UV Sheer Broad‐Spectrum SPF 50
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EltaMD UV Sheer Broad‐Spectrum SPF 50Ingredients explained
An oil-soluble chemical sunscreen agent that protects skin in the UVB and somewhat in the UVA II range with a peak absorption of 304 nm. Its protection is not strong enough on its own but it is quite photostable (loses 10% of SPF protection in 95 mins) and is often used to stabilize other photo-unstable UV-filters, for example, Avobenzone. It is also often used to improve the water resistance of the products.
Octocrylene's safety profile is generally quite good, though a review study in Contact Dermatitis reports an "increasing number of patients with photo contact allergy to octocrylene." Mainly adults with ketoprofen-sensitivity and children with sensitive skin are affected, so if you have a small kid, it is probably better to use octocrylene-free sunscreens.
When it comes to sunscreen agents, Zinc Oxide is pretty much in a league of its own. It's a physical (or inorganic) sunscreen that has a lot in common with fellow inorganic sunscreen Titanium Dioxide (TiO2) but a couple of things make it superior even to TiO2.
If physical sunscreens don't tell you anything, go ahead and read about the basics here. Most of what we wrote about Titanium Dioxide is also true for Zinc Oxide so we will focus here on the differences.
The first main difference is that while TiO2 gives a nice broad spectrum protection, Zinc Oxide has an even nicer and even broader spectrum protection. It protects against UVB, UVA II, and UVA I almost uniformly, and is considered to be the broadest range sunscreen available today.
It's also highly stable and non-irritating. So much so that Zinc Oxide also counts as a skin protectant and anti-irritant. It's also often used to treat skin irritations such as diaper rash.
As for the disadvantages, Zinc Oxide is also not cosmetically elegant. It leaves a disturbing whitish tint on the skin, although, according to a 2000 research paper by Dr. Pinnell, it's slightly less white than TiO2. Still, it's white and disturbing enough to use Zinc Oxide nanoparticles more and more often.
We wrote more about nanoparticles and the concerns around them here, but the gist is that if nanoparticles were absorbed into the skin that would be a reason for legitimate health concerns. But luckily, so far research shows that sunscreen nanoparticles are not absorbed but remain on the surface of the skin or in the uppermost (dead) layer of the skin. This seems to be true even if the skin is damaged, for example, sunburnt.
All in all, if you've found a Zinc Oxide sunscreen that you are happy to use every single day, that's fantastic and we suggest you stick with it. It's definitely one of the best, or probably even the best option out there for sun protection available worldwide.
Good old water, aka H2O. The most common skincare ingredient of all. You can usually find it right in the very first spot of the ingredient list, meaning it’s the biggest thing out of all the stuff that makes up the product.
It’s mainly a solvent for ingredients that do not like to dissolve in oils but rather in water.
Once inside the skin, it hydrates, but not from the outside - putting pure water on the skin (hello long baths!) is drying.
One more thing: the water used in cosmetics is purified and deionized (it means that almost all of the mineral ions inside it is removed). Like this, the products can stay more stable over time.
A nice, multi-functional helper ingredient that's especially useful in sunscreens. It can solubilize some commonly used UV-filters like Oxybenzone or Avobenzone and it can also help to increase the SPF rating of sunscreens. It's also cosmetically elegant, has excellent spreadability and a pleasant, moisturizing skin feel. Oh, and according to Wikipedia, it even helps to stabilize famously unstable UVA-filter, Avobenzone.
A light emollient ester (C8-10 fatty acids connected to C12-18 fatty alcohols) that absorbs quickly and leaves a dry but silky finish on the skin. In terms of skin feel, it is similar to Dicaprylyl Carbonate, another commonly used light emollient.
A light, velvety, unique skin feel liquid that is a good solvent and also makes the skin feel nice and smooth (aka emollient). It's often used in makeup products mixed with silicones to give shine and slip to the product. It's also great for cleansing dirt and oil from the skin as well as for taking off make-up.
Butylene glycol, or let’s just call it BG, is a multi-tasking colorless, syrupy liquid. It’s a great pick for creating a nice feeling product.
BG’s main job is usually to be a solvent for the other ingredients. Other tasks include helping the product to absorb faster and deeper into the skin (penetration enhancer), making the product spread nicely over the skin (slip agent), and attracting water (humectant) into the skin.
It’s an ingredient whose safety hasn’t been questioned so far by anyone (at least not that we know about). BG is approved by Ecocert and is also used enthusiastically in natural products. BTW, it’s also a food additive.
A clear, colorless and odorless, highly volatile (meaning it does not absorb into the skin but evaporates from it) liquid that's used as an emollient. It gives a nice non-oily light skin feel and it can improve the slip of the formula without leaving a tacky residue behind.
It's also popular in make-up products as its volatility makes mascaras and foundations last longer. If that would not be enough, it's also an excellent solvent, and it's a regular not only on the ingredients lists of make-ups but also on makeup removers.
It’s pretty much the current IT-preservative. It’s safe and gentle, but even more importantly, it’s not a feared-by-everyone-mostly-without-scientific-reason paraben.
It’s not something new: it was introduced around 1950 and today it can be used up to 1% worldwide. It can be found in nature - in green tea - but the version used in cosmetics is synthetic.
Other than having a good safety profile and being quite gentle to the skin it has some other advantages too. It can be used in many types of formulations as it has great thermal stability (can be heated up to 85°C) and works on a wide range of pH levels (ph 3-10).
It’s often used together with ethylhexylglycerin as it nicely improves the preservative activity of phenoxyethanol.
A so-called dispersant or dispersing agent that's used in inorganic (titanium dioxide/zinc oxide based) sunscreens or in make-up products to help to distribute the pigments nicely and evenly on the skin. It's also claimed to increase the UV absorption of the sunscreen formula as well as to reduce the annoying white cast left behind by inorganic sunscreens.
A clear, light yellow liquid that is used to coat pigments (such as inorganic sunscreen agents or colorants) in cosmetic products. The coating helps to stabilize pigments in the formulas and also helps them to spread easily and evenly on the skin.
It's a helper ingredient that helps to thicken up formulas and form a nice gel texture. It leaves a rich, elegant feel with a velvety finish on the skin and works over a wide pH range.
A natural polymer (big molecules from repeated subunits) that is harvested from the Acacia tree in the sub-Saharan region in Africa. It's a great thickening and binding agent. Often coupled with xanthan gum, as it helps to reduce its unpleasant stickiness.
A type of silicone elastomer (rubber-like material with both viscosity and elasticity) whose major function is forming a nice film on the skin.
It is also cosmetically very elegant with a non-tacky, non-oily and smooth skin feel. It also works as a stable delivery system of active materials, has sebum absorption and control properties and upon application, it transforms into a matte appearance with a powdery after feel.
It's one of the most commonly used thickeners and emulsion stabilizers. If the product is too runny, a little xanthan gum will make it more gel-like. Used alone, it can make the formula sticky and it is a good team player so it is usually combined with other thickeners and so-called rheology modifiers (helper ingredients that adjust the flow and thus the feel of the formula). The typical use level of Xantha Gum is below 1%, it is usually in the 0.1-0.5% range.
Btw, Xanthan gum is all natural, a chain of sugar molecules (polysaccharide) produced from individual sugar molecules (glucose and sucrose) via fermentation. It’s approved by Ecocert and also used in the food industry (E415).
Tetrahexyldecyl Ascorbate is a stable, oil-soluble form of skincare big shot Vitamin C. If you do not know, why Vitamin C is such a big deal in skincare, click here and read all about it. We are massive vitamin C fans and have written about it in excruciating detail.
So now, you know that Vitamin C is great and all, but it's really unstable and gives cosmetics companies many headaches. To solve this problem they came up with vitamin C derivatives, and one of them is Tetrahexyldecyl Ascorbate (let's call it THDA in short).
It's a really promising candidate (see below), but while reading all the goodness about it in a minute, do not forget that derivatives not only have to be absorbed into the skin but also have to be converted to pure vitamin C (ascorbic acid or AA) and the efficacy of the conversion is often unknown. In addition, vitamin C's three magic properties (antioxidant, collagen booster, skin brightener) are all properly proven in-vivo (on real people), but for the derivatives, it's mostly in-vitro studies or in the case of THDA, it's in-vitro and done by an ingredient supplier.
With this context in mind let's see what THDA might be able to do. First, it is stable (if pH < 5), easy to formulate, and a joy to work with for a cosmetic chemist.
Second, because it's oil-soluble, its skin penetration abilities seem to be great. So great in fact, that it surpasses the penetration of pure vitamin C threefold at the same concentration and it penetrates successfully into the deeper layers of the skin (that is usually important to do some anti-aging work). There is also in-vitro data showing that it converts to AA in the skin.
Third, THDA seems to have all three magic abilities of pure vitamin C: it gives antioxidant protection from both UVB and UVA rays, it increases collagen synthesis (even more than AA) and it has a skin brightening effect by reducing melanogenesis by more than 80% in human melanoma cell cultures.
So this all sounds really great, but these are only in-vitro results at this point. We could find Tetrahexyldecyl Ascorbate mentioned only in one published in-vivo study that examined the anti-aging properties of a silicone formula containing 10% AA and 7% THDA. The authors theorized that the 10% AA is released slowly from the silicon delivery system and probably stays in the upper layer of the skin to give antioxidant benefits, while THDA penetrates more rapidly and deeply and gives some wrinkle-reducing benefits. The study was a small (10 patients), double-blind experiment, and the formula did show some measurable anti-aging results. However, it is hard to know how much pure vitamin C or THDA can be thanked.
Bottom line: a really promising, but not well-proven vitamin C derivative that can be worth a try especially if you like experimenting (but if you like the tried and true, pure vitamin C will be your best bet).
If you have spotted ethylhexylglycerin on the ingredient list, most probably you will see there also the current IT-preservative, phenoxyethanol. They are good friends because ethylhexylglycerin can boost the effectiveness of phenoxyethanol (and other preservatives) and as an added bonus it feels nice on the skin too.
Also, it's an effective deodorant and a medium spreading emollient.
This long-named, polymer molecule (big molecule from repeated subunits) is a helper ingredient that's good at emulsifying and stabilizing oils into water-based formulas. It also acts as a thickening and gelling agent that creates nice, non-sticky and supple textures. It works over a very wide pH range (3-12) and can be used to thicken up low-ph formulas, such as exfoliants. Its recommended used range is 0.3-3%.
It seems to us that squalane is in fashion and there is a reason for it. Chemically speaking, it is a saturated (no double bonds) hydrocarbon (a molecule consisting only of carbon and hydrogen), meaning that it's a nice and stable oily liquid with a long shelf life.
It occurs naturally in certain fish and plant oils (e.g. olive), and in the sebum (the oily stuff our skin produces) of the human skin. As f.c. puts it in his awesome blog post, squalane's main things are "emolliency, surface occlusion, and TEWL prevention all with extreme cosmetic elegance". In other words, it's a superb moisturizer that makes your skin nice and smooth, without being heavy or greasy.
Another advantage of squalane is that it is pretty much compatible with all skin types and skin conditions. It is excellent for acne-prone skin and safe to use even if you have fungi-related skin issues, like seborrhea or fungal acne.
The unsaturated (with double bonds) and hence less stable version of Squalane is Squalene, you can read about it here >>
Super common little helper ingredient that helps products to remain nice and stable for a longer time. It does so by neutralizing the metal ions in the formula (that usually get into there from water) that would otherwise cause some not so nice changes.
It is typically used in tiny amounts, around 0.1% or less.
A common little helper ingredient that helps water and oil to mix together, aka emulsifier.
It’s the - sodium form - cousin of the famous NMF, hyaluronic acid (HA). If HA does not tell you anything we have a super detailed, geeky explanation about it here. The TL; DR version of HA is that it's a huge polymer (big molecule from repeated subunits) found in the skin that acts as a sponge helping the skin to hold onto water, being plump and elastic. HA is famous for its crazy water holding capacity as it can bind up to 1000 times its own weight in water.
As far as skincare goes, sodium hyaluronate and hyaluronic acid are pretty much the same and the two names are used interchangeably. As cosmetic chemist kindofstephen writes on reddit "sodium hyaluronate disassociates into hyaluronic acid molecule and a sodium atom in solution".
In spite of this, if you search for "hyaluronic acid vs sodium hyaluronate" you will find on multiple places that sodium hyaluronate is smaller and can penetrate the skin better. Chemically, this is definitely not true, as the two forms are almost the same, both are polymers and the subunits can be repeated in both forms as much as you like. (We also checked Prospector for sodium hyaluronate versions actually used in cosmetic products and found that the most common molecular weight was 1.5-1.8 million Da that absolutely counts as high molecular weight).
What seems to be a true difference, though, is that the salt form is more stable, easier to formulate and cheaper so it pops up more often on the ingredient lists.
If you wanna become a real HA-and-the-skin expert you can read way more about the topic at hyaluronic acid (including penetration-questions, differences between high and low molecular weight versions and a bunch of references to scientific literature).
The unfancy name for it is lye. It’s a solid white stuff that’s very alkaline and used in small amounts to adjust the pH of the product and make it just right.
For example, in case of AHA or BHA exfoliants, the right pH is super-duper important, and pH adjusters like sodium hydroxide are needed.
BTW, lye is not something new. It was already used by ancient Egyptians to help oil and fat magically turn into something else. Can you guess what? Yes, it’s soap. It still often shows up in the ingredient list of soaps and other cleansers.
Sodium hydroxide in itself is a potent skin irritant, but once it's reacted (as it is usually in skin care products, like exfoliants) it is totally harmless.
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| what‑it‑does | sunscreen |
| what‑it‑does | sunscreen |
| irritancy, com. | 0, 1 |
| what‑it‑does | solvent |
| what‑it‑does | solvent |
| what‑it‑does | emollient |
| what‑it‑does | emollient | solvent |
| what‑it‑does | moisturizer/humectant | solvent |
| irritancy, com. | 0, 1 |
| what‑it‑does | emollient | solvent |
| what‑it‑does | preservative |
| what‑it‑does | emulsifying |
| what‑it‑does | viscosity controlling |
| what‑it‑does | viscosity controlling |
| what‑it‑does | antioxidant | skin brightening |
| what‑it‑does | preservative |
| what‑it‑does | viscosity controlling |
| what‑it‑does | skin-identical ingredient | emollient |
| irritancy, com. | 0, 1 |
| what‑it‑does | chelating |
| what‑it‑does | emulsifying | surfactant/cleansing |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | buffering |