Do you need to moisturise or hydrate - what's the difference?
I've always had very sensitve and dry skin, and during my teenage years I had patches of red, dry, sore skin over my face and neck. Because of this I've used products on my skin since my teenage years.
Over the years I've tried a whole range of different products, with varying reactions or not, and with varying degrees of success with keeping my dry skin under control.
For many years I thought that a moisturiser and a hydrator are the same things with an interchangeable name. However, this is not the case, and they do, in fact, do very different things........
So, what's the difference?
First, I think it's important to talk a little bit about skin structure.
The top layer is called the epidermis, and this subdivided into 4 layers, with the deepest layer being the stratum basale.
New skin cells are born in the stratum basale, and are then pushed up through the other layers as more new cells are born. During this journey through the layers lipds are released into the cell spaces to produce the skins own natural moistusing factor (NMF).
Healthy skin is able to produce sufficient lipid cells that communicate with the sebaceous galnds to produce sebum, which keeps the surface of the skin coated with sufficient sebem to keep the skin well hydrated.
If this process becomes interrupted in some way then the skin loses hydration and becomes dry and flaky.
Moisturisers and hydrators both serve to help keep the skin hydrated but act in very different ways....
Moisturisers
The primary role of a moisturiser is to prevent evapouration of water through the skins pores; this is called transepidermal water loss.
They do this by forming a protective barrier over the top of the skin to prevent water loss.
Although there are some more specialised moisturisers available, most moisturisers contain one of three main types of ingredient:
1) Occlusive agents (water repelling) - ingredients such as petrolatum, waxes, oils, and silicones (dimethicone, cocoa butter, and allantoin). These provide a physical barrier over the surface of the skin to reduce water loss. These types of products can feel heavy on the skin, and as such are often mixed with emolients.
2) Emolients - ingredients are esters, oils and butters and there are too many to mention but a list can be found here. The purpose of an emolient is to provide some occlusivity, but mainly to smooth the flaking cells and improve the appearance of the skin. The feel of an emolient on the skin is dependent on the ingredient used.
Hydrators
The main purpose of a hydrator is increase the moisture content within the skin. They do this by using hygroscopic (water attracting) humectants.
1) Humectants (water attracting) - ingredients such as glycerin, urea, hyaluronic acid and pyrrolidone carboxylic acid (PCA). These draw water from the dermis and keep it locked into the layers of the epidermis. They also draw water from the atmosphere and lock it onto the surface of the skin. These types of products can feel tacky on the skin.
So, what does this all mean?
You might find some moisturisers that have humectants built in. The problem with this is that, dependant on the skin's needs, they don't provide sufficient hydration because they're not strong enough in this medium.
If you're only using a moisturiser you might be finding that you need to keep applying it because it's only addressing the surface issue rather than the root cause of the problem.
Ideally, you need to use both a hydrator and a moisturiser so that you have a two-pronged approach.
It's recommended that you apply the hydrator first and the moisturiser over the top, although their has been a question rasied about whether the moisturiser would then prevent water absorption from the atmosphere becasue the moisturiser forms a protective physical barrier over the top.
My advice would be to use both, but you might need to have a play with how you apply your products to get the best results for your skin.
Incidentally, I now use a
hydrator first and then a tinted moisturiser over the top once the hydrator's soaked in a bit. I've definitely noticed that my skin is less sensitive, and looks healthier, plumper and brighter. I now don't have to use a foundation base to soak up the excess oil on my T-zone, and I don't have cheeks that feel so dry they might crack!
Message me here for more information and advice.
References
Barclay-Nichols (2009) Better crafting through chemistry: Humectants. (online) at swiftcraftymonkey.blogspot.co.uk. [Accessed 09/07/2017].
Barclay-Nichols S (2012) Question: What's the difference between moisturizing and hydrating? (online) at swiftcraftymonkey.blogspot.co.uk [Accessed 09/07/2017].
Dobos K (2017) How do skin moistuizers work? (online) at chemistscorner.com [Accessed 09/07/2017].
Savage J (2017) Hydrating vs moisturizing skin care. (online) at www.beenaturals.com [Accessed 09/07/2017].
Tortora GJ, Derrickson B (2012) Principles of anatomy and physiology. 13th ed. Wiley: New Jersey.
Unknown (2017) The skin cycle. (online at www.skinauthority.com) [Accessed 25/05/2017].