Sustainable cosmetic ingredient alternatives to replace conventional ingredients: Case studies in moisturizers and lipsticks

Abstract

Objective

Over the last two decades, consumers have been calling for greater transparency for ingredient sourcing and manufacturing practices; therefore, more sustainable alternatives need to be evaluated to meet industry demands. While many organizations give standards for ‘clean’, ‘organic’ and ‘natural’ cosmetic products, sustainable formulations lack standardization and harmonization globally. This study aimed to formulate sustainable lipsticks and moisturizers using resources and standards currently available in the cosmetic industry and compare select sustainable alternatives to a conventional control product.

Methods

After thoroughly screening ingredients for each product type, five different lipsticks and five batches of moisturizers were formulated and tested for quality, performance and stability characteristics.

Results

Pay‐off and friction were the most different among the lipsticks, with M4, the lipstick containing sustainable ingredients, having the highest average friction and pay‐off at Week 1. As for the moisturizers, spreadability had the largest differences, mostly due to the different emulsifier systems, as expected.

Conclusion

Incorporating sustainable ingredients can be challenging, but having quality products while being more environmentally friendly is possible. These case studies are meant to serve as examples for formulation chemists.

Project outline from ingredient selection and screening to lipstick and moisturizer formulation, testing results and overall conclusions.

INTRODUCTION

Over the last two decades, the values of cosmetic consumers have shifted, and the everyday consumer has become more conscious about product claims. In 2021, the global sustainable personal care market was valued at $50.8 billion and is projected to grow to $129.7 billion by 2031 [1]. Consumers are calling for greater transparency in ingredient sourcing and manufacturing practices; therefore, more sustainable alternatives need to be evaluated to meet industry demands. Environmental and health concerns have created a new market segment in the beauty industry that is targeted by green marketing [2]. Green marketing uses buzzwords like ‘organic’, ‘natural’, ‘hypoallergenic’ and ‘clean’ to attract consumers who want naturally derived ingredients or sustainable packaging [2, 3]. The shift towards these products has resulted from the perception that these products are safer and more consumer‐ and environment‐friendly [4].

While the Food and Drug Administration (FDA) does not regulate these green marketing claims, ingredients and products can receive certifications from organizations with their definitions. Many organizations like Credo Beauty, One Planet and Pact Collective provide standards on sustainable packaging for cosmetic products and offer certifications for sustainable packaging [5, 6, 7]. While many organizations give standards for ‘clean’, ‘organic’ and ‘natural’ cosmetic formulations, sustainable formulations lack standardization and harmonization across the nation and world [8].

The Research Institute for Medicines created an Excel sheet as a tool to assess sustainability in cosmetic products [3]. This calculator generates a score based on five categories, including a product's raw materials, production, packaging, distribution and post‐consumer fate [3]. The calculator has a series of ‘Yes or No’ questions and a table that requires the ingredient percentages to be recorded. The challenge with this type of tool is that the information needed to calculate the score might only be available to the supplier and not the manufacturer or brand. This creates a dilemma because comparing sustainable alternatives might take an unreasonable amount of time with this tool alone. A potential solution in the future could include internal sustainability experts who facilitate the comparison of sustainable ingredients with conventional ingredients. Having this information readily available at ingredient suppliers would also be ideal.

When considering a cosmetic formula's life cycle and aesthetics, the selection of raw materials has the greatest impact on sustainability [9]. The 12 Principles Green Chemistry can be applied to any product lifecycle to improve the environmental impact [10, 11]. In this study, some of the principles used to screen and select ingredients included ‘Use Renewable Feedstocks’ and ‘Design for Degradation’ [11]. For example, shea butter was used as a sustainable substitute for petrolatum because the specific raw material was derived from a renewable source, the African Karite tree [8]. Another example of sustainable ingredient selection is using candelilla wax as a substitute for ozokerite. Candelilla wax is derived from the plant Euphorbia Cerifera and is a renewable source compared with ozokerite, which is derived from minerals [12]. Additionally, unlike ozokerite, candelilla wax can degrade once disposed of [13]. Further investigation into raw materials that incorporate more Principles of Green Chemistry like ‘Upcycling’ (i.e. waste prevention) and ‘Designing Safer Products’ could increase the overall sustainability of products [11].

Research groups have started evaluating the impact of replacing conventional ingredients with sustainable alternatives. For example, Bom et al. formulated a series of emulsions with sustainable alternatives to petrolatum, dimethicone and phenoxyethanol [14]. The emulsions were tested for physicochemical properties, sensory effects, skin moisturization and safety [14]. It was found that replacements affected mainly the emulsions' rheological behaviour [14]. A series of troubleshooting steps were needed to adjust product quality, for example, adding a surfactant and a gelling agent. The study demonstrated that achieving comparable product quality is possible when replacing conventional ingredients [14]. Another research group, McInstosh et al., studied the effect of alkenones as a sustainable alternative for conventional waxes in lipsticks, lip balms and skin creams [12]. Their results showed that the sustainable alternative was comparable to the control in performance and product quality [12]. While published studies exist, the principles of green chemistry were not always considered when selecting alternatives. Commercial products formulated with sustainable ingredients are also available today (based on ingredient list and possibly the product claims); however, it is not possible to determine whether the ingredients are natural, naturally derived, nature identical or synthetic, as this information is not part of the INCI names. Therefore, it is not possible for research groups and consumers to evaluate the sustainability approach of a product.

Sustainable product development is not a linear process and the strategy for sustainable development must evolve constantly to keep up with the changing market and innovations. Since the term ‘sustainable’ is a broad claim and is not harmonized globally, it can be overwhelming to make all aspects of a product sustainable, including raw materials, manufacturing processes and certifications, especially for small businesses or growing companies. Companies need to conduct market research to better understand the values of their consumers regarding sustainable claims and product characteristics. Once these core values are established, implementing green chemistry principles in a company's product development process can be more strategic. For example, a company's audience might deeply care about products made with renewable and biodegradable ingredients. While finding energy‐efficient and sustainably sourced ingredients is important for this example company, recognizing the difficulty of finding ingredients that meet all those conditions is crucial to creating a prioritization system. Strategic, sustainable action can impact the consumer and the environment. The work and research put into the sustainable development of the first product builds on itself for subsequent products. Eventually, a company's library of sustainable ingredients and knowledge of sustainable processes could help save time and money compared with starting each sustainable product development project from scratch. As mentioned above, an internal sustainability expert or third‐party consultant could facilitate the comparison of sustainable ingredients to conventional ingredients and help streamline the process.

In this study, the selection criteria had three major categories to consider all production phases when selecting raw materials, including (a) the manufacturing process, (b) physiochemical properties and (c) certifications [3]. The manufacturing process includes ingredient development, transportation and any energy‐intensive processes contributing to making a product or ingredient [3]. To effectively replace ingredients, the alternatives need to have similar physiochemical properties, such as appearance, melting point and viscosity. Finally, as mentioned above, ingredients can have certifications from certifying bodies, such as natural, biodegradable and organic, that help show companies they meet a certain standard.

The goals of this study were to (1) formulate sustainable products using resources and standards currently available in the cosmetic industry, (2) evaluate the sustainable ingredients in skin moisturizers and lipsticks and (3) compare the sustainable products to a control in quality, performance and stability tests. With the increasing demand for sustainable products, this research is meant to serve as an example and guidance for ingredient selection and formulation strategies for companies looking to create sustainable products. Understanding the chemical properties of sustainable raw materials will help companies predict stability, performance and aesthetic challenges [15].

MATERIALS AND METHODS

Materials

Lipstick ingredients that were screened for various physicochemical characteristics are listed in Table 1. The colour dispersion was created in‐house based on our previous method [12]. The pigment dispersion and antioxidant did not have sustainable alternatives. Cream ingredients that were screened are summarized in Table 2. All ingredients were of cosmetic grade in the lipsticks and moisturizers.

TABLE 1.

Lipstick ingredients screened for physicochemical properties in this study.

Function in product	INCI name | Trade name	Supplier (name and location)	Used in control product	Used in sustainable product
Lipstick wax, structuring agent	Microcrystalline wax | Microcrystalline wax	Making Cosmetics, Redmond, WA	x
	Ozokerite | Ozokerite	Making Cosmetics, Redmond, WA	x
	Synthetic beeswax (and) synthetic wax (and) stearic acid | Synthetic Candelilla Wax R‐4	Koster Keunen, Watertown, CT	x
	Beeswax | NF white beeswax	Koster Keunen, Watertown, CT		x
	Euphorbia Cerifera (candelilla) wax | Candelilla wax	Koster Keunen, Watertown, CT		x
	Copernicia Cerifera (carnauba) wax | Organic carnauba wax	Koster Keunen, Watertown, CT		x
Lipstick emollient, skin conditioner, stick softening agent, glide enhancer	Ethylhexyl palmitate | Ethylhexyl palmitate	Making Cosmetics, Redmond, WA	x
	Caprylic/capric triglyceride | Triglyceride	Making Cosmetics, Redmond, WA	x
	Triheptanoin | SustOleo™ MCT	Inolex, Philadelphia, PA		x
	Heptyl undecylenate | LexFeel® Natural	Inolex, Philadelphia, PA		x
	Acetyl ethylhexyl polyhydroxystearate | PolyGel Emollient	Making Cosmetics, Redmond, WA		x
	Diisooctyl succinate | SustOleo™ DCS	Inolex, Philadelphia, PA		x
	Emblica Officinalis (amla) oil | Amla Oil	Making Cosmetics, Redmond, WA		x
Lipstick butter, skin conditioner, stick softening agent, glide enhancer	Petrolatum | Petroleum jelly	Making Cosmetics, Redmond, WA	x
	C10‐18 triglycerides | Lipocire™ A SG	Gattefosse, Paramus, NJ		x
	Butyrospermum parkii (shea) butter | Shea butter	Making Cosmetics, Redmond, WA		x
	Theobroma Cacao (Cocoa) Seed Butter | Cocoa butter	Making Cosmetics, Redmond, WA		x
	Jojoba Esters (and) Helianthus Annuus (Sunflower) seed wax (and) Acacia Decurrens flower (and) polyglycerin | Acticire® MB	Gattefosse, Paramus, NJ		x
Colour additive	Red 7 lake (and) Ricinus Communis (Castor) seed oil | N/A	Making Cosmetics, Redmond, WA	x	x
Antioxidant	Tocopherol | Vitamin E	Making Cosmetics, Redmond, WA	x	x

TABLE 2.

Cream ingredients screened for physicochemical properties in this study.

Function in product	INCI name | Trade name	Supplier (name and location)	Used in control product	Used in sustainable products
Humectant	Propylene glycol | Propylene glycol	Making Cosmetics, Redmond, WA	x
	Butylene glycol | Butylene glycol	Making Cosmetics, Redmond, WA		x
	Caprylyl glycol (and) ethylhexylglycerin | Caprylyl glycol EHG	Making Cosmetics, Redmond, WA		x
	1,2 Hexanediol | Lexgard® H	Inolex, Philadelphia, PA		x
	Glycerin | Glycerin	Making Cosmetics, Redmond, WA		x
Emollient	Mineral oil | Mineral oil	Making Cosmetics, Redmond, WA	x
	Simmondsia Chinensis (jojoba) seed oil | Jojoba oil	Arista Industries, Wilton, CT		x
	Vitis Vinifera (grape) seed oil | Grape seed oil	Arista Industries, Wilton, CT		x
	Prunus Armeniaca (apricot) kernel oil | Apricot kernel oil	Arista Industries, Wilton, CT		x
Emulsifier	Cetearyl alcohol (and) ceteth‐20 phosphate (and) dicetyl phosphate | Crodafos™ CS20A	Croda, Princeton, NJ	x
	Cetearyl olivate (and) sorbitan olivate | Olivem® 1000	Hallstar, Greensboro, NC		x
	Sorbitan stearate (and) sorbityl laurate | Arlacel™ LC	Croda, Princeton, NJ		x
Lipophilic thickener, co‐emulsifier	Cetyl alcohol | Cetyl alcohol	Making Cosmetics, Redmond, WA	x	x
Preservative	Propylene glycol (and) diazolidinyl urea (and) methyl paraben (and) propyl paraben | Paraben‐DU	Making Cosmetics, Redmond, WA	x	X

The purpose of including a control with conventional ingredients in this study was to demonstrate that sustainable improvements can be achieved in any formulation through deliberate ingredient choices. The control served as a baseline to highlight the contrast and illustrate the strategies cosmetic scientists can use to increase sustainability.

The ingredients' sustainability attributes are summarized in Table 3.

TABLE 3.

Sustainable ingredients in this study and their main attributes.

Ingredient category	INCI name	Sustainable attributes
Lipstick wax	Euphorbia Cerifera (candelilla) wax a [16]	Renewable, natural
	Copernicia Cerifera (carnauba) wax a [17]	Renewable, natural, organic
	NF white beeswax a [18]	Renewable, biodegradable
Lipstick emollient	Acetyl ethylhexyl polyhydroxystearate [19]	Renewable, biodegradable, vegan
	Diisooctyl succinate [20]	100% Natural, 100% USDA certified biobased content, Natural Origin Index: 1.0, Readily Biodegradable, COSMOS Approved, NSF/ANSI 305 Approved and Vegan
	Emblica Officinalis (amla) oil [21]	Naturally Derived
	Triheptanoin a [22]	100% USDA certified biobased content, Natural Origin Index: 1.0, Readily Biodegradable, COSMOS Approved, NSF/ANSI 305 Approved and Vegan
	Heptyl undecylenate a [23]	100% USDA certified biobased content, Natural Origin Index: 1.0, Readily Biodegradable, COSMOS Approved, NSF/ANSI 305 Approved and Vegan, 100% renewable feedstocks, one‐step esterification process, only byproduct of manufacturing is water
Lipstick butter	Butyrospermum parkii (shea) butter [24]	USDA Certified Organic, Vegan, Renewable, Cold Processed
	Theobroma Cacao (cocoa) seed butter [25]	USDA Certified Organic, Vegan, Renewable
	Jojoba Esters (and) Helianthus Annuus (Sunflower) seed wax (and) Acacia Decurrens flower (and) polyglycerin [26]	100% natural origin (ISO 16128), COSMOS approved, Readily biodegradable, Certified RSPO Mass Balance
	C10‐18 triglycerides a [27]	100% natural (ISO 16128), ECOCERT/COSMOS approved, Certified RSPO Segregated, Readily Biodegradable
Cream humectant	Caprylyl glycol (and) ethylhexylglycerin [28]	Manufactured by a catalytic Process, Vegan
	1,2 Hexanediol [29]	Readily Biodegradable, ChemForward Safer
	Glycerin [30]	Naturally derived, Vegan
	Butylene glycol a [31]	Manufactured by a catalytic Process
Cream emollient	Vitis Vinifera (Grape) seed oil [32]	Naturally derived
	Prunus Armeniaca (apricot) kernel oil [33]	Naturally derived
	Simmondsia Chinensis (fojoba) seed oil a [34]	Renewable, biodegradable
Cream emulsifier	Sorbitan stearate (and) sorbityl laurate [35]	ISO 16128—100% derived natural, Plant derived, COSMOS Approved
	Cetearyl olivate (and) sorbitan olivate a [36]	Biodegradable, Plant derived, COSMOS Approved

^a Used in the final formulas.

Methods

Physicochemical characterization of sustainable ingredients

In addition to identifying sustainability attributes of potential alternatives (Table 3), the sustainable ingredients were also screened for physicochemical characteristics depending on the physical form. The results of these tests allowed narrowing down the ingredient pool and deciding which ingredients to move forward.

For lipstick waxes and butters, melting points were searched in supplier literature and evaluated in‐house using differential scanning calorimetry analysis. A 65‐mg sample was weighed with an MT 5 microbalance (Mettler Toledo, Columbus, OH) and sealed in an aluminium crucible. A pinhole was created on the crucible lid to vent gas buildup. The analysis was performed at a 10°C/min ramp from 0 to 100°C, followed by cooling to 20°C, then heating again to 100°C at the same ramp using a DSC 822e instrument (Mettler Toledo, Columbus, OH) attached to a F25‐ME refrigerated/heating circulator (Julabo, Allentown, PA). Nitrogen gas was purged at a rate of 10 mL/min. TA Universal analysis software was used to obtain the scans.

Emollients for both the lipsticks and moisturizers and humectants for the creams were characterized by spreadability at 21°C and 55–60% relative humidity, following a test method developed previously by our research group [37].

Formulation of pigment dispersion for lipstick

The method described in our previous paper was followed [38].

Formulation of lipsticks

The method described in our previous paper was followed [38]. Two batches of each lipstick type were made, with ten lipsticks in each batch.

Each lipstick had the same base formula and formulation steps. The lipstick with conventional ingredients served as control (LC). There were three formulations in which one ingredient group, that is waxes (L1), emollients (L2) or butter (L3), was replaced with sustainable ingredients. Then, a formulation was created with all the ingredient groups replaced with sustainable alternatives (L4). The composition of the various lipsticks is summarized in Table 4.

TABLE 4.

Lipstick composition in this study.

Phase	INCI name	Ingredient amount (w/w %)
		LC	L1	L2	L3	L4
A	Microcrystalline wax	2.0	0.0	2.0	2.0	0.0
A	Ozokerite	4.5	0.0	4.5	4.5	0.0
A	Synthetic beeswax (and) synthetic wax (and) stearic acid	15.0	0.0	15.0	15.0	0.0
A	Beeswax	0.0	3.5	0.0	0.0	3.5
A	Euphorbia Cerifera (Candelilla) wax	0.0	12.0	0.0	0.0	12.0
A	Copernicia Cerifera (Carnauba) wax	0.0	5.0	0.0	0.0	5.0
A	Ethylhexyl palmitate	25.3	25.3	0.0	25.3	0.0
A	Caprylic/capric triglyceride	20.5	20.5	0.0	20.5	0.0
A	Triheptanoin	0.0	0.0	25.3	0.0	25.3
A	Heptyl undecylenate	0.0	0.0	20.5	0.0	20.5
A	Petrolatum	2.5	2.5	2.5	0.0	0.0
A	C10‐18 triglycerides	0.0	0.0	0.0	2.5	2.5
B	Red 7 lake (and) Ricinus Communis (castor) seed oil	30.0	30.0	30.0	30.0	30.0
C	Tocopherol	0.2	0.2	0.2	0.2	0.2

Abbreviations: L1, lipstick with waxes replaced; L2, lipstick with emollients replaced; L3, lipstick with butter replaced; L4, fully sustainable lipstick.

Physicochemical characterization of lipsticks

The pay‐off to fabric and friction was tested following our previously developed method [38] at 21°C with 55–60% relative humidity. Stability of lipsticks was monitored at room temperature (25°C) and 45°C in stability cabinets for 6 weeks. Samples were checked visually for any signs of physical instability, such as sweating and colour change, and tested instrumentally for hardness, pay‐off and friction at Weeks 1, 3 and 6.

Formulation of moisturizers

Each moisturizer had the same base formula and formulation steps. The oil‐in‐water (O/W) emulsion with conventional ingredients served as control. There were three formulations in which one ingredient group, that is humectant (M1), emollient (M2) or emulsifier (M3), was replaced with sustainable ingredients. Then, a formulation was created with all the ingredient groups replaced with sustainable alternatives (M4). The composition of the various moisturizers is summarized in Table 5.

TABLE 5.

Cream composition in this study.

Phase	INCI name	Ingredient amount (w/w %)
		MC	M1	M2	M3	M4
A	Water	75.0	75.0	75.0	75.0	75.0
A	Propylene glycol	5.0	0.0	5.0	5.0	0.0
A	Butylene glycol	0.0	5.0	0.0	0.0	5.0
B	Mineral oil	13.0	13.0	0.0	13.0	0.0
B	Simmondsia Chinensis (jojoba) seed oil	0.0	0.0	13.0	0.0	13.0
B	Cetearyl alcohol (and) ceteth‐20 phosphate (and) dicetyl phosphate	4.0	4.0	4.0	0.0	0.0
B	Cetearyl olivate (and) sorbitan olivate	0.0	0.0	0.0	4.0	4.0
B	Cetyl alcohol	2.0	2.0	2.0	2.0	2.0
C	Propylene glycol (and) diazolidinyl urea (and) methyl paraben (and) propyl paraben	1.0	1.0	1.0	1.0	1.0

Abbreviations: M1, moisturizer with humectant replaced; M2, moisturizer with emollient replaced; M3, moisturizer with emulsifier replaced; M4, fully sustainable moisturizer.

Physicochemical characterization of creams

Spreadability of the creams was tested with the same method described above for emollients and humectants at 21°C and 55–60% relative humidity.

Viscosity was tested with a Brookfield viscometer DV‐I (Brookfield Engineering Laboratories, Middleboro, MA, USA) and a concentric cylinder spindle in a small sample adapter. Tests were performed in triplicate at 21°C between 0 and 25 s⁻¹ shear rates.

Diameter (μm) of 30 droplets per each O/W cream was measured after staining the emulsions with a 10% Blue 1 dye solution and capturing images with a light microscope (AmScope type, Amscope, Irvine, California) at 10x magnification. This method was also used to confirm the type of emulsion.

Stability of the creams was monitored at 25°C and 45°C in stability cabinets for 6 weeks. Samples were checked visually for signs of physical instability, including separation and colour change, and tested instrumentally for viscosity and droplet size at Weeks 1, 3 and 6.

Data analysis

Differences in lipstick pay‐off, friction, hardness, melting point, cream spreadability and viscosity were evaluated statistically using one‐way ANOVA followed by Tukey's multiple comparison test using SPSS Statistics 21 software (IBM Armonk, NY). A p‐value less than 0.05 was taken as the minimal degree of statistical significance.

RESULTS

Physicochemical characterization of sustainable ingredients

Testing results for the conventional and sustainable ingredients during the screening phase are in Tables 6 and 7. The melting point measurements confirmed that the selected sustainable alternatives can proceed into the formulation phase. As for the butters, the butter blend and C10‐18 triglycerides were closest to the control's melting point peak. C10‐18 triglycerides were selected as the alternative since they were not a blend. Therefore, analyzing their effect on the lipstick properties would be simpler, and any change would only relate to one ingredient.

TABLE 6.

Physicochemical characteristics of waxes and butters for lipsticks.

Ingredient type	INCI name	Melting point range (°C) from literature
Wax	Microcrystalline wax a	79.4–86.7
	Ozokerite wax a	73.0–76.0
	Synthetic beeswax (and) synthetic wax (and) stearic acid a	72.5–82.5
	Beeswax	61.0–68.0
	Euphorbia Cerifera (candelilla) wax	68.5–72.5
	Copernicia Cerifera (carnauba) wax	80.0–85.0
Butter	Petroleum jelly a	36.0–40.0
	Shea butter	42.0–46.0
	Cocoa butter	34.0–38.0
	C10‐18 triglycerides	35.0–36.5
	Jojoba esters (and) Helianthus Annuus (sunflower) seed wax (and) Acacia Decurrens flower (and) polyglycerin	53.0–64.0

^a Control.

TABLE 7.

Physicochemical characteristics of emollients and humectants for lipsticks and moisturizers.

Ingredient type	INCI name	Firmness (g)	Stickiness (g)
Lipstick
Emollient	Ethylhexyl palmitate a	6.33 ± 1.68	9.98 ± 0.32
	Capric/caprylic triglyceride a	5.05 ± 0.20	9.52 ± 0.34
	Polygel emollient	5.24 ± 0.28	8.40 ± 0.41
	Heptyl undecylenate	5.59 ± 0.07	9.89 ± 0.27
	Triheptanoin	7.23 ± 1.29	11.06 ± 1.38
	Diisooctyl succinate	5.45 ± 0.16	10.20 ± 0.16
	Amla oil	5.33 ± 0.29	9.50 ± 0.42
Moisturizer
Humectant	Propylene glycol a	5.27 ± 0.12	8.84 ± 0.27
	Caprylyl glycol	5.32 ± 0.05	9.52 ± 0.26
	1,2 Hexanediol	6.42 ± 1.11	10.74 ± 0.94
	Glycerin	5.29 ± 0.22	7.67 ± 0.18
	Butylene glycol	5.27 ± 0.39	8.72 ± 0.15
Emollients	Mineral oil a	2.69 ± 0.28	6.70 ± 0.43
	Vitis Vinifera (Grape) seed oil	2.54 ± 0.21	7.21 ± 0.39
	Prunus Armeniaca (Apricot) kernel oil	2.54 ± 0.31	7.24 ± 0.30
	Simmondsia Chinensis (Jojoba) seed oil	2.76 ± 0.09	7.11 ± 0.28

^a Control.

The spreadability values, including firmness, that is positive force, and stickiness, that is negative force, of the alternative emollients were very similar to those of the conventional emollients. Heptyl undecylenate and triheptanoin were chosen for the lipsticks because they were readily biodegradable.

For moisturizer humectants, the firmness and stickiness values were similar. Butylene glycol was chosen as the sustainable alternative because its spreadability properties were the closest to propylene glycol. For moisturizer emollients, all firmness values were similar. Due to this, selection was based on stickiness. Golden jojoba oil was chosen because it is a sustainable crop and can be cold processed.

Physicochemical characterization of lipsticks

Appearance

Based on visual observation, all five lipsticks had a uniform red colour and glossy surface without visible imperfections.

Pay‐off and friction

Pay‐off refers to the amount of a product (measured as weight, unit: mg) deposited to a surface during regular application. In this study, the surface was a piece of fabric. Three cycles of deposition were used, where one cycle consisted of the texture analyser probe moving down and up once. Three cycles were chosen to mimic the way consumers apply lipsticks. Pay‐off was in the range of 27–63 mg at Week 1, with LC and L1‐L3 being similar, while L4 had a higher amount deposited onto the fabric (Figure 1a). The pay‐off values changed significantly (p < 0.05) over the 6‐week study for L4, while the rest of the sticks' pay‐off stayed similar to the Week 1 values.

FIGURE 1.

A. Pay‐off and B. friction results of lipsticks.

Friction refers to the resistance (measured as force, unit: g) to maintain a movement at a specific speed. Friction was measured during the three cycles of pay‐off testing. Average friction was the highest for L4 (80.2 g), followed by L3 (71.2 g), and the rest of the sticks' values were similar, in the range of 57.5–61.9 g. Week 3 and 6 followed similar trends to Week 1 friction. As Figure 1b shows, friction was the highest during Cycle 1 for all sticks, which aligned with our expectations and previous results. When the stick is moved on the substrate the first time, there is more friction between the stick and substrate, but the second and third cycles are done on the product layer created during cycle 1, assisting with glide and consequently lowering friction.

Needle penetration test

Hardness of a lipstick refers to firmness and the resistance to deformation. In this study, hardness was measured by the amount of force (unit: g) needed to penetrate the stick with a metal needle to a certain depth. During Week 1, all lipsticks had a comparable hardness in the range of 136.3–184.5 g, without significant differences (p < 0.05). Hardness remained consistent over the 6 weeks within each lipstick group (Figure 2).

FIGURE 2.

Hardness results of lipsticks.

Melting point

Melting point refers to the temperature (unit:°C) where a solid ingredient, such as a stick, becomes liquid. Waxy materials often melt over a range of temperatures, instead of a single point. In this study, the peak of the melting range is reported. The average melting peak of each lipstick type is shown in Table 8. There was no statistically significant difference (p < 0.05) in the melting points, indicating similar quality even when the ingredients most significantly influencing the melting behaviour of the sticks, that is waxes, were replaced. This is an important quality of any stick product and contributes to stability in elevated environments.

TABLE 8.

Melting peak of lipsticks (results are shown as average ± standard deviation).

Lipstick	Melting peak (°C)
LC	43.79 ± 2.35
L1	42.82 ± 2.97
L2	43.07 ± 1.78
L3	46.21 ± 3.20
L4	48.30 ± 6.97

L4 had the highest melting point and pay‐off during Week 1, while its hardness was similar to the other sticks. This demonstrates that replacing conventional ingredients with more sustainable choices and maintaining product quality and performance is possible. Higher pay‐off may be a bonus, positive property as consumers can get more product applied to the lips and possibly a more intense colour, depending on the colour additives in the stick, with the same number of strokes, which could translate into the product lasting longer. Friction did not show a notable trend over the 6 weeks and overall, all the products had a similar average friction.

It should be noted that arriving at the wax blend ratio used in the stick took multiple experiments, mostly relying on the melting point of the individual waxes. While this may take some time for a formulator at the bench, it is possible to create a similar consistency.

No specific trends were observed when comparing friction, hardness and pay‐off (Figure 3). It may be assumed that waxes drive the friction and hardness values of sticks, and the two values should move in the same direction. However, no link between any of these three parameters was observed in this study.

FIGURE 3.

Comparison of all lipstick results to identify trends.

Stability

No change in colour, product shape or consistency was observed visually over the 6 weeks at either temperature.

Overall summary of lipstick results

From all the characterization techniques used, pay‐off and friction were the most different among the lipsticks, with M4, the lipstick containing the sustainable ingredients, having the highest average friction and pay‐off at Week 1. While the differences were considerable, these parameters can be fine‐tuned by adjusting the ratio of ingredients in the formula.

Physicochemical characterization of moisturizers

Appearance

Based on visual observation, all five creams were opaque with a smooth texture and glossy appearance. MC, M1 and M2 were white, while M3 and M4 were pale yellow due to the change in emollients (jojoba oil compared to mineral oil).

Spreadability

Spreadability refers to the ease of spreading a product on the skin. In this study, spreadability was measured by applying force (unit: g) via an acrylic probe and assessing the amount of force needed to penetrate the product to a certain depth. When measuring spreadability, two parameters were closely evaluated, including firmness, that is the positive maximum force needed to penetrate the sample, and stickiness, that is the negative maximum force measured when withdrawing from the sample.

The differences were larger in firmness and more similar in stickiness. M2 had the highest firmness throughout the 6 weeks (Figure 4). The difference between M1 and M2 was the humectants and emollients used, which had very similar firmness individually (Table 7). Interaction with the other ingredients, including the emulsifier, could have contributed to this higher firmness.MC, M1 and M2 versus M3 and M4 had different emulsifying systems, leading to markedly different firmness values. M2 had the highest, but not significantly different, stickiness among the five creams.

FIGURE 4.

Firmness and stickiness of the moisturizers during the 6‐week study.

Viscosity

Viscosity refers to the resistance to flow (unit: cP) due to internal friction in a material or product. In this study, a viscometer was used with a cylinder spindle. All moisturizers had shear thinning behaviour, which is typical for personal care creams. Viscosity ranged between 8650 and 16 250 cPs at 10 rpm during Week 1 and remained consistent during the following 6 weeks.

Droplet size

Droplet size refers to the diameter (unit: μm) of the internal phase of an emulsion. In this study, a light microscope was used to capture images of the emulsions and diameter was measured using the microscope's software. The droplet size was typical for macroemulsions; it ranged from 21 to 38 μm and stayed between 21 and 32 during the 6 weeks, indicating acceptable stability of the emulsions. The images confirmed that the emulsions were O/W type, as the water‐soluble Blue 1 dye was located in the outer phase of the creams.

Stability

Over the 6 weeks, no creams showed signs of physical separation, bacterial growth or discoloration at either temperature, based on visual observation.

Overall summary of moisturizer results

Spreadability had the largest differences, mostly due to the different emulsifier systems, as expected. Emulsifiers influence product stability and contribute to product consistency and skin feel. This should be considered if the emulsifier(s) need to be changed in a product.

CONCLUSION

Ideally, little to no differences in quality, performance and stability should be seen when replacing ingredients in products. Our goal was to evaluate how a one‐on‐one change affects lipstick quality, stability and performance, not how close we can get these parameters to the control.

While some tools have been developed, such as the Excel sheet by the Research Institute for Medicines as mentioned in the introduction, not all the information is available to formulation chemists to utilize these tools. In this study, not all information was available to us from the suppliers to generate results in the Excel sheet. Sustainability calculation tools will need to consider the type and amount of information available for formulation chemists; otherwise, the tools cannot be utilized as designed.

These case studies serve as an example for formulation chemists as approaches to systematically selecting and replacing conventional ingredients with more sustainable choices were showcased. As demonstrated, incorporating sustainable ingredients can be challenging, but having quality products while being more environmentally friendly is possible. If it is an expectation that a product is reformulated to be more sustainable and it should also match the original, that is less sustainable product's quality and performance characteristics, more work needs to be done to finetune the quality and performance parameters, including skin feel of the product.

CONFLICT OF INTEREST STATEMENT

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Spaulding A, Baki G. Sustainable cosmetic ingredient alternatives to replace conventional ingredients: Case studies in moisturizers and lipsticks. Int J Cosmet Sci. 2026;48:83–96. 10.1111/ics.70020

DATA AVAILABILITY STATEMENT

The data that support the findings of this study are available from the corresponding author upon reasonable request.