What is the "glow"?
Don’t you sometimes wonder when you use a new product and wake up with a glow the next day but don’t really know what that “glow” is? You do the same routine the next day, but the glow isn’t as ...glowy. You know it when you see it, but you can’t put a finger on it, and you don’t know exactly what to do to get it again.
Sometimes you see it on other people’s faces where they look more radiant and healthy, but there isn’t a single explanation why. Interestingly, some studies propose that you can tell if someone is rich or healthy just by looking at them. An old wives tale even says that you can tell if a pregnant woman is carrying a boy or a girl just by the radiance on their face.
In recent years, the popularity of dewy skin skyrocketed, thanks to Korean skincare. It looks like your face is oily but seemingly healthier. The look is achieved through layers upon layers of hydrating products, resulting in a shiny but radiant look. Again, you can’t really pinpoint the exact factor, but that radiance is something to behold. However, what is it exactly, and how can we achieve it?
Well, apparently, our brain takes into consideration various optical signals when we see a face. It then sums up all these signals to determine if a face is radiant, oily, matte etc. The science is a bit complicated on this one, and scientists have studied it for a long time, even coming up with complicated algorithms for it!
Several studies have shown that the radiance of our skin dictates how old, tired and healthy we look. The good news is that we can optimize for a more radiant look by understanding how light works and interacts with our skin. Here’s the summary:
When light hits the skin, most of it penetrates to some degree and interacts with the skin layers. Some get absorbed, and some bounces back to the surface in a more diffused and subtle way. This Diffuse Radiance comprises about 93-96% of what we see. The other part bounces off immediately after interacting with anything on the skin surface. This Spectral Radiance only comprises 4-7% of the light we see, but this doesn’t mean it’s less critical.
In fact, our brain puts a heavier weight on Spectral Radiance than on Diffuse Radiance. Studies show that skin with low Spectral Radiance (matte skin) looks older and less healthy than skin with higher Spectral Radiance. This means that mattifying your skin can make you look a few years older. In ranking how healthy faces look, participants of a study ranked matte skin to seem the least healthy, followed by oily skin, with radiant/dewy skin the healthiest. Okay, but what is the difference between Oily skin and Radiant skin?
How is Radiant/Dewy skin different from Oily skin?
Oily skin
Oily skin has a more focused light because of abnormally high levels of Spectral Radiance. This means that in shiny skin there is a layer of sebum on the surface which causes more light to immediately bounce back - hence the glossiness.
Aside from sebum, there are other factors that can make your skin appear Oily without oil. If you look at your skin, you'll notice some really fine criss-cross lines that have even finer lines within them. When light bounces of the surface, these lines slightly diffuse Spectral light. However, as we age, our skin starts losing these lines and it becomes more flat. Light that bounces off flat skin is more focused, making aged skin appear thinner and shinier.
Dewy/Radiant skin
Radiant skin and Oily skin both have high Spectral Radiance, which means they both appear glossy. The difference is that Oily skin has a higher Spectral Radiance than Radiant skin AND that Radiant skin has a high Diffuse radiance compared to Oily skin with only low amounts. This means that Radiant skin doesn't only shine from the surface, but also glows from within. 
How to Achieve Radiant skin
Obviously the goal is to have glowing/ radiant/ dewy skin. What we need to do is to think about the two aspects discussed above and optimize the factors that affect them.
Spectral Radiance
Our goal here is to optimize spectral radiance to a higher level. Too high of spectral radiance would make your face too shiny, too low would make it look dull. Our goal is to keep it at high but not too high as we want some shine to contribute to the radiant look. Here’s what you can do:
Optimizing Spectral Radiance
Step 1: Optimize surface oils
If you have really oily skin, you need to lower sebum on the surface of the skin. You don’t need to resort to absolutely mattifying your skin. Studies show that matte skin looks dull, sickly and a few years older than radiant or even oily skin. Here’s what you can do:
On the other hand if your skin looks dull and dry and needs a bit of shine:
Finding the perfect balance can be tricky but opting for a more shiny look is better. People with oily skin are at an advantage here.
Step 2: Even out the skin
Maintain those Fine Wrinkles. When we talk about fine wrinkles here, we’re talking about the primary and secondary lines on your skin if you zoom really close. These are not the same as the fine wrinkles associated with aged skin. (I know the scientists should have not named them as such as it is confusing. Those lines actually have names but I can't remember their names and I can't find the journal that I've read. Email us if you find it.) Those lines actually help diffuse the light that bounces off of your skin. As you get older, those lines start to disappear and your skin becomes flat causing it to look shinier. Here’s what you can do:
Yes you read that right. Some products have some mild exfoliative property that causes your Stratum Dysjunctum (loose upper layers of Stratum Corneum) to loosen up and appear more opalescent. This is glow is not permanent and goes away when your skin gets used to the product.
Step 3: Artificial Soft Focus
Product wise, there are newer technologies that would artificially optimize the spectral radiance by giving it a “soft-focus” look. These can be silicone (Polysilicone-11, Polymethylsilsesquioxane and Silicone Crosspolymers), silica and natural polymers (cellulose, certain starches). These are not the same as mattifying agents. The idea is that they:
Diffuse Radiance
Now for diffuse radiance. Our goal here is to increase diffuse radiance as low levels make our skin look really dull. Here what you can do:
Optimizing Diffuse Radiance
Step 1: Reduce Water Loss
Reduce water loss to increase water content in the skin. (Note: you don't hydrate the skin, the skin hydrates itself. You just need to prevent it from losing too much) Improving the barrier is the ultimate key to a hydrated skin. High water content of the skin is correlated with a higher diffuse radiance. This is possibly due to water acting as a medium for light scattering.
Step 2: Even out Pigmentation
Even pigmentation. Prevent hyperpigmentation from happening in the first place:
Step 3: Protect your basal layer
Dermoepidermal Junction + Collagen. These structures are in the lower parts of the skin. Collagen is one of the major light scattering points in the skin so having even and organized collagen is important to keeping light scattering even. The Dermoepidermal Junction is the junction where your epidermis and dermis meets. This is also where your melanocytes lie, hence where most of pigment production occurs. This is why it is called the melanin layer. (Refer back to Figure 1) A lot of light is absorbed in this layer. Having a uniform layer of DEJ helps maintain the eveness of light scattering and therefore radiance in the skin.
Step 4: Eat your Veggies
Hemoglobin Content. (The red pigment in blood and skin) You can’t really do much about this unless you are anemic (Eat your veggies?). Newer studies have found that there is an optimum amount of Chromophores (Melanin, Hemoglobin) that makes the skin radiant. Not to much but not too little (Goldilocks)
How the brain sums everything up
Interestingly, how we perceive radiance is quite complex. When we look at a face, our brain sums up all the factors mentioned above and looks at the level of spectral radiance and diffuse radiance. A radiant look isn’t really about a specific color or brightness of the skin. It is instead the summation of various factors. It’s as if your brain gives a score for hyperpigmentation, hemoglobin etc., to determine if that face is glowing.
You may notice that some of these factors are immediate, some take time, and some can never change. It would be best if you had a balance of all of these factors to achieve that ultimate radiant look. You can’t just focus on exfoliation as that will affect only a part of radiance, and it is usually temporary. You can temporarily have slightly glowing skin by Exfoliating+Hydrating+Using Soft Focus products. However, this artificial glow will never be complete without slowly targeting those factors affecting diffuse radiance.
The important thing here is prevention. Preventing damage, preventing inflammation, preventing spots, preventing damage to DEJ. I know its anti-climactic, it's not something flashy, no magic powders or potions, nothing exciting, but Prevention really is the key.
An Important Note on Lighting
Lighting is one of the major factors in the radiance of the skin. There are studies that even looked into the effect of lighting on getting the perfect radiant look and its not just trial and error. They did algorithms and complex computation to figure out the perfect way to light a face. In the industry it is the same, they need tons of light equipment, scrims, etc just to make it look effortless. Even those pictures on Insta where they look like they just woke up, those took so much effort to get the perfect lighting and angle. The point is, fluorescent light sucks, and don't compare your skin to someone's insta pics.
tl;dr
In Summary, here’s what you need to do to get the ultimate radiant skin:
References:
- Bjornsdottir, R. T., & Rule, N. O. (2017). The visibility of social class from facial cues. Journal of personality and social psychology, 113(4), 530–546. https://doi.org/10.1037/pspa0000091
- Axelsson, J., Sundelin, T., Olsson, M. J., Sorjonen, K., Axelsson, C., Lasselin, J., & Lekander, M. (2018). Identification of acutely sick people and facial cues of sickness. Proceedings. Biological sciences, 285(1870), 20172430. https://doi.org/10.1098/rspb.2017.2430
- Igarashi, T., Nishino, K., Nayar, S., (2005), The Appearance of Human Skin. Technical Report: CUCS-024-05, Columbia University