## 1 Introduction  
Hydration is a fundamental need in skin care all over the world as evidenced by regular reviews on moisturizing agents, both for cosmetic and therapeutic uses [1, 2, 3]. Water content, ideally between 10% and 15%, is essential to maintain skin health, with optimized barrier function. Skin moisturization also supports mechanical properties of the skin (plasticity) and a smooth surface appearance [4]. Some areas of the body such as the face and extremities are more likely to dry out; localized, drier facial skin was also found on subjects presenting with a \"normal skin\" condition, without visible signs of roughness [5, 6]. Aging also increases the propensity for skin dryness, with disparities depending on the body area [7, 8, 9]. Environmental factors (e.g., climatic conditions) additionally impact skin health. While climatic change and the consequences of global warming on humans are a matter of debate, excessive temperature and reduction in relative humidity caused by the land warming faster than the sea, at least during transient extreme climatic events, would result in more people with dry skin and an increased need for moisturizing care [10]. This background is driving the development of new active ingredients, targeting different levels of biological moisturization mechanisms and multifunctional ingredients to ensure long-term biological efficacy. In parallel, increasing consumer demands for immediate instant efficacy have been observed in recent decades. The advent of social media and selfies reinforced these expectations of immediacy. Beyond its role to deliver the active ingredient, the formulated vehicle (also called the excipient) can bring instant effects at the skin surface [11]. Excipients can have visible actions, such as blurring lines, or perceivable effects, such as softened-moisturized-replenished skin or a sensation of comfort. In some applications, such as daily body moisturizers, formulations often do not contain any moisturizing active ingredient [10], especially when affordability is becoming an issue, so excipients should be selected carefully. Containing both oil and water, emulsions are the most used vehicles when looking for moisturization [3; 11; 12]. The emulsion composition brings three mechanisms into play: occlusive film-forming, emollience (i.e., improved skin plasticity and texture typically brought by oils and hydrophobic compounds) and attracting/holding water in the skin through humectant (hygroscopic) ingredients. While water-in-oil emulsions are sometimes used for very dry skins, oil-in-water (O/W) emulsions are the preferred versatile formulations for moisturization purposes. The wide variety of achievable textures make it possible to adapt for any skin type, any functionality (e.g., sun protection, make-up) and any application area (e.g., face care, body care). Moreover, the adjustable external aqueous phase content, resulting in varying degrees of freshness on contact, makes it suitable for all types of climates, including hot and humid regions [12]. Multiple surfactant structures are available to stabilize these O/W emulsions. Among classes of non-ionic environmentally friendly compounds, alkyl polyglucosides (APG) have achieved a dominant position in the last two decades. In Europe, APGs accounted for around a 23% share of the global sugar-based surfactants market at the end of 2021 [13]. APGs are glucolipid molecules based on renewable glucose and fatty alcohol. Those with short and medium-length fatty chains (e.g., C8-C10, C12-C16) exhibit foaming properties, and longer C16-C18 chains have an emulsifying capacity and are widely used in the cosmetic industry. An O/W emulsifier based on C16-C18 alcohol (INCI: cetearyl alcohol (and) cetearyl glucoside) was found to create both lamellar liquid crystalline bilayers around the oil droplets, visualized as a birefringent Maltese cross by polarized light microscopy, and lamellar gel networks built in the continuous aqueous phase, substantiated by transmission electron microscopy (TEM) observation.