Where Does All That Product Go?
These past couple of weeks I've been learning about the fascinating subject of product penetration. It only makes sense that a cosmetic formulator should understand somewhat how human skin functions and how product penetrates the skin. Turns out there's more to it than having a great moisturizer and assuming it will do great things for your skin.
Did you know it's actually a myth that 60% of everything you apply ends up in your bloodstream?
To begin, the top layer of skin, the layer we see when we look in the mirror, is called the stratum corneum. And it is very effective at doing its job as protective barrier between the environment and the layers of skin beneath. It defends the body from penetration of foreign matter and toxins, and fights against sun-damage. As I mentioned in my last post, the stratum corneum also is made up of rows of corneocytes (essentially dead skin cells). These bond together forming the impermeability of the skin. Lipids within the skin are secreted which seal the bonded corneocytes, preventing moisture loss while keeping skin soft and plump. So really the outermost layer of our skin is the trickiest for product to get past. Isn't our skin amazing?! It's truly incredible that any substance should penetrate the skin!
Dermal penetration is different for everyone and depends on various factors. A few of these include warmth of the skin, men versus women's skin (as men's skin is thicker), hydration of the individual's skin, age, and amount of product applied.
For anyone with a skin care routine, this information can be very helpful in knowing what order to apply products. As a rule of thumb, water based products are applied first to hydrate the skin. Examples are mists and toners. Water based serums can be applied here too. These products contain active ingredients that penetrate deep into the skin's layers to rebuild and nourish at a cellular level. Day/night creams or moisturizers are applied next, as they are an emulsion of water and oil based ingredients. The former to hydrate and deliver actives, and the latter to seal in that hydration and protect. The last product to be applied in your skin ritual is any oil or butter based product, such as a balm or face oil. Occlusive products like these do not penetrate past the first couple cell layers of the stratum corneum. And we don't want them to, as their job is to nourish and protect; form a sort of seal.
Of course, there's no need to use all of these products and steps mentioned. Each of us has different skin needs and skin types. And skin conditions may change according to the time of year or stage of life we are in. The important thing is when going about your skin ritual is to apply your products in the correct order so they can do their job effectively.
I have a newfound respect for cosmetic formulators. Although I am in the botanical/natural/organic/high-quality-ingredients/small batch/ skin care formulator camp, I have an admiration for all cosmetic formulators in the beauty industry. Ingredients get such a bad rap now days. Especially if upon reading the label, one can't pronounce what they are reading (much less know what that ingredient is.) Of course the ingredients could very well be listed in their Latin names as is the global standard, which makes understanding them hard enough. But even if it's in plain English, there very well may be ingredients which are hard to pronounce but have a very good reason for being there. (To note: of course you should do your homework as there are plenty of harmful ingredients in products today. My point being, that just because an ingredient is long or hard to read doesn't mean we shouldn't use it).
Formulators have so many details to think about. What actives do I want to deliver and to what part of the skin? How are they going to get their? Is their dosage enough to be effective while still maintaining the integrity of the skin? What delivery system will be used to get said actives to their goal? Is their molecular size too big or too small to penetrate? What other functions do I want this product to have? Cosmetic formulators must also think about the ph of the product in relation to the skin, the stability of the product, and whether it will be sensitive to sunlight. If an ingredient's molecular size is too big, it's never going to get past that first layer of skin. Or sometimes an ingredient may bind onto the skin's surface by other ingredients. Formulators also have to consider the passage of ingredients, as there are only three ways an ingredient can penetrate. One, through the lipids that are in between the corneocytes of the stratum corneum. Two, going right on through the cells themselves. Or three, taking shunt route, that is going through hair follicles and sweat glands.
We are blessed to be living in an age when so many fantastic beauty products are available to us. Feasting my mind on the intricacies our how our skin functions directs my soul in awe of Creator God. Beginning to understand product penetration is like opening up the shade to let the sunlight in, if you will. I anticipate using this knowledge to better my skills as a hobbiest formulator. I hope you've found a nugget or two for yourself as well.
Until next time . . .