Green Cosmetics—The Effects of Package Design on Consumers’ Willingness-to-Pay and Sustainability Perceptions

Abstract

The cosmetics industry requires a long-term, sustainable vision to reduce its impact on the environment. Within this process, packaging is of critical relevance, as it impacts the ecological footprint of products and determines consumers’ perception of the product as sustainable and green while shaping their willingness to purchase the product. This article implements a mixed-methods design to combine theoretical insights with the opinions of experts and the perceptions of consumers. It elicits which packaging elements are the most important in determining consumers’ willingness to pay for green cosmetics and which are the most important regarding their perception of the product being sustainable and green. The results of the conjoint analysis-based study conducted in Germany indicate the predominance of the used materials for packaging over other characteristics (glass +EUR 1, bio-based materials +EUR 0.92, recycled plastic +EUR 0.75 vs. wood as base category). Labels (Veganblume +EUR 0.68, Cruelty-Free +EUR 0.11) and the availability of refill options (+EUR 0.61) score in second place, while coloring (black −EUR 0.2, green −EUR 0.11, brown −EUR 0.13 vs. white as the base category) and QR codes (+EUR 0.13) score last regarding participants’ willingness to purchase the product. The results also reveal a distinct difference between the order of attributes driving the willingness to pay and those driving the perception of the sustainability of a product. Regarding sustainability perception, the relevance of labels and color increases distinctly, while package material remains the dominant attribute.

1. Introduction

Due to the immense challenge of how to meet today’s needs while preserving natural resources for future generations, the topic of sustainability is shaping the political, scientific, and social debate on a global scale [1]. As a result, consumers have become increasingly aware of their behavior and purchasing decisions regarding their ecological and social impact. As consumer awareness continues to grow, sustainable cosmetics and personal care products, in particular, are becoming increasingly popular [2]. In the past decade, sales of natural cosmetic products in Germany have doubled. Around 1.48 billion euros were generated in 2021. The one billion euro sales mark was already reached in 2014. The trend toward sustainable consumption in the cosmetics trade is, therefore, continuing [3].

In addition to changing their behavior, consumers expect companies to act in a more ecologically responsible manner [4]. With consumer demand for environmentally friendly products as well as government regulations and targets, cosmetics companies are required to act economically successfully and to reduce the impact on the environment and climate with the help of environmentally friendly measures along the entire life cycle of a product: from raw material extraction to waste disposal [5].

While a pronounced literature base on green marketing and cosmetic products exists, research on consumer behavior and, in particular, consumer choices regarding cosmetic products remain rather limited. Avilés-Polanco et al. [6] and Kapoor et al. [7] provide the sole study with a focus on the characteristics of cosmetic products determining consumer choice. Avilés-Polanco et al. [6] is the only study implementing discrete choice experiments or conjoint analyses in the context of cosmetic products.

The product design of cosmetic products, i.e., their packaging, currently has only been the focus of the study by Srivastava et al. [8]. This gap in the literature can be found in the critical informational value it poses for producers, leading to the assumption that respective research might have been carried out by companies privately but never been published openly. For other products like foods, however, characteristics of sustainability and packaging, in particular labels, have already been well researched [9,10]. Similarly, the impact of green marketing on consumers’ purchasing decisions is well-researched [11,12].

While sustainability characteristics impact consumer purchase intentions, they more directly impact their perceptions of how sustainable and green the product is. In a retail environment where consumers become increasingly skeptical of green marketing endeavors, suspecting potential greenwashing [13], determining the drivers of products’ sustainability perception is of critical importance for marketing endeavors. Establishing a strong brand image of being green and sustainable can have distinct economic effects on purchase intentions and, thus, company sales and profits [14].

In conclusion, few studies on green marketing in the cosmetics industry are available. However, the literature on environmental advertising, green marketing as a strategic approach, and the expression of green marketing as a concept of corporate social responsibility can be identified [15,16]. Furthermore, the issue of sustainability in the cosmetics industry can be approached from different angles, e.g., from the perspective of consumers [17,18], the supply chain, raw materials [19], and manufacturers [14,20]. Most consumer-related publications mention the need to address the growing trend of sustainability in the cosmetics market [20].

Recently, the impact of packaging on consumers’ purchasing decisions has also been studied. In a study conducted by Saha [21], factors influencing consumers in the consumer goods industry in Bangladesh were analyzed. The findings revealed that packaging features such as color, packaging material, design, and innovations are the most important aspects influencing consumers’ purchasing decisions. In another study, it was found that the visual elements of a cosmetic product serve as the best carriers of the brand message and have the greatest influence on consumer perception and attention [8].

In summary, consumers’ purchase intentions, as well as their sustainability perception of products, are shaped by the product’s characteristics—particularly by those characteristics that are closely linked to sustainability, like labels. Empirical studies researching the effects of packaging characteristics of sustainable cosmetics on consumers’ purchase intentions and their perceptions of products’ sustainability nevertheless remain severely limited. The only existing study in this regard does not consider the European market. To close this research gap, the present study considers the following central research question.

Which sustainable packaging elements of a cosmetic product influence the purchase intention and sustainability perception of German consumers?

By answering this question, this article will contribute to the existing literature in four ways. It will be among the first studies to consider determinants of consumers’ purchase intentions in an empirical study and the first to combine the perspectives of experts and consumers. It will also report on the situation for a major Western industrialized country with a developed cosmetics industry. With its focus on sustainability perception as well as the purchase decision, it will also provide a study to consider green marketing in the cosmetics industry in this context. Finally, the combination of both perspectives allows accounting for the relevance that green marketing plays in the context of consumers’ purchase decisions.

To make the central research question easier to operationalize, it can be split into three sub-questions.

RQ 1: Which sustainable packaging elements of a cosmetic product influence the willingness to purchase the product?

RQ 2: Which sustainable packaging elements of a cosmetic product influence the sustainability perception of the product?

RQ 3: To what extent does the sustainability perception of a cosmetic product impact the willingness to purchase the product?

To achieve the research objective and answer the three research questions, in the succeeding section, a brief introduction to the cosmetics industry is given and green marketing activities within the sector are discussed. This introduction is followed by an analysis of the literature regarding elements of sustainable packaging.

In the third section, the implemented mixed-method research design is introduced. Results are split across two sections. The fourth section presents the deductive expert-based qualitative study, whose main objective is the evaluation of the elicited characteristics of green packaging design. Building upon the results of the preliminary qualitative study, a quantitative study implementing a conjoint analysis with consumers is conceived, and its results are presented in the fifth section. The sixth and final section concludes by developing recommendations for academia as well as for practitioners.

2. Materials and Methods

2.1. The Cosmetics Industry

The cosmetics market is segmented into three pillars: body care market, fragrance market, and cosmetics market, with the sub-segments care and decorative cosmetics. Products within the cosmetics market can be sorted into different main business segments according to their use [22].

Over the past 20 years, the global cosmetics market has seen a strong market upturn of 4% [23]. Nevertheless, the global COVID-19 crisis did not leave this industry unscathed; in 2020, the sales volume fell by 9% to EUR 414 billion, a level similar to 2014 [3]. However, the global market for cosmetics and personal care recovered in 2021 and generated sales of around 425 billion euros [3].

Within the global cosmetics market, Germany has also seen a positive trend in sales of cosmetics and personal care products since 2013 [24]. According to projections by the Industrieverband Körperpflege- und Waschmittel (IKW), a total of more than 14.3 billion euros was generated in the 2022 financial year. Decorative cosmetics and perfume accounted for around a quarter of sales [25].

There was also a market shift within the German cosmetics market: natural cosmetics gained additional shares in a slightly declining overall market. Natural cosmetics were the only segment to record an increase in sales, namely by 1.8% to sales of 1.48 billion euros in 2021. The billion-euro sales mark was already exceeded in 2014 [26]. As a result, the market share of natural cosmetics was more than 10%, indicating the relevance of sustainability in cosmetics for German consumers.

2.2. Green Marketing in the Cosmetic Industry

Due to its continuous global growth and high consumption of natural resources, the cosmetics industry is one of the most important sectors that requires a long-term vision for managing sustainability [20].

Green marketing is a growing topic in the literature, although there have been few publications on the subject in the cosmetics industry to date [15]. This contrasts with business developments in which several cosmetics brands are achieving economic success while simultaneously minimizing their impact on the environment and climate, addressing aspects from the extraction of raw materials to waste disposal [5]. As an example, the world’s leading manufacturer of certified natural cosmetics, Weleda, has firmly anchored sustainability in the company and acts socially responsible, environmentally friendly, and economically successful [27].

As a result, the development of more sustainable, more circular, and more resource-efficient products offers brands the opportunity to gain access to new markets and new consumer groups [28].

The differentiation of consumers in terms of their sustainability attitudes and behavior poses a risk, as there are large and relevant differences in consumer behavior between types. There is also a gap between consumers’ knowledge and attitudes on the one hand and their actions on the other [29,30]. Nevertheless, a Utopia study found clear differences between sustainability-oriented and less sustainability-oriented consumer types. Tolerating higher prices for sustainable products is the decisive hurdle as to why consumers do not opt for more green products. Nonetheless, cosmetics companies can use green marketing to sensitize less sustainability-oriented consumers to environmental awareness and promote the consumption of environmentally friendly products [31].

Today, sustainability awareness is an integral part of mainstream attitudes and is present among a large majority of consumers [31]. However, as sustainability ideas increasingly appear in advertising (with the risk of greenwashing), concerns and confusion among consumers about which cosmetics brands are truly green and how they can trust them increase as well [15]. This is due to a lack of consistent regulation within the cosmetics industry, even though there are numerous optional non-governmental guidelines for natural or nature-based formulations [32].

Green marketing requires cosmetics companies to invest heavily in innovation and technology [15], as the development of sustainable products and the design of an environmentally friendly manufacturing process are linked to the coordination of knowledge and information as well as close cooperation between market research, R&D, procurement, and other areas of the company [33]. However, a green product policy offers the opportunity to achieve long-term savings through resource, energy, and transport efficiency, as well as waste minimization [20]. In addition, the careful selection of raw materials and their processing into primary products directly promotes product quality [34], and high product quality has a positive effect on both the perception of sustainability and the attitude of consumers [33].

In the context of green product policy, the sustainable design of the supply chain as well as of products is proving to be a challenge for companies.

2.3. Green Packaging Elements in the Cosmetics Industry

As part of green product policy, all sustainability aspects of a product are addressed, with a significant focus on the role played by packaging. Packaging design is an effective means of communication for providing information to consumers. It also enables a company to emphasize the differences between its products and the products of its competitors [8].

Cosmetics companies can use various elements to design sustainable packaging and communicate the ecological properties of the product. Those elements of packaging design can be divided into three categories: verbal, visual, and tactile [35,36].

Current trends in sustainable package design are summarized in

Table 1. Current trends in cosmetics packaging.

Trend	Examples
Recycled materials	Recycled paper Recycled plastics
Bio-based and bio-degradable materials	Mushroom-based materials Cork and wood
Reusability of packages	Refill options
Minimalism and packaging design priorities	Avoid unnecessary packaging layers Avoidance of unnecessary printing and labels Mono-material packaging
Eco-friendly ink and labels	Water-based and soy-based inks Avoidance of labels, print on package
Circular packaging and collaboration	Implement circular production system Recyclability of products Collaboration with recycling facilities
Smart packaging and consumer education	QR codes to reduce printing on package RFID chips Information on product use and disposal
Artificial Intelligence	Smarter recycling Smarter package design
Producer responsibility law-making	Hold producers responsible for the full product lifecycle
Transparency and traceability of materials	Establish sustainable packaging along the full value chain Avoid hidden

, and selected approaches are discussed in more detail in the subsections below.

2.3.1. Certificates and Labels

Sustainability labels or certificates on products serve to communicate product characteristics and information to the consumer by written or graphic means. In addition, the condensed presentation of the information means that consumers will face lower transaction costs when they find out about the environmental standards and requirements for the label [33].

From a corporate perspective, sustainability labels offer the possibility of sustainable and credible differentiation of product characteristics [37]. Such sustainability labels are used more frequently in the cosmetics industry in particular, as the large selection of supposedly natural cosmetics leads to uncertainty for consumers. For this reason, seals were developed with the purpose of better assessing various sustainability aspects of the product.

There are currently no uniform labeling standards in Germany. Around 230 sustainability labels are used in the EU [38]. The non-profit, international, and independent association COSMOS-Standard AISBL was founded to harmonize the European standards for natural and organic cosmetics [32].

2.3.2. Coloring

Colors are an essential factor in attracting attention to the packaging at the POS [39]. Around 62-90% of purchasing decisions are based on colors. The use of colors can help to differentiate products from those of competitors and also influence moods and feelings, thus attitudes toward certain products [40]. Colors are also used to convey different messages, as they evoke various associations in people [41].

2.3.3. Material

If a potential buyer has become aware of a product via the visual component, the material of the packaging plays an important role, as it not only acts as a protective cover but is also perceived by all the consumer’s senses [39]. The packaging material conveys direct expectations and emotions. This also happens unconsciously, which has a strong effect [42].

• Glass: Various studies suggest that consumers perceive transparent glass packaging as more honest, cleaner, more environmentally friendly, and of higher quality than other packaging [43]. Other associated characteristics are aesthetic, clear, safe, hygienic, and elegant [44].
• Plastic: One advantage of plastic is that it is relatively light, which has a positive impact on logistics costs [19]. Due to the ongoing debate about plastic waste, plastic packaging has a negative image among consumers in terms of environmental friendliness [39]. As a result, the cosmetics industry is trying to reduce the proportion of plastic and use more plastic with recycled content and compostable plastics, not least against the backdrop of EU initiatives to reduce plastic waste [1].
• Paper and cardboard: As materials, they have a warm appearance but do not allow a view of the product, which can be perceived as disturbing. Different surface treatments (glossy, matte, embossed, etc.) can be used to achieve diverse effects [45].

Environmental awareness among consumers has increased significantly recently. Consumers are more aware of the negative effects of poorly thought-out and superfluous packaging and packaging materials on the environment. In addition, there is a growing awareness that the packaging and packaging concepts of the past, which mostly consisted of complex mixtures of synthetically produced materials and non-degradable plastics, are no longer in line with responsible environmental attitudes [46].

Thus, cosmetic packaging is evolving, switching to the use of new sustainable materials from the agricultural industry (mushrooms, coconuts, bamboo, sugar cane, etc.) or forestry (wood, bark, etc.) [47]. On the one hand, these can enable differentiation and, on the other, convey the character of a handmade or exotic product [39]. New, green packaging ideas, however, bring with them concerns such as the permeability of the packaging, a shortened product shelf life, the lack of an appropriate disposal and recycling infrastructure, and possible negative effects on other sectors of resource use, e.g., agriculture [46].

Another approach manufacturers employ to minimize packaging material is implementing refill systems [1,48]. However, this sustainable solution is still underutilized by cosmetics brands despite growing consumer interest; a recent study reports that refillable skin care (up 42% year-on-year) and refillable lipstick (up 29% year-on-year) are among the search terms that saw the largest increase in Google search volume in 2022 [49].

2.4. Methodology

To answer the main research question and its sub-questions, a mixed-method research approach has been selected. Figure 1 illustrates the relationship between the different parts of the analysis and, thus, the article as such.

Motivated by the existing literature on the packaging of green products, the interview guide for expert interviews was constructed. To achieve the described objective of the qualitative preliminary study and to obtain a comprehensive approach, three guides were developed for the producer, consultant, and consumer perspectives. Figure 2 provides an overview of the thematic blocks of the interviews. It can also be seen that a certain degree of comparability of the topics and questions within the different perspectives was considered when creating the guidelines. In particular, the main section on packaging-related criteria was addressed in all three guidelines, as it poses the critical binding stone of the three parts of this study’s analysis.

Both theoretical insights and the results from the qualitative preliminary study provide the research design for the quantitative conjoint analysis. Focusing solely on the most frequently mentioned attributes, as they will be deduced in the first part of Section 3, leads to the following 4²2⁴3¹ research design for the conjoint study, detailed in

Table 2. Selected attributes and levels.

Attribute	Level 1 (Base)	Level 2	Level 3	Level 4
Color	White	Black	Green	Brown
Material	Wood	Glass	Bio-based	Recycled Plastic
Veganblume Label	No	Yes
Cruelty-Free Label	No	Yes
QR Code	No	Yes
Refill Option	No	Yes
Price	EUR 19.95	EUR 15.95	EUR 23.95

below.

To reduce the cognitive burden, an orthogonal instead of a full factorial design is implemented, leading to the use of 16 cards, which are still within the cognitive boundaries of participants of online surveys. Participants were asked to rate cards on a 5-point Likert scale according to their willingness to purchase the product and their assessment of how green they perceive the product to be.

The questionnaire used in the quantitative part was divided into five sections. In the first section, two questions were asked regarding the importance of sustainable cosmetics and the frequency of consumption.

“How important is sustainable cosmetics to you?”

“How often do you purchase sustainable cosmetics?”

Introducing the conjoint analysis, the participants were presented with instructions and an example to visually explain the process of rating the different product options. Section three comprised the actual conjoint study, i.e., the rating of the set of 16 orthogonal cards. Participants were asked to rate the likelihood of purchasing the displayed product and their perception of its sustainability using a 5-point Likert scale. In detail, the questions (translated from the German original) read as

“Please indicate to what extent you would buy the packaging based on its sustainable features.”

“Please indicate to what extent you perceive the product to be sustainable.”

The 16 cards were presented to them in random order to avoid a common method bias. Figure 3 illustrates, for one exemplary case, the design of the cards presented to the study participants (the card has been translated from the German original).

The fourth block of the quantitative survey was aimed at recording sociodemographic data. Finally, participants were free to leave their e-mail addresses to participate in a raffle as an added incentive for participation in the survey.

Summarizing results from both the qualitative and the quantitative parts of the study, recommendations for practitioners and future research will be deduced.

Ethical approval for the study has been granted by the ethics committee of the International School of Management under number K-2025-JP-03.

3. Results

3.1. Qualitative Expert Interviews

3.1.1. Expert Sampling

The sample of experts was compiled according to three different perspectives (producer, consultant, and consumer) to obtain as comprehensive a view of the topic as possible. Although the sample included the three intended target groups, the aspect of homogeneity was also considered. To find suitable interview partners, contact data has been researched via the list of external lecturers at business schools, i.e., primarily the International School of Management, as well as company webpages and LinkedIn profiles. Against the background of the research question on the design of sustainable packaging-relevant criteria, care was taken to recruit interview partners who have a more practical approach to the topic and work within the cosmetics industry. Regarding the consultant perspective, care was taken to ensure that the respective interviewee was particularly concerned with the topics of consumer behavior, sustainability strategy, and the consumer goods industry. Representatives from general cosmetics companies have been invited, as well as representatives from companies producing sustainable cosmetics. Due to assurances of anonymity, detailed information on the representatives’ background cannot be made available.

Ultimately, the interviewees from the consumer perspective were recruited from special interest groups on social media platforms. They should have a high level of interest in nature-based cosmetics and sustainable and environmentally friendly packaging.

A total of five interviews were conducted. Two of the interviewees could be assigned to the producer’s perspective. One expert was an advisory representative. Two interviews were conducted with representatives of the consumer perspective. The duration of the interviews was between 25 and 30 min.

While male industry experts have been invited to participate in the interview as well as female experts, all the industry experts who opted to take part in the interview study were female. Of the consumers, only women were interested in the interview study in the first place. Thus, all five experts were female.

3.1.2. Results and Discussion

Table 3. Results of the preliminary study.

Characteristic	Results
Color	Colors that evoke sustainable and natural associations are also, in my opinion, the most effective in influencing consumers. (I5, 12) I find white, transparent, brown, and black visually appealing for products, and I associate them with sustainability. (I1, 6) Definitely green. I find bright green rather modern, which contrasts with a more natural, brownish packaging. (I3, 6) In contrast, the Garnier Bio brand, which also belongs to L’Oréal, uses colors such as brown, white, and green. (I5, 4)
Material	Mostly, it is about […] recycled plastic. (I4, 10) Clear favorites for me are […] and glass. (I1, 15) I also consider glass to be sustainable because it is recyclable and does not release any substances into the cosmetics. Glass also looks high quality. (I3, 12)
Veganblume Label	I recently read that the vegan seal, i.e., the Veganblume, is one of the oldest seals in the cosmetics sector. In my opinion, it is also the most relevant at the moment. It is a seal that can be used universally. It is also easier to make a cosmetic product vegan. (I4, 6)
Cruelty-Free Label	The topics of vegan and cruelty-free are currently becoming increasingly important for consumers. Brands that want to appeal to this target group should, therefore, display seals such as Veganblume or Cruelty-Free. (I5, 6) For me, the Cruelty-Free label is very important so that I know that the products have not been tested on animals and so that I recognize the ethical sustainability criterion. (I3, 8)
QR Code	I could also imagine printing a QR code on the product itself, i.e., on the packaging, for example. You can call it up directly when you are in the store and get an idea of the product right there. (I1, 23)

summarizes the results of the qualitative preliminary study regarding the relevant determinants of sustainable cosmetics packaging.

Other comments in the visual elements category were sustainable packaging material and less packaging or reduced packaging quantity. In addition, the following packaging-relevant criteria for the appearance of the packaging design were identified from a consumer perspective: simplicity, tidiness, and uniqueness. The first interviewee attached particular importance to a product design that harmonizes in the bathroom.

The interest in less or reduced packaging can be targeted by considering refill options.

As far as the verbal elements of sustainable packaging are concerned, four interviewees mentioned ingredients. On the one hand, representative 4 from the producer perspective described that green advertising claims, such as “ingredients of natural origin. Ingredients from sustainable agriculture” (I4, 10), are particularly effective in terms of sustainable perception. On the other hand, the second product manager described: “There has been no focus on the ingredients so far, as most consumers do not really understand the chemical and Latin terms” (I4, 8).

The second representative from product management also stated that information on the recycled content of the packaging is a common element. Three out of five interviewees mentioned free-from claims, such as silicone-free, paraffin-free, microplastic-free, and cruelty-free, regarding the sustainable perception of a cosmetic product.

A further packaging criterion can be derived from this statement: information on the percentage of plastic that can be saved by the respective sustainable packaging. Further statements in the verbal elements category were the brand name, information on the country of origin, and information on FSC certification for outer packaging.

All of these criteria can be summarized under the heading of additional information that can be provided to the customer via QR codes.

3.2. Consumer Perspective

3.2.1. Description of the Sample

The survey has been disseminated both actively and passively. First, the distribution of the survey took place among special interest groups on social media and among university students. Second, flyers sporting a QR code for participation in the survey were handed out to interested passersby in front of cosmetics retail stores. Finally, the flyers were placed at the check-out counter at the store of a major German cosmetics retailer. While this process resulted in a convenience sample, it assured voluntary participation without participants feeling pressured to participate or answer in any way, and it additionally assured the participants’ anonymity.

After pre-processing of the data, i.e., exclusion of incomplete surveys and one case where the participant stated an age below 18, a total of 163 valid data records resulted. While participants had the option of opting out on questions regarding gender, age, and income, eleven people stated that they were male, and 152 people that they were female. With a median age of 29.38 years, 30.67% of the participants were between 18 and 24 years old, 44.17% between 25 and 34 years, and 4.91% between 35 and 44 years. Thus, 79.75% originate from the generations Z and Y, with the remaining 20.25% originating from older generations.

In addition to gender and age, the financial situation was surveyed as a sociodemographic characteristic. Net income was divided into 12 groups for this study. In total, 13.5% of respondents classified themselves in the EUR 2001–2500 income bracket, which therefore accounted for the largest proportion. An income of between EUR 1501 and 2000 accounted for the second-largest share at 12.3%. A further 10.4% of participants stated that they earned a net income of between EUR 500 and EUR 1000, resulting in a median income of EUR 2046.36. The sample shows that income is strongly related to the age of the respondents. It can be assumed that a higher age implies a higher income, particularly in relation to the respective life circumstances and more extensive professional experience.

Summarizing, the sample was dominated by female participants from generations Y and Z, and the median income reported a value slightly above the median for the German population in total. Considering that the German cosmetics market primarily targets women, the gender distribution does not surprise. With a stronger interest in sustainability issues among the younger generation, a respective age and income bias resulting from the self-selection inherent in the implemented convenience sample does not surprise either. Thus, the sample primarily reflects the perceptions of a younger, female, and more sustainability-sensitive clientele, who incidentally also constitute the majority of consumers of sustainable cosmetics.

3.2.2. Results

Using the information about the levels displayed on each of the evaluated cards yielded a total of eleven predictor variables. In this context, level 1 of each attribute has been set as the base level with which all other levels are compared. Thus, the reference category for the attribute color is white, and for the material attribute, it is new plastic. For the others, the base category is the absence of the attribute. The base price, resulting from averaging comparable products in the German market, is set to EUR 19.95.

An additional interaction term was considered, combining the color green and primary packaging material made from bio-based material to check whether this archetypical packaging style generates an additional impact, as was hinted at in the course of the expert interviews.

Table 4. Regression results.

		Purchase Intention Willingness-to-Pay			Sustainability Evaluation		Joined
		Model I	Model II	Model III	Model IV	Model V	Model VI
Color	Black	−0.144 *** (0.054) EUR −0.25	−0.144 *** (0.054) EUR −0.20	−0.144 *** (0.054) EUR −0.20	−0.089 * (0.052)	−0.089 * (0.052)	−0.085 ** (0.042) EUR −0.28
	Green	0.060 (0.054) EUR 0.10	−0.077 (0.077) EUR −0.11	−0.077 (0.076) EUR −0.11	0.195 *** (0.052)	0.190 *** (0.073)	−0.203 *** (0.059) EUR −0.20
	Brown	−0.090 * (0.054) EUR −0.16	−0.090 * (0.054) EUR −0.13	−0.090 * (0.054) EUR −0.13	0.195 *** (0.052)	0.195 *** (0.052)	−0.220 *** (0.042) EUR −0.22
Material	Glass	0.733 *** (0.054) EUR 1.24	0.733 *** (0.054) EUR 1.00	0.733 *** (0.054) EUR 1.00	0.816 *** (0.052)	0.816 *** (0.052)	0.192 *** (0.044) EUR 0.62
	Bio-based Material	0.811 *** (0.054) EUR 1.37	0.675 *** (0.077) EUR 0.92	0.675 *** (0.076) EUR 0.92	1.057 *** (0.052)	1.052 *** (0.073)	−0.023 (0.061) EUR −0.08
	Recycled Plastic	0.544 *** (0.054) EUR 0.93	0.544 *** (0.054) EUR 0.75	0.544 *** (0.054) EUR 0.75	0.686 *** (0.052)	0.686 *** (0.052)	0.090 ** (0.043) EUR 0.21
Labels	Veganblume	0.428 *** (0.038) EUR 0.74	0.496 *** (0.047) EUR 0.68	0.496 *** (0.047) EUR 0.68	0.650 *** (0.037)	0.653 *** (0.045)	0.063 * (0.038) EUR 0.21
	Cruelty-Free	0.146 *** (0.038) EUR 0.25	0.077 * (0.047) EUR 0.11	0.077 * (0.047) EUR 0.11	0.276 *** (0.037)	0.274 *** (0.045)	−0.104 *** (0.036) EUR −0.35
	QR Code	0.160 *** (0.038) EUR 0.28	0.091 * (0.047) EUR 0.13	0.091 * (0.047) EUR 0.13	0.186 *** (0.037)	0.183 *** (0.045)	−0.030 (0.036) EUR −0.10
	Refill Option	0.373 *** (0.038) EUR 0.64	0.441 *** (0.047) EUR 0.61	0.441 *** (0.047) EUR 0.61	0.454 *** (0.037)	0.456 *** (0.045)	0.138 *** (0.037) EUR 0.45
Price	Price	0.589 *** (0.111)	0.743 *** (0.127)	0.743 *** (0.126)	0.650 *** (0.107)	0.655 *** (0.121)	0.308 *** (0.098)
	Price squared	−0.015 *** (0.003)	−0.019 *** (0.003)	−0.019 *** (0.003)	−0.016 *** (0.003)	−0.017 *** (0.003)	−0.008 *** (0.003)
Controls	Interaction Term	-	0.546 ** (0.217) EUR 0.75	0.546 ** (0.216) EUR 0.75	-	−0.018 (0.207)	0.534 *** (0.167) EUR 1.69
	Gender	-	-	−0.184** (0.076)	-	−0.393 *** (0.073)	0.076 (0.059)
	Age	-	-	−0.053 *** (0.017)	-	−0.015 (0.015)	−0.043 *** (0.013)
	Constant	−3.535 *** (1.072)	−4.824 *** (1.187)	−4.458 *** (1.187)	−4.583 *** (1.029)	−4.158 *** (1.138)	−1.700 * (0.919)
	Sustainability Evaluation	-	-	-	-	-	0.663 *** (0.016)
	R2	0.181 ***	0.183 ***	0.189 ***	0.295 ***	0.303 ***	0.516 ***
	N	2608	2608	2608	2608	2608	2608

Note: asterisks indicate the significance level: * 10%, ** 5%, *** 1%; the R² row denotes the significance of the F-test.

shows the results for regressions in the context of six models. Models I through III target the first research question about the purchase intention. Thus, the dependent variable in all three models is the participants’ evaluation of how likely it is that they would purchase the product. Model I is the base model without control variables, while Model II includes the interaction term and Model III the sociodemographic variables gender and age.

Models IV and V target the second research question about the sustainability perception of cosmetic products. Here, the dependent variable is the evaluation of how sustainable they perceive the product to be. Model IV is the base model, and Model V includes the interaction term and the two sociodemographic variables.

Finally, Model VI targets the link between the sustainability perception of the products and the participants’ willingness to purchase them. Thus, the dependent variable is the participants’ likelihood of purchasing the product. The model is identical to Model III, but for the inclusion of the sustainability perception of the product.

In a preliminary conjoint analysis, the results implied a quadratic effect on the price. As a result, squared prices were added to the regression. Calculating the willingness-to-pay (WTP), therefore, required the following formula.

$${\mathrm{W}\mathrm{T}\mathrm{P}}_{\mathrm{i}}=\left({\mathrm{p}}_1+2{\mathrm{p}}_1{\mathrm{p}}_2\right)-{\displaystyle \frac{\sqrt{{\left({\mathrm{p}}_1+2{\mathrm{p}}_1{\mathrm{p}}_2\right)}^2-4{\mathrm{p}}_2{\mathrm{c}}_{\mathrm{i}}}}{2{\mathrm{p}}_2}}$$

(1)

The index i marks the i-th characteristic, and thus c_i is the coefficient of the i-th characteristic. p₁ is the coefficient of the price variable, and p₂ is the coefficient of the price variable squared.

In the table, results are structured by attributes. For each variable, the first row reports the coefficient, the second the standard error, and the third the WTP in Euro.

The results for the WTP are additionally summarized in

Table 5. Willingness-to-pay as a heatmap.

		Purchase Intention Willingness-to-Pay		Joined
		Model I	Model II	Model III	Model VI
Color	Black
	Green
	Brown
Material	Glass
	Bio-based Material
	Recycled Plastic
Labels	Veganblume
	Cruelty-Free
	QR Code
	Refill Option
	Interaction Term

Note: dark red: negative WTP; light red: WTP EUR 0–EUR 0.1; yellow: WTP EUR 0.1–EUR 0.5; light green: WTP EUR 0.5–EUR 1; dark green: WTP EUR 1+.

in the form of a heatmap, illustrating those characteristics that are of particular relevance to increasing the WTP. In the case of red cells, the base level is the preferred alternative.

4. Discussion

4.1. Which Sustainable Packaging Elements of a Cosmetic Product Influence the Willingness to Purchase the Product?

Models I through III indicate, in comparison, that results remain unchanged even if controls for the participants’ gender and age are included. Only the inclusion of the interaction term leads to minor changes in the coefficients and the marginal willingness to pay.

The attribute with the strongest effect is the materials. Compared to the base category wood, all report a significantly higher WTP. The preferred packaging materials, thus, are bio-based materials, closely followed by glass. The strong prevalence of glass does not surprise, since it is the most commonly used and easiest to recognize of the considered materials; thus, consumers are already used to seeing it.

Multiple articles stressed the relevance of labels so that the strong effect of the Veganblume label does not surprise. The comparatively weak effect of the cruelty-free label, however, does. QR codes, which act partially like labels, are considered similar to the cruelty-free label.

The refilling option, added only after mentions by the experts, reports the third-highest relevance for the participants, stressing the need for future studies to more closely consider this gap in the literature.

Finally, coloring is the least effective tool to impact participants’ WTP for cosmetics. While reporting only minor deviations from the base color white, only green is marginally better perceived, not significantly, though. The only color reporting a pronounced negative effect on the participants’ WTP is black.

The interaction effect reports a significantly strong effect on the WTP, illustrating that while the color green on its own might not have an effect if combined with the right materials, it will strongly impact consumers’ WTP, creating an additional benefit for potential buyers, which equals a value of EUR 0.75.

Finally, it can be observed that men are less interested in green cosmetics than women and older participants are less interested than younger ones. Both results coincide with general results on sustainable purchasing behavior.

The coefficient of the prices reports a significantly positive sign across all models. It can thus be deduced that higher prices are associated with a higher willingness to purchase the product and a higher perception of sustainability. This gives rise to the assumption that, regarding green cosmetics, prices fulfill a signaling role and consumers relate a higher price with higher quality expressed via them being greener. Alternatively, at a certain level, green cosmetics report a demand like a luxury good.

Since the prices are quadratic and the quadratic term is highly significant as well, this might indicate two things. At relatively low prices, the demand curve is negatively sloped, representing a normal good. Beyond the selected base price, it becomes more akin to a luxury good. Thus, pricing policy can have a distinct impact on the perception of customers’ perception of the cosmetic product. Alternatively, prices might have a secondary signaling function for green cosmetics. With low-priced cosmetics, customers are wary of their quality, while with high prices, they equalize high prices with high quality and react accordingly.

4.2. Which Sustainable Packaging Elements of a Cosmetic Product Influence the Sustainability Perception of the Product?

While the results in Models IV and V mirror those of the first three models regarding the prevalence of the materials, labels, and even the price, the effect of the colors distinctly changes.

Regarding sustainability perception, the colors green and brown both report significantly positive effects. The effect of black is still significantly negative, but only barely, indicating that it should still be avoided, but the harm it causes is less pronounced as compared to its effect on the purchase intention.

The ranking across materials, interestingly enough, is the same as in the context of the WTP. Since, in both contexts, the materials play a major role, the results already hint at the linkages between the two perspectives. Considering the slightly weaker effect on the WTP, a mediating role of the sustainability perception thus seems reasonable to assume.

Regarding the two considered labels, again, the cruelty-free label ranks significantly below the Veganblume label, illustrating that it is the one best suited for companies that aim to transmit an image of authentic sustainability. While still effective, since they are significant and report positive coefficients, the cruelty-free label and QR codes are only second-choice options.

The inclusion of the interaction term and the sociodemographic variables leads to only marginal changes in the coefficients. Thus, the results can be considered stable across gender and age.

Comparing the coefficients of determination across the first three models, they report values around 18%. While indicating a moderately strong explanatory power of the model, they are also a sign that still a solid amount of information is missing when considering the purchase decision of green cosmetics.

Models IV and V, in comparison, report coefficients of determination of approximately 30%, displaying thus a strong explanatory power. The chosen predictors thus work much better for the evaluation of cosmetics sustainability perception. However, even though they are the central aspects mentioned in the literature and by experts, the analysis revealed that a significant portion of understanding the sustainability perception of products is still missing.

4.3. To What Extent Does the Sustainability Perception of a Cosmetic Product Impact the Willingness to Purchase the Product?

Model VI only deviates from the third model by including the sustainability perception as an independent variable. While the coefficients and, thus, the potential effects of the predictors change drastically, additional testing reveals that these changes are not the result of high multicollinearity within the model.

Similar to Model III, all colors report negative signs, which are all significant. Since the comparison is with the base color white, the results point to the packaging ideally being as colorless and light as possible.

Concerning the materials, glass remains the best-suited material, followed by recycled plastic. In addition to the argument given regarding RQ 1, this indicates that the positive impact of bio-based materials, as conjectured above, comes primarily from its positive sustainability perception, which, in this case, is covered by the overall sustainability perception.

The effect of the Veganblume label remains positive and significant, even only slightly, while the sign of the cruelty-free label becomes significantly negative. While the reduced effect of the Veganblume label is not surprising, the negative effect of the cruelty-free label indicates that participants would actively try to avoid products with this label if it were not for its sustainability signaling reason. Thus, a company deciding on which label to adopt would be well advised to select the Veganblume label over the cruelty-free label. Similar arguments hold for the now rather neutral QR codes.

Quite surprising is the strong significance and the positive sign of the refill options. Introduced by the experts as an additional tool of green marketing and raising the sustainability perception of products, they possess additional value to consumers beyond their marketing potential.

While the age variable is consistently negative, indicating that older participants are less inclined to purchase green cosmetics, the significance of the gender variable disappears in this model. In conclusion, gender effects can be attributed to differing perceptions of sustainability, a conjecture supported by the results of the second research question.

Finally, Model VI reports a coefficient of determination of 51.6%, which indicates a strong explanatory power and that the model can now explain more than half of the variance of participants’ preferences concerning the purchase of green cosmetics. The strong effect of the sustainability perception of the product is not only an additional incentive for companies to enact green marketing. It also underlines the need to understand the determinants that drive the sustainability perception of their products; thus, it provides a retrospective validation of the objective of this study.

5. Conclusions

5.1. Recommendations for Practitioners

Building on the results from the study, recommendations regarding the different packaging elements as well as means of communicating with consumers can be elicited.

5.1.1. Packaging Elements—List of Ingredients

Based on the qualitative study, it was established that the list of ingredients is an important verbal element for drawing conclusions about the quality and sustainability of the respective cosmetic products. In this context, interviewees criticized that individual designations are neither understandable nor comprehensible. As a result, brands of skincare and cosmetic products should clearly list the origin of each ingredient on the packaging in consumer language. The presentation of this key information would also have a positive effect on limited purchasing decisions. In this way, cosmetics brands could positively influence consumers who only have limited shopping time available.

5.1.2. Packaging Elements—Labels and Certificates

The qualitative study determined that the visual design element can serve as an orientation framework and enable product characteristics to be differentiated. However, there are currently numerous labels in the cosmetics industry with different focuses and award criteria. This leads to confusion for consumers. Accordingly, cosmetics brands should communicate the meaning of the respective labels clearly and transparently on the packaging with the help of symbols and concise statements.

5.1.3. Packaging Elements—Colors

Around 62-90% of purchase decisions are based on colors [39] (p. 140). This is confirmed by the importance values resulting from the conjoint analysis. The participants preferred the color green for a sustainable cosmetic product. From this, it can be deduced that green shades trigger stimuli and evoke learned associations or attributions to the other.

5.1.4. Packaging Elements—Packaging Material

The qualitative study revealed that the packaging material is perceived both visually and haptically and thus conveys direct expectations and emotions. The results of the conjoint analysis also revealed that consumers are open to new, sustainable packaging, such as that made from bio-based materials. Accordingly, cosmetics brands should work more closely with innovative material manufacturers and further advance the development of environmentally friendly packaging. However, companies in the cosmetics industry must also negotiate with legislators and work with them to find a solution as to what requirements there are for sustainable packaging and how these can be implemented without violating product regulations.

5.1.5. Means of Communication—QR Codes

The qualitative study revealed that a QR code on the product packaging or on the shelf is ideally suited as an information tool at the physical point of sale. This design tool offers the opportunity to provide interested consumers with a transparent and compact overview of product information, sustainability initiatives, and statements on environmental compatibility, for example.

5.1.6. Means of Communication—Customer Education: Sales Staff as Brand Ambassadors for Sustainability

Only very well-informed sales staff who are familiar with the sustainable product manufacturing, price/performance features, and sustainability philosophies of the various manufacturers in the cosmetics industry, and who can understandably explain these to the end consumer, will be able to convince them to make a purchase. Here, a discussion guide could help to strategically and successfully optimize important facts and arguments and present the respective cosmetic products in an understandable and convincing way. It is also recommended that the ambassadors continuously draw the attention of consumers on the sales floor to the value-creation steps of consumption, as well as disposal and recycling.

5.2. Limitations and Outlook

The main challenge of translating the results of the qualitative study into a research design for the conjoint study was the limited cognitive capacity of the participants, which led to the use of a reduced design with 16 cards implementing seven attributes. However, in an actual shopping situation, many more packaging and product attributes play a role for consumers. Therefore, future research should further study how other parameters, such as the list of ingredients, product promises, or packaging shape, influence consumers’ purchasing decisions.

Furthermore, the consumer survey focused exclusively on the skin care product category since the fictitious packaging of a jar was to be presented as realistically as possible for the participants. Future research could use a choice-based design to study preferences in other product categories. In addition, an investigation could be integrated to determine whether significant differences can be identified concerning quality and sustainable attributes, such as the material.

From a methodological perspective, the study has been based on a conjoint study that has been evaluated by the use of a standard regression approach. While no distinct issues with multicollinearity have arisen, the research design gives rise to a more sophisticated approach, like the use of a PLS-SEM. Additionally, the mentioned switch to a discrete choice-based design for the quantitative study would not only alleviate the cognitive burden for the participants and raise the quality of the results but would, at the same time, allow for more detailed study approaches that incorporate classification of the participants, like latent class multinomial logit estimations. Finally, the questions regarding the purchase intention and the sustainability perception have been asked next to each other per displayed card. This process might give rise to a second degree of common method bias. Even though the results of this study give no reason to assume its presence, a future study might avoid it from the outset.

A question that has been beyond the scope of this study but might provide distinct value to companies would be to estimate the additional impact of the brand image on the purchase decision as well as on the sustainability perception.