Impact of water hardness on consumers' perception of laundry washing result in five <scp>E</scp>uropean countries

Abstract

Washing clothes, laundry and other home textiles is one of the most widespread housework in the world (Pakula and Stamminger, 2010). The washing performance depends on the following four factors, depicted by the Sinner circle, namely: chemical action, mechanical action, temperature effect and time (Sinner, 1960; AISE, 2013). If the role of one factor is reduced, the loss must be compensated for by increasing one or more of the other factors to maintain the same level of washing performance. On the other hand, water has always been the most important commodity in any type or size of laundry. Thus, water has been introduced by Stamminger (2010) as a fifth factor to show the importance of water as essential element in wet cleaning. Water comes, mainly, from two sources: surface and underground aquifers. Rainwater dissolves mineral matter as it flows over and through the ground on its way to rivers, lakes, springs and the ground water supply. The dissolved matter consists of a wide variety of minerals including calcium, magnesium and iron compounds. Calcium and magnesium ions (present as sulphates, chlorides, carbonates and bicarbonates) cause water to be hard. Water chemists measure water impurities in mmols per litre, but water hardness is also often expressed in German (°dH) or French (°fΗ) degrees. Table 1 gives common classifications for hard water with values listed in the three most common scales. The different scales can be interrelated mathematically (see Table 1). Hardness in laundry water is a problem because the minerals that cause it interfere with the cleaning action of soaps and detergents. Surfactant molecules constitute the part of the detergent mixture that does the actual cleaning work. In most laundry detergents, the main surfactant used is an anionic surfactant. These surfactants are very effective at drawing oily materials and oil/clay soil into emulsion in the wash water. However, positively charged magnesium ions (Mg+2) and calcium ions (Ca+2), which are present in hard water, tend to bind themselves to the negatively charged heads of these surfactant molecules. Surfactant molecules that have reacted with the water in this way fall out of solution, as they no longer have the electrically charged head as it was this ‘polar’ end that was keeping them dissolved. As a result, larger amounts of detergents are needed to counteract the minerals, and laundry results are not as good as when there is no hardness present. Hardness minerals also react with carbonate builders commonly found in non-phosphate detergents. The resulting product is a white precipitate, calcium and magnesium carbonate that makes fabrics stiff and harsh and leaves a film on fabrics which tends to make colours appear faded or streaked with white. No precipitate is formed when the carbonate-built detergents are used in soft water. Furthermore, in recent years, there has been renewed interest in soap, but the difference in performance in hard and soft water is more dramatic when soap is used. Soap reacts with the calcium in hard water to form sticky curds: hence, there must be more soap than is needed to react with all the calcium in the water before it can start to clean. The soap curds formed by the reaction mentioned earlier cause a problem in laundering because they cling to clothes and trap soil on fabrics. Therefore, rinse water should be softened as well as wash water to prevent soap curd formation and to eliminate chemical and detergent residue in fabrics. Very few published research data can be found on the effect of water hardness on the laundry process. Arai (1966) studied the effect of concentration and kind of detergent, and the impact of oil on soil removal efficiency in hard water. He found that there was a linear relationship between concentration of detergent and water hardness at maximum soil removal efficiency. This relationship was dependent on the nature of the oily soil and kind of detergent. In his study, Cameron (2007) showed that lime deposits on fabrics may have caused discoloration of fabrics and made them harsh and scratchy to touch, i.e. water hardness reduced the satisfaction of the consumer by the washing process. In another study in the US by the same author (Cameron, 2011), it was revealed that these mineral deposits could decrease the life of appliances and reduce the efficiency of the detergent. Also, that regarding the effect of water hardness on the action of detergents, liquid detergents performed equally well in all water conditions. Finally, it was found that powdered detergents outperformed liquid detergents in soft water (Cameron, 2011). The same author reported that more than 30% of additional detergent may have been required to allow powdered detergents to perform as effectively in hard water as they did in soft water (Cameron, 2011). Nagarajan and Paine (1984) used an experimental method to evaluate the relative water hardness control performance of different ion exchange builder types under conditions closely simulating those of detergent's end-use. Brown et al. (1991) discussed the effect of water hardness level on washing quality using commercial detergents. They determined the water hardness for 10 samples of water. They found that a wide variation of water hardness ranged from very soft to very hard. Also, they evaluated the effectiveness of six commercial laundry detergents of different formulations. The authors showed that the detergent containing a non-ionic surfactant with a phosphate builder gave the best whiteness results, regardless of water hardness. Umber et al. (1992) evaluated water hardness on washing performance of surfactants, and they used five different surfactants at 2.0% concentrations. They found that the most and least effective ones were Synthrapol N and Ahcowet RS, respectively, based on their rating of whiteness index. Also, Synthrapol N and Ahcowet RS were evaluated with the addition of sodium carbonate, sodium tripolyphosphate and a 1:1 combination of the two builders. They showed that in both cases the addition of a builder improved the cleaning efficiency of the surfactant, and that although each builder alone improved the cleaning efficiency, the combination of sodium carbonate and sodium tripolyphosphate improved efficiency at a lower total concentration. Cameron and Brown (1995) evaluated the effectiveness of 42 detergents (11 non-phosphate containing powdered, 12 phosphate containing powdered, 11 unbuilt liquid and eight built liquid), of varying formulations, in cleaning a standard soiled fabric in water of varying hardness. They demonstrated that powdered detergents were significantly affected only at very high water hardness levels. They showed that increasing water hardness had no significant effect on liquid detergents, and that powdered detergents performed better than liquid detergents in cleaning the standard soiled fabric. The literature survey revealed that the studies about the effect of hard water on washing performance in general is very limited, even though there are many published researches on the laundry habits of consumers focusing on the resource efficiency of washing (Pakula and Stamminger, 2010; Hustvedt, 2011; Laitala et al., 2011; Yamaguchi et al., 2011) and on the main washing factors such as temperature, detergent type, etc. (Rowe, 2006; Stamminger, 2011; Laitala et al., 2012; Jack, 2013; Kruschwitz et al., 2014). Furthermore, the data available in the literature do not provide satisfactory information as far as the impact of water hardness on consumer's perception of washing results is concerned. Accordingly, the present research was conducted in order to identify consumers' perception on water hardness effects in laundering in five European countries. Also, the degree of satisfaction of the consumers from the washing process was examined and correlated to the water hardness. Finally, in order to get a better understanding of the washing habits of the respondents, information such as washing temperatures per clothing item and use of washing additives (e.g. textile softener, water softener, colour catcher, machine cleaner, etc.), were also identified. Wash habits and practices vary a lot throughout the world (Pakula and Stamminger, 2010). Thus, the aim of the study was to investigate how well the consumer is aware on the effect of water hardness on household laundry and how much this is perceived by the consumers' washing result. The research was conducted using a structured questionnaire compiled by the members of the Board for Washing Excellence1 . The use of questionnaires is well documented in issues related to the identification of consumer behaviour towards household technology (Stamminger, 2011). The research took place via the Internet from 8 to 18 March 2013 in five European countries, namely Germany, France, Italy, Russia and the UK. Approximately 1000 people were conducted in each country by a professional marketing company for a total of 5053 respondents. However, before performing the statistical analysis of the results, each questionnaire was checked for consistency based on the comparison of the results of the following two questions: the first one was straightforward ‘How many loads of laundry do you do each week?’ The second question was phrased as ‘How often do you wash at the following temperatures?’ where various washing temperatures (15/20°C, 30°C, 40°C, 50°C, 60°C, 90°C) were given along with the washing frequency. The weekly frequencies of washing at each temperature were then summed up (see Table 2). The number of consistent consumers in each country is presented in the second column of Table 2, summing up to a total of 4008. Also, the gender and age demographics distributions of the consistent sample are presented in Table 3. Questionnaires of non-consistent consumers were eliminated from all subsequent analysis. Also note that, where references are made to specific countries in the following text, this only refers to respondents from that country involved in this study. It is not meant to imply that the respondents are fully representative of the specified country. The first consumer habit to be identified was the washing temperatures used for each of the different clothing items that are washed. The weighted average of washing temperatures per washing item is presented in Table 4. The highest wash temperature (52.2°C) is used for washing linens and towels while the lowest (31.0°C) is used for washing the delicate items. Consumers in Russia use the highest temperatures for each clothing item except underwear; in this case, the German consumers use the highest temperature. On the other hand, consumers in the UK use the lowest temperatures in washing whites, linens and towels, while among the remaining clothing categories, they use the lowest washing temperatures. Moreover, these results exemplify that huge differences exist for the washing habits in the five European countries examined: for the linens and towels, the washing temperature difference between Russia (highest temperature) and the UK (lowest temperature) is 15 K while for the underwear washing temperature, the difference between Germany (highest temperature) and the UK (lowest temperature) is 13 K. The differences in the washing temperatures among the five countries do not differ significantly for coloured and delicate clothing items. The next question was about the information that consumers receive from the care labels of the clothes, as guidelines on washing can be found on the label attached to every clothing item. Fig. 1 presents the results obtained from each one of the five countries for the question ‘Do you read care labels in garments and laundry items before washing?’ Most of the consumers in each one of the five countries claim that they read the care label all of the time. The highest percentage is found in Germany (64.5%) while the lowest is in Russia and Italy (47.3%). Also, many consumers claim that they read the care label only for new garments. Overall, approximately 85% of the total sample claims that they read the care label at least once. This is a very promising finding because in this label important information is found regarding the care of the garment. However, one has to be very careful; it is one thing to read a label, another thing to comprehend its meaning. And of course, the most important thing of all is to correctly apply the guidelines given to you for the care of the garment during washing. Answers to question: ‘Do you read care labels in garments and laundry items before washing?’ Table 5 presents the results per country of the water hardness in the area of residence. These results are based on the self-reported knowledge of the respondent, because the actual water hardness measurement requires a chemical analysis. Alternatively, accurate water hardness data could have been obtained from the water suppliers, but doing this would have required the respondents' post codes and these were not collected in the survey. Note that water hardness varies even within a country, depending on the source of the water supply of each area. Normally, water originating from underground aquifers has higher hardness (Godskesen et al., 2012). The percentage of respondents reporting that they live in areas with hard water ranges from 30.7% (in Italy) to 40% in Russia. On the other hand, the respective percentage of respondents reporting that they live in areas with soft water ranges from 10.1% in Italy to 22% in the UK. These results indicate that people are aware of the water hardness of the area that they live in or at least that they have a perception of knowledge of the water hardness. Hard water may lead to precipitation of CaCO3 on surfaces in contact with water, particularly in devices operated at elevated temperatures such as washing machines (Van der Bruggen et al., 2009). These mineral deposits resulting from water hardness are reported to shorten the life of the washing machines: the lower the water hardness, the longer the service life of household appliances (Cameron, 2011; Godskesen et al., 2012). In order to check the hypothesis ‘Is the washing machine age affected by the water hardness of the area that the machine is operated in?’, consumers in the five countries were asked to report the age of their washing machines. The results are presented in Table 6. From there it is evident that in each one of the five countries examined, more than 70% of the washing machines are between 1 and 6 years old. Also, approximately 10% of the washing machines in each country were bought during the past 12 months from the date that the research was contacted. Among the most important logistic regression results presented in Table 7, it is observed that the odds ratio for water hardness indicates that when holding all other variables constant, if the water is soft, it is 1.262 times more likely to own a washing machine over 7 years of age, compared with hard or medium hard water. Also, the odds ratio for the weekly wash loads indicates that when holding all other variables constant, if the number of weekly wash loads is less or equal than four it is 1.791 times more likely to own a washing machine over seven years of age, compared with five weekly wash loads or more. In other words, the regression indicates that washing machines in soft water areas last slightly longer than those in medium hard or hard water areas; also washing machines that are used less than four times a week last longer than whose that are used more often. The next task was to identify the consumers' satisfaction from the washing result by asking them ‘Are you generally satisfied or dissatisfied with the washing result of your laundry?’ The responses were given on a Likert-type scale ranging from ‘Very satisfied’ to ‘Very dissatisfied’. As presented in Fig. 2, most of the consumers in all five countries are somewhat satisfied by the washing result. The respective percentage ranges from 50.8% in Russia to 70.3% in France. Very satisfied consumers from the washing result can be mostly found in the UK (40.9%) and Russia (39.3%). Degree of satisfaction from the washing result. As already reported in the literature, the washing result, and thus satisfaction of consumers, depends on water hardness (Cameron and Brown, 1995). In order to test the hypothesis ‘Is the level of consumer satisfaction higher in soft water areas?’ for the responses of the present research, the chi-square test of independence was employed. For statistical purposes, a new category was created termed ‘not satisfied’, which includes the following three initial categories presented in Fig. 2: ‘neither satisfied, nor dissatisfied’, and dissatisfied’. The results presented in Fig. indicate that there is a significant difference in the degree of satisfaction with the washing result among the areas of different water hardness. the percentage of consumers that are not satisfied with the washing result is in hard water areas while the respective percentage is in soft water On the other hand, the percentage of consumers that are very satisfied in soft water areas is while the respective percentage in hard water areas is Overall, most people in hard water areas to to do to get a good but a significant number do Degree of satisfaction from the washing result water hardness (in all The next research was to identify which are the specific for not satisfied by the washing result. The consumers were asked to report kind of they when they are not satisfied with the washing result of their laundry. that they were not asked to report the degree of of their garments. one in three of those not satisfied by the washing result claims that removal is the the problem resulting from the white on the garments was mentioned by of the respondents. Finally, colour of garments and of white garments was the next by by on the garments by of the respondents. As reported in the literature, the level of water hardness an important role in the or of the washing process (Cameron and Brown, 1995). The effects of hard water are lime deposits on fabrics and the of the washing These termed as may cause discoloration of fabrics and make them harsh and scratchy to (Cameron, or in other water hardness the satisfaction of the consumer with the washing process. Thus, the next question was straightforward regarding the effects of on the quality of the quality of your the respondents, that does not the quality of the garments. However, of the respondents that makes their fabrics and harsh to touch, that makes their fabrics appear while of the respondents that the of their fabrics. The use of softened water in the has effects such as reduced of and laundry detergents and service of household appliances (Godskesen et al., 2012). in detergent to an for the but also to a significant of the impact of washing clothes, in of the but also for as is in the and of detergents (Cameron, 2011). Thus, water has of and (Van der Bruggen et al., 2009). Water can be by water (Godskesen et al., or at home using ion (Van der Bruggen et al., 2009). However, this is in both and because ion for which are then a that is and to (Van der Bruggen et al., 2009). more is the use of water in each washing water are available in the form of in most of the countries, the household water are to the a already present in any household detergent. Therefore, the effect of water hardness on the laundry can be also if consumers use the detergent by detergent found on every European detergent of the research was the identification of the of use of water as additives to the household laundering process. The reported use of water per country is presented in Table Approximately of the respondents in the UK have used a water on the other hand, of the report that they use water in every wash by the of them use water in every the chi-square test of it is revealed that the gender and age of the have a significant effect on the use of water only in Italy among the five countries. are more likely than to use water in every wash or three or four times a people in the age years are more likely to use water In order to test the research hypothesis ‘Do people in hard water areas use water more in every wash or three to four times a the chi-square test of independence was employed. The results, presented in Fig. the hypothesis that the percentage of people in hard water areas that use water is three times higher compared with the of consumers that use water while in soft water areas of water use water hardness (in all Water hardness is a factor in the of the washing process. For the first a research was conducted in five European countries at the perception of the consumers on the effect of the water hardness in the washing cleaning performance. In of water hardness, the respondents to be well aware that the areas that they live in with the water hardness. The results also indicate that satisfaction on the washing although reported in high depends on the water hardness. in hard water areas are less satisfied compared with those in soft water the that people the water hardness for the quality of the the percentage of people using water is in all the countries the results that people in hard water areas use water more compared with those in soft water the percentage of people in hard water areas and using water is of the study is that it was based on the self-reported water hardness and not on actual results of this water On the other hand, an of the present research be that many consumers are aware of the effect of water hardness on the of the washing and that they are various to this is required for the effect of water hardness on in other European countries. For the of the consumer research, from an by is