Fluid 100 SPF 100
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Rilastil Fluid 100 SPF 100Ingredients explained
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 super commonly used 5 unit long, cyclic structured silicone that is water-thin and does not stay on the skin but evaporates from it (called volatile silicone). Similar to other silicones, it gives skin and hair a silky, smooth feel.
It's often combined with the non-volatile (i.e. stays on the skin) dimethicone as the two together form a water-resistant, breathable protective barrier on the skin without a negative tacky feel.
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.
- It's a super common and super debated skincare ingredient
- It has several benefits: great solvent, penetration enhancer, creates cosmetically elegant, light formulas, great astringent and antimicrobial
- It can be very drying if it's in the first few ingredients on an ingredient list
- Some experts even think that regular exposure to alcohol damages skin barrier and causes inflammation though it's a debated opinion (read more in geeky details tab)
A clear, colorless, odorless oily liquid that makes the formula easily spreadable and also makes the skin nice and smooth (emollient). It's especially helpful in sunscreens as it can help to solubilize UV filters.
A very low viscosity and high spreadability emollient fluid that gives a nice light skin feel. It can also be used to solubilize crystalline actives such as chemical UV filters.
A light-feeling, volatile (meaning it does not absorb into the skin but evaporates from it) silicone that gives skin a unique, silky and non-greasy feel. It has excellent spreading properties and leaves no oily residue or build-up.
Titanium Dioxide is one of the two members of the elite sunscreen group called physical sunscreens (or inorganic sunscreens if you’re a science geek and want to be precise).
Traditionally, UV-filters are categorized as either chemical or physical. The big difference is supposed to be that chemical agents absorb UV-light while physical agents reflect it like a bunch of mini umbrellas on top of the skin. While this categorization is easy and logical it turns out it's not true. A recent, 2016 study shows that inorganic sunscreens work mostly by absorption, just like chemical filters, and only a little bit by reflection (they do reflect the light in the visible spectrum, but mostly absorb in the UV spectrum).
Anyway, it doesn't matter if it reflects or absorbs, Titanium Dioxide is a pretty awesome sunscreen agent for two main reasons: it gives a nice broad spectrum coverage and it's highly stable. Its protection is very good between 290 - 350 nm (UVB and UVA II range), and less good at 350-400 nm (UVA I) range. Regular sized Titanium Dioxide also has a great safety profile, it's non-irritating and is pretty much free from any health concerns (like estrogenic effect worries with some chemical filters).
The disadvantage of Titanium Dioxide is that it's not cosmetically elegant, meaning it's a white, "unspreadable" mess. Sunscreens containing Titanium Dioxide are often hard to spread on the skin and they leave a disturbing whitish tint. The cosmetic industry is, of course, really trying to solve this problem and the best solution so far is using nanoparticles. The itsy-bitsy Nano-sized particles improve both spreadability and reduce the whitish tint a lot, but unfortunately, it also introduces new health concerns.
The main concern with nanoparticles is that they are so tiny that they are absorbed into the skin more than we want them (ideally sunscreen should remain on the surface of the skin). Once absorbed they might form unwanted complexes with proteins and they might promote the formation of evil free radicals. But do not panic, these are concerns under investigation. A 2009 review article about the safety of nanoparticles summarizes this, "to date, in-vivo and in-vitro studies have not demonstrated percutaneous penetration of nanosized particles in titanium dioxide and zinc oxide sunscreens". The English translation is, so far it looks like sunscreens with nanoparticles do stay on the surface of the skin where they should be.
All in all, Titanium Dioxide is a famous sunscreen agent and for good reason, it gives broad spectrum UV protection (best at UVB and UVA II), it's highly stable, and it has a good safety profile. It's definitely one of the best UV-filter agents we have today, especially in the US where new-generation Tinosorb filters are not (yet) approved.
The famous Avobenzone. It is a special snowflake as it is the only globally available chemical sunscreen agent that provides proper UVA protection (in the US, new generation sunscreen agents are not approved because of impossible FDA regulations). It is the global gold standard of UVA protection and is the most used UVA sunscreen in the world.
It gives very good protection across the whole UVA range (310-400 nm that is both UVA1 and UVA2) with a peak protection at 360 nm. The problem with it, though, is that it is not photostable and degrades in the sunlight. Wikipedia says that avobenzone loses 36% of its UV-absorption capacity after just one hour of sunlight (yep, this is one of the reasons why sunscreens have to be reapplied after a few hours).
The cosmetic's industry is trying to solve the problem by combining avobenzone with other UV filters that enhance its stability (like octocrylene, Tinosorb S or Ensulizole) or by encapsulating it and while both solutions help, neither is perfect. Interestingly, the combination of avobenzone with mineral sunscreens (that is titanium dioxide and zinc oxide) is not a good idea. In the US, it is flat out prohibited as avobenzone becomes unstable when combined with mineral sunscreens.
As for safety, avobenzone has a pretty good safety profile. It counts as non-irritating, and unlike some other chemical sunscreens, it shows no estrogenic effect. The maximum concentration of avobenzone permitted is 5% in the EU and 3% in the US.
Its INCI name is a bit of a mouthful, but Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine is worth recognizing it as it is one of the best sunscreen agents known today. Unfortunately, it's not FDA-approved so you will not find it in sunscreens coming from the US (not because it's not good, but because US regulations make it impossible for newer sunscreen agents to get approved), but it is widely available in other parts of the world like Europe, Australia or Asia.
It is a broad-spectrum (covers the whole UVB and UVA range, 280-400 nm) chemical sunscreen agent with peak protections at about 310 and 345 nm and unlike older UV filters, it's very photostable. It hardly deteriorates in the presence of UV light and it's also useful in stabilizing other less stable sunscreen agents, like the famous UVA protector, avobenzone.
It's a new generation sunscreen agent that was specifically designed for high SPF and good UVA protection and based on a 2007 study that compared 18 sunscreen agents available in the EU it really had the best SPF protection (they used the highest concentration allowed by EU regulations from each 18 sunscreens and Trinosorb S gave an SPF 20 all by itself).
It is an oil-soluble, slightly yellowish powder that is not absorbed into the skin too much. This is good news for a sunscreen agent as it needs to be on the surface of the skin to do its job properly. Regarding Bis-Ethylhexyloxyphenol Methoxyphenyl Triazine side effects, we have good news here as well: it has a great safety profile and unlike a couple of other chemical sunscreens, Trinosorb S (and M) does not show estrogenic activity.
Overall, we think Trinosorb S is one of the best sunscreen options available today.
Are you into sunscreen agents? We have shiny explanations (along with product lists) about others as well:
- Methylene Bis-Benzotriazolyl Tetramethylbutylphenol, aka Tinosorb M, the good buddy of our current molecule Tinosorb S
- Tris-Biphenyl Triazine, aka Tinosorb A2B, the newest addition to the Tinosorb family that protects strongly in an in-between wavelength that most other filters miss
- Ethylhexyl Triazone, aka Uvinul T 150, another new generation sunscreen agent with super-high UVB protection
- Diethylamino Hydroxybenzoyl Hexyl Benzoate, aka Uvinul A Plus, a new generation sunscreen for UVA protection
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.
PEG-30 Dipolyhydroxystearate is a popular water-in-oil (w/o) emulsifier, meaning that it helps the oily and watery parts of the formula to mix in a way where water droplets are dispersed in the continuous oil phase and not the other way round.
Compared to the more commonly used oil-in-water (o/w) emulsions, w/o emulsions tend to be heavier and less cosmetically elegant, but PEG-30 Dipolyhydroxystearate is claimed to help with this and enables a light and elegant skin feel. It also has a molecular structure that creates large anchors both in the water and in the oil phase making the resulting emulsion not only cosmetically elegant but also very stable.
A silicone emulsifier that helps water and silicone oils to mix nicely together. It can also be used together with plant oil + silicone oil mixtures.
A so-called polymer microsphere, i.e. little spherical shaped particles from repeated subunits. Similar to other microsphere powders, it can scatter the light to give products a soft focus or blurring effect. It also works as a texture enhancer giving formulas an exceptional smoothness and a velvet touch.
- A multi-functional skincare superstar with several proven benefits for the skin
- Great anti-aging, wrinkle smoothing ingredient used at 4-5% concentration
- Fades brown spots alone or in combination with amino sugar, acetyl glucosamine
- Increases ceramide synthesis that results in a stronger, healthier skin barrier and better skin hydration
- Can help to improve several skin conditions including acne, rosacea, and atopic dermatitis
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).
It's one of the active parts of Chamomile that contains about 30% of bisabolol. It's a clear oily fluid that is used in skincare as a nice anti-inflammatory and soothing ingredient.
A biologically active component that can be found in rice bran oil. It has natural antioxidant properties and can help to stabilize other unstable plant oils. Interestingly, it also seems to possess some natural sunscreen abilities.
It’s the most commonly used version of pure vitamin E in cosmetics. You can read all about the pure form here. This one is the so-called esterified version.
According to famous dermatologist, Leslie Baumann while tocopheryl acetate is more stable and has a longer shelf life, it’s also more poorly absorbed by the skin and may not have the same awesome photoprotective effects as pure Vit E.
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
We don't have description for this ingredient yet.
Sodium chloride is the fancy name of salt. Normal, everyday table salt.
If (similar to us) you are in the weird habit of reading the label on your shower gel while taking a shower, you might have noticed that sodium chloride is almost always on the ingredient list. The reason for this is that salt acts as a fantastic thickener in cleansing formulas created with ionic cleansing agents (aka surfactants) such as Sodium Laureth Sulfate. A couple of percents (typically 1-3%) turns a runny surfactant solution into a nice gel texture.
If you are into chemistry (if not, we understand, just skip this paragraph), the reason is that electrolytes (you know, the Na+ and Cl- ions) screen the electrostatic repulsion between the head groups of ionic surfactants and thus support the formation of long shaped micelles (instead of spherical ones) that entangle like spaghetti, and viola, a gel is formed. However, too much of it causes the phenomenon called "salting out", and the surfactant solution goes runny again.
Other than that, salt also works as an emulsion stabilizer in water-in-oil emulsions, that is when water droplets are dispersed in the outer oil (or silicone) phase. And last but not least, when salt is right at the first spot of the ingredient list (and is not dissolved), the product is usually a body scrub where salt is the physical exfoliating agent.
A white powdery thing that's the major component of glass and sand. In cosmetics, it’s often in products that are supposed to keep your skin matte as it has great oil-absorbing abilities. It’s also used as a helper ingredient to thicken up products or suspend insoluble particles.
An organic derivative of hectorite clay, Disteardimonium Hectorite is used as a viscosity controller - it thickens up formulations to make them less runny.
It’s most popular use in cosmetics is in sunscreens, under the trademarked name Bentone 38 from Elementis. According to the manufacturer info, it is a real multi-tasker, including the ability to prevent pigments settling during storage, stabilizing a formula for longer, creating a light and smooth skin feel and enhancing the water-resistance of sunscreen formulas.
- A natural moisturizer that’s also in our skin
- A super common, safe, effective and cheap molecule used for more than 50 years
- Not only a simple moisturizer but knows much more: keeps the skin lipids between our skin cells in a healthy (liquid crystal) state, protects against irritation, helps to restore barrier
- Effective from as low as 3% with even more benefits for dry skin at higher concentrations up to 20-40%
- High-glycerin moisturizers are awesome for treating severely dry skin
Probably the most common silicone of all. It is a polymer (created from repeating subunits) molecule and has different molecular weight and thus different viscosity versions from water-light to thick liquid.
As for skincare, it makes the skin silky smooth, creates a subtle gloss and forms a protective barrier (aka occlusive). Also, works well to fill in fine lines and wrinkles and give skin a plump look (of course that is only temporary, but still, it's nice). There are also scar treatment gels out there using dimethicone as their base ingredient. It helps to soften scars and increase their elasticity.
As for hair care, it is a non-volatile silicone meaning that it stays on the hair rather than evaporates from it and smoothes the hair like no other thing. Depending on your hair type, it can be a bit difficult to wash out and might cause some build-up (btw, this is not true to all silicones, only the non-volatile types).
A super common, waxy, white, solid stuff that helps water and oil to mix together, gives body to creams and leaves the skin feeling soft and smooth.
Chemically speaking, it is the attachment of a glycerin molecule to the fatty acid called stearic acid. It can be produced from most vegetable oils (in oils three fatty acid molecules are attached to glycerin instead of just one like here) in a pretty simple, "green" process that is similar to soap making. It's readily biodegradable.
It also occurs naturally in our body and is used as a food additive. As cosmetic chemist Colins writes it, "its safety really is beyond any doubt".
A thick, high molecular weight silicone that is usually diluted in another, lighter silicone fluid (like dimethicone or cyclopentasiloxane). The dimethiconol containing silicone blends leave a silky smooth, non-greasy film on the skin.
The big brother of glycerin. It's also a natural moisturizing factor that reduces water evaporation from the upper layer of the skin and helps to keep water in the skin so that it stays nicely hydrated.
Compared to glycerin, it has a larger molecular structure (kind of a double glycerin). Thanks to this, it penetrates slower into the skin but gives longer lasting moisture and less sticky, better skin-feel.
A smallish polymer molecule (created from repeated units of Polyethylene glycol, aka PEG) that's used as a solubilizer and viscosity control agent.
It is a clear, colorless liquid that is water-soluble and water-binding (aka humectant) and can help to solubilize sparingly-water soluble things (e.g. vanilla, perfumes) into water-based formulas. Thanks to its water-binding ability, it also prevents the drying out of formulas, especially when combined with the fellow hygroscopic agent, sorbitol.
- Primary fat-soluble antioxidant in our skin
- Significant photoprotection against UVB rays
- Vit C + Vit E work in synergy and provide great photoprotection
- Has emollient properties
- Easy to formulate, stable and relatively inexpensive
A form of skincare superstar, vitamin C. Even though we are massive vitamin C fans, Ascorbyl Palmitate (AP) is our least favorite. (Btw, if you do not know what the big deal with vitamin C is then you are missing out. You must go and read our geeky details about it.)
So, AP is one of the attempts by the cosmetics industry to solve the stability issues with vitamin C while preserving its benefits, but it seems to fall short on several things.
What's the problem?
Firstly, it's stability is only similar to that of pure ascorbic acid (AA), which means it is not really stable. A great study in the Journal of Cosmetic Dermatology compared a bunch of vitamin C derivatives and this derivative was the only one where the study said in terms of stability that it's "similar to AA". Not really that good.
Second, a study that examined the skin absorption of vitamin C found that ascorbyl palmitate did not increase the skin levels of AA. This does not mean that ascorbyl palmitate cannot penetrate the skin (because it can, it's oil soluble and the skin likes to absorb oil soluble things) but this means that it's questionable if ascorbyl palmitate can be converted into pure Vit C in the skin. Even if it can be converted, the palmitate part of the molecule is more than the half of it, so the efficacy will not be good and we have never seen a serum that contains a decent (and proudly disclosed) amount of AP. We are highly skeptical what effect a tiny amount of AP has in a formula.
Third, another study that wanted to examine the antioxidant properties of AP was surprised to find that even though AP does have nice antioxidant properties; following UVB radiation (the same one that comes from the sun) it also promotes lipid peroxidation and cytotoxicity. It was only an in-vitro study meaning that it was done on cell cultures and not on real people, but still, this also does not support the use of AP too much.
The only good thing we can write about Ascorbyl Palmitate is that there is an in-vitro (made in the lab, not on real people) study showing that it might be able to boost collagen production.
Regarding the skin-brightening properties of pure vitamin C, this is another magic property AP does not have, or at least there is no data, not even in-vitro, about it.
Overall, Ascorbyl Palmitate is our least favorite vitamin C derivative. It is there in lots of products in tiny amounts (honestly, we do not really understand why), however, we do not know about any vitamin C serum featuring AP in high amounts. That is probably no coincidence. If you are into vitamin C, you can take a look at more promising derivatives here.
- Works best between a concentration of 5-20%
- Boosts the skin’s own collagen production
- Fades pigmentation and brown spots
- If used under sunscreen it boosts its UV protection
- Extremely unstable and oxidizes very easily in presence of light or air
- Stable in solutions with water only if pH is less than 3.5 or in waterless formulations
- Vit E + C work in synergy and provide superb photoprotection
- Ferulic acid doubles the photoprotection effect of Vit C+E and helps to stabilize Vit C
- Potent Vit. C serums might cause a slight tingling on sensitive skin
Citric acid comes from citrus fruits and is an AHA. If these magic three letters don’t tell you anything, click here and read our detailed description on glycolic acid, the most famous AHA.
So citric acid is an exfoliant, that can - just like other AHAs - gently lift off the dead skin cells of your skin and make it more smooth and fresh.
There is also some research showing that citric acid with regular use (think three months and 20% concentration) can help sun-damaged skin, increase skin thickness and some nice hydrating things called glycosaminoglycans in the skin.
But according to a comparative study done in 1995, citric acid has less skin improving magic properties than glycolic or lactic acid. Probably that’s why citric acid is usually not used as an exfoliant but more as a helper ingredient in small amounts to adjust the pH of a formulation.
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.
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.
A helper ingredient that helps to make the products stay nice longer, aka preservative. It works mainly against fungi.
It’s pH dependent and works best at acidic pH levels (3-5). It’s not strong enough to be used in itself so it’s always combined with something else, often with potassium sorbate.
It's one of those things that help your cosmetics not to go wrong too soon, aka a preservative. It’s not a strong one and doesn’t really work against bacteria, but more against mold and yeast. To do that it has to break down to its active form, sorbic acid. For that to happen, there has to be water in the product and the right pH value (pH 3-4).
But even if everything is right, it’s not enough on its own. If you see potassium sorbate you should see some other preservative next to it too.
BTW, it’s also a food preservative and even has an E number, E202.
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.
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| what‑it‑does | solvent |
| what‑it‑does | emollient | solvent |
| what‑it‑does | sunscreen |
| what‑it‑does | antimicrobial/antibacterial | solvent | viscosity controlling |
| what‑it‑does | emollient | solvent |
| what‑it‑does | emollient |
| what‑it‑does | emollient | solvent |
| what‑it‑does | sunscreen | colorant |
| what‑it‑does | sunscreen |
| what‑it‑does | sunscreen |
| what‑it‑does | moisturizer/humectant | solvent |
| irritancy, com. | 0, 1 |
| what‑it‑does | emulsifying |
| what‑it‑does | emulsifying |
| what‑it‑does | cell-communicating ingredient | skin brightening | anti-acne | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | soothing |
| what‑it‑does | antioxidant |
| what‑it‑does | antioxidant |
| irritancy, com. | 0, 0 |
| what‑it‑does | antimicrobial/antibacterial | antioxidant |
| what‑it‑does | viscosity controlling |
| what‑it‑does | viscosity controlling |
| what‑it‑does | viscosity controlling |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| irritancy, com. | 0, 0 |
| what‑it‑does | emollient |
| irritancy, com. | 0, 1 |
| what‑it‑does | emollient | emulsifying |
| irritancy, com. | 0, 1 |
| what‑it‑does | emollient | moisturizer/humectant |
| what‑it‑does | skin-identical ingredient | moisturizer/humectant |
| what‑it‑does | moisturizer/humectant | solvent |
| what‑it‑does | antioxidant |
| irritancy, com. | 0-3, 0-3 |
| what‑it‑does | antioxidant |
| irritancy, com. | 0, 2 |
| what‑it‑does | antioxidant | skin brightening | buffering |
| what‑it‑does | buffering |
| what‑it‑does | preservative |
| what‑it‑does | preservative |
| what‑it‑does | preservative |
| what‑it‑does | preservative |
| what‑it‑does | chelating |