Everyone is Talking About: Glass Skin
Glass skin and glass hair are massive news at the moment, with many cosmetic ingredients and products specifically being developed to give a glossy, almost reflective, complexion. But what is glass skin? How do you get it? And what’s the science behind it? This short article will answer all these questions, as well as consider if there are any risks behind this celebrity-endorsed beauty trend.
What is glass skin?
Glass skin is a beauty trend that originated in South Korea, and focusses on achieving a clear complexion with no imperfections. The idea is that skin looks like it’s in optimal health, oozing radiance, and is deeply hydrated, resulting in an almost dewy look. While this trend focusses on the importance of skin hydration, overall appearance is also a key feature, and when pursuing glass skin, pores should not be visible. However, while good levels of hydration are clearly important and necessary for a healthy skin and body, the absence of pores is not necessarily a realistic target; pores on the skin’s surface are essential structures that are vital for the skin to function properly. Elimination of pores is therefore not an option.
The importance of pores
Pores are tiny openings on the skin’s surface, and there are two primary types: those that release oil (pilosebaceous units) and those that release sweat (eccrine glands). While production of sweat is key for thermal regulation of the body, the production of oil, or sebum, is vital for healthy skin. Sebum is an oily, lipid-rich substance lubricates and protects the skin’s surface, as well as providing a protective barrier to prevent moisture loss. While pores are usually very small, and often barely visible, they can become more noticeable if excess sebum is produced, as this can lead to larger pores and blackhead formation, skin elasticity is reduced, for example due to age or dehydration, or the skin is subjected to aggressive cleansing, which can result in the skin being aggravated therefore producing more sebum, resulting in pores that can appear larger.
How do I get it?
Healthy, radiant skin is often associated with hydration, therefore ensuring that you’re drinking enough is a good place to start. However, water can also be added to the skin from external sources, hydrating skin from the outside rather than from within the body. There are many cosmetic products and treatments available that can do this, with many containing humectants (substances that hold water and keep surfaces moist), such as glycerin or hyaluronic acid. During product development it may be necessary for the ability of a product to hydrate skin to be quantified. At TRI we offer several approaches to achieve this, including IR or Raman spectroscopy and electrical capacitance. Other tests that may be relevant for investigating the effect of any skin treatments may include the measurement of skin natural moisturizing factor (NMF) levels and the structure and integrity of the skin’s lipid barrier.
Glass skin: beyond hydration
However, there are other ways of giving the illusion of healthy, hydrated skin beyond the addition of water. The use of ingredients that add a layer of product to cover the skin’s surface, such as foundations or tinted moisturizers, can be useful as these items often contain pigments that smooth out skin blemishes and give an even skin tone. Finally, the use of exfoliants and scrubs to remove dead skin cells can help reduce skin dullness and give a more even complexion.
The science part
One of the key aspects of glass skin is the radiance of a complexion, which is a measure of how well skin reflects light. Skin that reflects light well is smooth and unblemished, and can be described as ‘lustrous’. Luster is a measure of the shininess of an object when it’s placed in the path of a beam of light. Objects that have high luster reflect the light from the surface effectively. However, just reflecting the light isn’t enough; it needs to be reflected in a particular way. There are two types of reflectance: specular reflectance and diffuse reflectance, Figure 1.
Figure 1: Specular reflection vs diffuse reflection. Image generated by Google AI.
Specular reflectance is when light is reflected as it is in a mirror i.e. the reflected ray of light emerges at the same angle as it enters the surface. A good example of this is light off a puddle.
Diffuse reflectance is where incident light is scattered at many angles, such as when light is reflected off a stone statue. Diffuse reflectance makes items appear dull, or muted.
When there are dead skin cells on the skin’s surface, diffuse reflectance can dominate: the skin cells reflect light, but the light is scattered in all directions causing skin to appear dull. However, when these cells are removed and the skin surface is smoother, more specular reflectance can occur, leading to increased luster and the perception of radiance. Specular reflectance of the skin can be achieved through two principle means: the use of products and by increasing skin hydration.
The application of products to the skin surface, especially products that contain light-reflecting pigments such as mica or fluorphlogopite, is the first method discussed. These products both physically smooth the surface of the skin by forming a layer or film, and the pigments present in them increase the levels of specular reflectance (rather than diffuse reflectance), which means skin looks more lustrous, giving the impression of radiance and health.
Increased skin hydration also increases the proportion of specular reflectance, with skin that is hydrated tending to be plumper and therefore providing a smoother surface for light to reflect from. While many cosmetic items contain water, often as the main ingredient, there are other additives that can aid water retention and draw water into the stratum corneum - the outermost layer of the skin. These materials create a barrier between the body and the environment, reducing the rate of water loss and ensuring that skin stays hydrated (and therefore plumper) for longer. Key additives for adding water to the skin include humectants, occlusives, and emollients.
Humectants
Humectants are molecules that can bind to water, usually because they contain chemical functional groups that can interact with water molecules through hydrogen bonding. Water is provided either through the product itself, or is drawn from deeper in the dermis. Examples of humectants include glycerin, ectoin and hyaluronic acid. Skin also produces its own humectant, natural moisturizing factor (NMF), which helps the skin maintain water and prevents transepidermal water loss (TEWL).
Occlusives
Occlusives can form a physical barrier on the skin’s surface, slowing the rate of TEWL. These materials don’t add hydration to skin themselves, but by slowing evaporation they preserve water already present. Common occlusives include ceramides (which are naturally present in the skin already), petrolatum, dimethicone, beeswax, and lanolin.
Emollients
Emollients fill the microscopic gaps between cells in the stratum corneum, improving the smoothness at a microscopic level and reducing roughness. The fact that the skin’s surface has become smoother therefore improves the specular reflectance profile. Common emollients include plant oils, squalane, fatty alcohols like cetearyl alcohol, and shea butter.
Bringing it all together
Glass skin is a skincare trend based on skin looking lustrous and healthy, which is all related to the ability of the skin surface to reflect light like a mirror: specular reflectance. Keeping skin hydrated by using products containing agents with hydrating properties, by drinking water and hydrating from within, or by using cosmetic items with light-reflecting additives can enhance the amount of specular reflectance therefore giving the impression of glass skin.
TRI Princeton can provide support and help for claims relating to glass skin, and any other current trends. Reach out to our team today!
