measuringsurface roughness of fabric, fabric–fabric or fabric–other surface friction both static and dynamicconditions, optical reflectance of fabric surface,contact point or contact area at the fabric surface,surface fuzziness, etc

Resilience – It is the ability of a fabric to return to its previous

position after deformation force is released.Generally resilience can be of different type, i.e.resilience from wrinkle or crease, compressionalresilience, extensional resilience, liveliness, etc Theperception of wrinkle or crease resilience is theability of fabric to recover from wrinkle or crease.Similarly, compressional resilience and extensionalresilience are the perceptions of the resistance to andrecovery from transverse compression and planerextension of the fabric respectively The liveliness

is the perception of the rate of recovery from smalldeformations The resilience is generally expressed

in terms of bounce–limp, lively–rubbery, lofty–mushy, snappy–stiff, nervous–dead, etc Thesubjective evaluation of resilience characteristics offabric is done by measuring compressional, tensile

or bending characteristics of fabrics (e.g Kawabataevaluation system), vibration damping, creaserecovery angle, etc

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Neurophysiological processes in clothing comfort

The structure of human skin is very complex Figure 3.1 shows the structure

of hairy skin which covers most of the human body The skin has severallayers The overlaying outer layer is called epidermis, which consists ofseveral layers of dead cells on top of a single living cell The layer belowepidermis is called dermis, which contains a network of blood vessels,hair follicle, sweat gland and sebaceous gland Beneath the dermis aresubcutaneous fatty tissues The layers of epidermis are as follows: StratumGerminativum, i.e growing layer; Malpighion layer, i.e pigment layer;Stratum Spinosum, i.e prickly cell layer; Stratum Granulosum, i.e granularlayer; Stratum Lucidum and Stratum Corneum, i.e horny layer [1] Thebasic functions of human skin are [2]

● To protect from external stimuli like light, heat, cold and radiation;

● To check of body fluids and tissues;

● Reception of stimuli like pressure, heat, pain, etc.;

● Biochemical synthesis;

● Metabolism and disposal of biochemical wastes;

● Regulation of body temperature;

● Controlling of blood pressure;

● Prevent penetration of noxious foreign material and radiation;

● Cushions against mechanical shock;

● Interspecies identification

Skin is the interface between the body and its environment and it ishighly stimulated and contains specialized sensory receptors to sensedifferent external stimuli There are mainly three types of stimuli, i.e.mechanical interactions with external objects, thermal interactions due toheat flow to or from the body surface, and damaging (traumatic andchemical) insults In responding to these stimuli, the skin sensors generatedifferent sensations, like touch, pressure, pain, warm, cold, etc