24h Cosme Mineral UV Base 40 SPF 40 01 Tone Up

24h Cosme Mineral UV Base 40 SPF 40

Color: 01 Tone Up

This mineral sunscreen covers the full UV range and blocks ~98% of UVB at SPF 40.

Worth noting

Contains drying alcohol, which absorbs quickly but can be dehydrating.

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What's inside

Key Ingredients

Benefits

Concerns

Ingredients Explained

Emollient, Skin Conditioning

Isostearyl Isostearate is a plant-based and vegan emollient ester made by reacting Isostearyl Alcohol and Isostearic Acid.

It helps improve how the product spreads on skin, acts as a binding agent for makeup powders without modifying pigment color, and softens skin while helping it hold onto water.

This ingredient is very interesting as a hydrator; most moisturizers are either occlusives, humectants, or emollients. Isostearyl isostearate works through another route named "internal occlusion" by the head researcher.

Isostearyl isostearate nudges the skin's own lipids into a denser, more tightly packed arrangement. Packing the deeper layers of the stratum corneum together more efficiently means less water is able to escape.

This is a barrier-improving mechanism that hadn't been described before and plastic occlusion stress tests confirmed it improved the skin's water-permeability barrier function

Just one thing worth noting from the same review: this ingredient increased the penetration rate of a test drug through excised human skin. Though this ingredient is not classified as a penetration enhancer, it does interact with the barrier rather than sitting totally inert on top.

Fungal acne:
The Malassezia yeast feeds on fatty acids and esters in the C11-24 range. Since both halves of this molecules are C18, it may not be fungal acne safe.

Learn more about Isostearyl Isostearate
Cosmetic Colorant, Skin Protecting, UV Absorber

Zinc Oxide (ZO) is a mineral broad-spectrum UV filter and the broadest-spectrum filter recognized by the FDA. It covers everything from UVB through to long-wave UVA.

On top of sun protection, it has skin protectant and skin-soothing properties too.

Here's a myth worth busting: mineral filters are usually described as working by "reflecting" or "bouncing" UV off your skin.

That's mostly not true: when researchers actually measured it, ZO and Titanium Dioxide reflect only about 4-5% of UV (less than SPF 2 worth of protection).

The vast majority of the work (~95%) is done by absorption, similar to chemical UV filters. ZO is a semiconductor that absorbs UV photos through its energy band gap.

So the old "physical blocker vs. chemical absorber" framing is really an oversimplification.

Zinc Oxide is one of the most effective broad-spectrum UV filters out there. It protects across UVB, UVA2, and UVA1 with a flat, even absorption curve across the whole UVA-UVB range.

That uniform UVA coverage is its standout feature; titanium dioxide skews more toward UVB as its particle size drops so ZO gives more consistent and extended UVA protection.

It's also very photostable. As an inorganic oxide, ZO doesn't break down in sunlight the way some organic filters can, so it holds up over a day of wear.

This ingredient is gentle and soothing, making it go-to for sunscreens aimed at sensitive skin, rosacea, or ecezma-prone skin, babies, and children.

It's also unlikely to cause the "eye sting" that some sunscreen ingredients are known for, and regulatory agencies broadly consider it non-toxic and safe for topical use.

Beyond sun protection, ZO is also a recognized OTC skin protectant. It forms a breathable barrier that shields skin from moisture and irritation while supporting healing. This is why you'll see it as a classic active in diaper rash creams.

The only downside to ZO is that it can leave a visible white cast, especially on deeper skin tones. This is the main reason mineral sunscreens have historically felt less cosmetically elegant than chemical or hybrid formulas.

Zinc Oxide comes in both non-nano and nano forms. The dividing line is 100nm and anything under is classified as a nanomaterial by the EU.

The nano version scatters less visible light which cuts down white case and gives a lighter, more wearable texture.

Another thing worth understanding about formulation:

Uncoated ZO has some inherent photocatalytic activity. This just means it can generate reactive oxygen species under UV. It's exactly why cosmetic-grade ZO is almost always surface-coated; this coating suppresses that reactivity and improves how the powder disperses and feels.

A well-formulated coated ZO largely sidesteps this issue.

Zinc Oxide is commonly used anywhere from 10% up to the regulatory maximum in sunscreens (25%).

Mineral-only broad-spectrum products often land in the 15-25% range to hit higher SPF and UVA values. Keep in mind SPF performance depends heavily on particle size, dispersion, and the rest of the formula, and not just the percentage.

As an OTC skin protectant like diaper creams, ZO typically runs higher at roughly 10-40%.

This ingredient is generally easy to work with and doesn't photodegrade.

The only thing to know is that uncoated ZO can be a bit reactive in a formula.

Under UV, it can break down sensitive ingredients like other actives or UV filters. This is another reason coated versions are standard. ZO can also react with very acidic ingredients or throw off stability of some creams. A good formula will get around this with the right coatings and dispersion.

The EU's Scientific Committee on Consumer Safety has concluded that ZO nanoparticles "can be considered to not pose any risk of adverse effects in humans after application on healthy, intact or sunburnt skin".

You might hear that ZO is "toxic"; this is because an in-vitro (test tube) study suggested micronized ZO had potential phototoxicity. In vivo (human) investigations have disputed this and the results have come back reassuring.

So does ZO penetrate skin? The short answer is no, not in any way that matters.

The most relevant evidence comes from real-world human studies: in one, volunteers applied ZO nanoparticle sunscreen hourly for six hours and daily for five days. The advanced imaging showed the particles stayed on the surface and never reached the living epidermis, and no cellular toxicity was found.

Other in-vivo and ex-vivo work agree; ZO nanoparticles don't cross the stratum corneum, even on flexed, massaged, or barrier-impaired skin.

A small amount of solubilized zinc ions can dissolve off the particles and enter the upper skin. But the quantities are tiny compared to the zinc already naturally present in your body, and studies haven't found this to cause local toxicity.

The sunscreen bans you've heard of (like Hawaii's) are aimed at two chemical filters, Oxybenzone and Octinoxate. ZO itself it not banned and is often recommended instead.

So far, there's no solid evidence that any form of ZO harms reefs. It is an ongoing and active area of study, and worth keeping an eye on.

If you're traveling somewhere with these rules, a non-nano mineral sunscreen is the safe bet.

Learn more about Zinc Oxide
Skin Conditioning, Solvent

Water. It's the most common cosmetic ingredient of all. You'll usually see it at the top of ingredient lists, meaning that it makes up the largest part of the product.

So why is it so popular? Water most often acts as a solvent - this means that it helps dissolve other ingredients into the formulation.

You'll also recognize water as that liquid we all need to stay alive. If you see this, drink a glass of water. Remember to stay hydrated!

Learn more about Water
Emollient, Perfuming

Dodecane is a lightweight alkane hydrocarbon that functions as an emollient, texture enhancer, and fragrance.

According to a manufacturer, it evaporates fast on skin and leaves behind a non-greasy and velvety finish. This also helps other ingredients like UV filters and pigments distribute evenly.

In 2020, the Research Institute for Fragrance Materials (RIFM) reviewed dodecane and found it to clear all tests. The amount typically used in cosmetics is also well below the threshold where skin allergies would be a concern.

This ingredient can be sourced from either petroleum fractionation or plant-based feedstocks.

Learn more about Dodecane

Polyglyceryl-2 Triisostearate is a plant-derived emulsifier and pigment-dispersing agent with a non-sticky skin feel.

It helps products glide on smoothly and prevents oil and water from separating in a formula, making it suitable for sunscreen and makeup formulations.

The EU inventory of cosmetics has no use restrictions on this ingredient and it is considered well-tolerated.

This ingredient may not be fungal acne safe because it is derived from isostearic acid.

Learn more about Polyglyceryl-2 Triisostearate
Cosmetic Colorant, UV Absorber, UV Filter

Titanium Dioxide (TD) is a mineral UV filter widely used in sunscreens and cosmetics.

It's one of only two UV filters officially classified as "mineral" by regulatory agencies (the other being Zinc Oxide).

A really common myth is that mineral filters work by reflecting UV light off your skin like tiny mirrors.

They don't only do that; modern research shows TD protects mostly by absorbing UV radiation, the same way chemical filters do.

When researchers measured this, reflection accounted for only about 4-5% of the protection (and less than SPF 2 on its own). The other ~95% comes from absorption: the UV photons hit the particle and their energy gets soaked up by its semiconductor band gap rather than bouncing off.

So "reflects vs. absorbs" was never really the right way to split mineral from chemical filters.

TD gives broad-spectrum protection that's strongest in the UVB and UVA-2 range and weaker in the UVA-1 range. Its UVA protection isn't quite as strong as Zinc Oxide's which is why you'll often see the two paired together.

Together, they make a solid broad-spectrum system.

TD is a great pick for sensitive, acne-prone, or redness-prone skin because it's non-irritating and chemically inert. Regulatory reviews classify it as a non-sensitizer and mild-to-non-irritant.

It's also unlikely to cause the "eye sting" some chemical filters are known for.

The main trade-off is cosmetic; TD can leave a white cast and has a thicker texture. This is why mineral sunscreens are often less cosmetically elegant than chemical or hybrid formulas (and harder to shade-match on deeper skin tones).

Formulators often use micronized or nano-sized TD to cut down on white case and improve spreadability. Smaller particles scatter less visible light so the formula looks less chalky while still filtering UV.

TD is almost always bundled with coatings like Alumina, Silica, Stearic Acid, or Dimethicone. These coatings do two important jobs:

TD can be used at up to 25% in a finished sunscreen; this is the regulatory ceiling in both the US and the EU.

In practice, the amount in any given product varies a lot depending on the target SPF and whether it's paired with other UV filters.

TD is one of the most heavily vetted sunscreen ingredients out there. It is approved as a UV filter in all major markets worldwide, including the US, EU, UK, Japan, Korea, China, Australia, and Canada.

The safety evidence is solid. There was an old worry that nano particles might absorb through skin into the body but multiple studies (including on damaged, sunburned, and UV-irradiated skin) have shown that TD stays on the surface and the layer of dead skin cells on top of everything else.

There's also no evidence of carcinogenicity, mutagenicity, or reproductive toxicity from dermal exposure of this ingredient.

For those who have seen the headline about a 2022 EU ban on TD, that was on TD as a food additive (a complete separate use from topical sunscreen).

There are ongoing questions about how nano-TD might affect marine ecosystems. As of now, there has been no conclusive evidence that any form of TD (or any other sunscreen filter) harms coral reefs or marine life.

The science is still developing and it's a space worth watching rather than packing over.

However, several destinations have reef-safety sunscreen rules that restrict certain chemical filters and steer visitors toward mineral, non-nano options. If you're traveling somewhere with these rules, a non-nano mineral sunscreen is the safe bet.

Learn more about Titanium Dioxide
Solvent

Propanediol is an all-star ingredient. It softens, hydrates, and smooths the skin. 

It’s often used to:

Propanediol is not likely to cause sensitivity and considered safe to use. It is derived from corn or petroleum with a clear color and no scent.

Learn more about Propanediol

Polyglyceryl-2 Diisostearate isn't fungal acne safe.

Cleansing, Emulsifying, Surfactant

Isostearic Acid is a fatty acid and a structural cousin of stearic acid. It is an emulsifier.

The branched structure of this ingredient enhances fluidity and gives it a lighter, less greasy feel compared to other fatty acids. It helps improve texture and consistency because it prevents oil and water phases from separating.

This ingredient is sourced from plant-based oils like soybean or rapeseed.

Clinical studies found no signs of irritation from this ingredient.

Since Isostearic Acid is an 18-carbon fatty acid, it is in the range that Malassezia can feed on. This ingredient may not be fungal acne safe.

You might have seen sources that this ingredient is comedogenic. The original comedogenic testing on rabbit ear actually tested the ester, Isopropyl Isostearate and not Isostearic acid itself. There has been no comedogenic testing done on this ingredient, but it may be worth patch testing if you have acne-prone skin.

Learn more about Isostearic Acid
Emollient, Skin Conditioning

You may know this ingredient as argan oil. It has emollient and skin conditioning properties that help soften skin and reinforce the lipid barrier.

The fatty acid profile of argan oil is roughly 45-55% oleic acid, 28-36% linoleic acid, 10-15% palmitic acid, and 5-7% stearic acid. It also contains vitamin E, sterols, squalene, and polyphenols like ferulic acid.

Two clinical studies in postmenopausal women found that applying argan oil for 60 days significantly improved skin elasticity and moisturization (reduced transepidermal water loss and increased epidermal water content).

Since it is high in oleic and linoleic acid, this ingredient may not be fungal acne safe. Both of these fall in the C11-C24 range that Malassezia yeast can metabolize.

Learn more about Argania Spinosa Kernel Oil
Emollient, Skin Conditioning

Camellia Japonica Seed Oil comes from the Japanese Camellia plant. This plant is native to East Asia and known as "Tsubaki" in Japanese.

Camellia Japonica Seed Oil is rich in oleic acid. This makes it a great emollient. Emollients help soften and soothe the skin by forming a barrier. This barrier traps moisture within, keeping your skin hydated.

Masking, Perfuming, Skin Conditioning

This ingredient is also known as olive oil. It has been used in skincare for centuries and science largely backs up its reputation as a nourishing emollient.

The main components of olive oil are oleic acid (55-83%), linoleic acid (3.5-20%), and palmitic acid (7-20%). Oleic acid promotes skin regeneration and helps regulate inflammatory responses.

Squalene is also naturally present in olive oil and exhibits moisturizing and antioxidant properties.

The polyphenols in olive oil also show anti-aging promise; one clinical study found a measurable improvement in skin appearance after 30 days of topical serum use.

Just be aware that applying olive oil directly to skin can weaken the barrier and cause redness. One study with volunteers found even people without sensitive skin experienced a significant reduction in stratum corneum integrity and induced mild erythema.

It's best to use this ingredient as part of a carefully crafted formula (instead of putting it on skin directly from the bottle).

Because it has a 2-3 on the comedogenic scale, it is a moderate risk for acne-prone skin. However, the overall formulation of a product matters more than a few ingredients with comedogenic ratings.

This ingredient may not be fungal acne safe because of the oleic and palmitic acid content. These fall within the C11-24 fatty acid range that the Malassezia yeast can metabolize to grow.

Overall, olive oil is a well-studied and nourishing skincare ingredient.

Learn more about Olea Europaea Fruit Oil
Moisturising, Skin Conditioning, Smoothing

We don't have a description for Prunus Domestica Fruit Extract yet.

Skin Conditioning, Skin Protecting, Tonic

This ingredient comes from the leaves of the evergreen tea, Eriobotrya japonica (loquat). It has skin conditioning and protecting properties.

The leaves of this tree are rich in antioxidants that help soothe and protect the skin from oxidative stress.

Some studies suggest this ingredient may inhibit pigment production in the skin to help even out skin tone.

Learn more about Eriobotrya Japonica Leaf Extract

This leaf extract comes from the Asian mugwort. It has antioxidant and anti-inflammatory properties.

Fun fact: This flower is part of the sunflower family.

Skin Conditioning

Houttuynia Cordata Extract is more commonly known as Heart Leaf, Fish Mint, or Chameleon plant.

The components found in Heart Leaf give it antioxidant, hydrating, antimicrobial, and anti-inflammatory properties.

Heart Leaf is rich in flavonoids such as quercetin, apigenin, and more. It also contains polysaccharides, the most common type of carbs in food.

Flavonoids have been shown to be effective antioxidants. They help neutralize free-radical molecules. Free-radical molecules are unstable molecules that may damage our skin cells and DNA. The flavonoids in Heart Leaf also help soothe the skin.

Polysaccharides are naturally found in our skin. They play a role in hydrating and repairing the top layer of skin. The polysaccharides in Heart Leaf help moisturize our skin.

Studies show decanoyl acetaldehyde, a component of Heart Leaf oil, is effective at killing bacteria.

The name 'Fish Mint' comes from the herb's natural fishy smell. Is is native to southeast Asia and used throughout the continent for traditional cooking and medicine.

Learn more about Houttuynia Cordata Extract
Humectant, Skin Conditioning

We don't have a description for Bidens Pilosa Extract yet.

Skin Conditioning

We don't have a description for Olea Europaea Flower Extract yet.

Polyhydroxystearic Acid is a vegetable-derived soft wax made from castor oil. It's an emulsion stabilizer, thickener, and film former.

You'll likely see it in sunscreens because it helps disperse pigments and UV-reflecting minerals like titanium dioxide and zinc oxide evenly.

Depending on the concentration, it can drastically change the texture of a product from pasty solid (like lipstick) to sprayable liquid.

The CIR Expert Panel for Cosmetic Ingredient Safety has concluded this ingredient to be safe in cosmetics. The highest reported use concentration is 14.2% in lipsticks.

Learn more about Polyhydroxystearic Acid
Skin Conditioning, Solvent

Pentylene Glycol (1,2-pentanediol) is a multitasking little diol with three main roles in a formula:

Research on alkanediols (the family pentylene glycol belongs to) show they work by disrupting microbial cell membranes. This disruption helps the primary preservative system in a product work more effectively at lower doses.

On the safety side, the Cosmetic Ingredient Review Expert Panel has concluded this ingredient to be safe as used in current cosmetic practices + concentrations.

Typical use levels in a formula run about 1-5%.

Learn more about Pentylene Glycol
Emollient, Humectant, Skin Protecting

Aluminum Hydroxide is a form of aluminum. It can be naturally found in nature as the mineral gibbsite. In cosmetics, Aluminum Hydroxide is used as a colorant, pH adjuster, and absorbent.

As a colorant, Aluminum Hydroxide may add opacity, or reduce the transparency. Aluminum hydroxide is contains both basic and acidic properties.

According to manufacturers, this ingredient is an emollient and humectant. This means it helps hydrate the skin.

In medicine, this ingredient is used to help relieve heartburn and help heal ulcers.

There is currently no credible scientific evidence linking aluminum hydroxide in cosmetics to increased cancer risk.

Major health organizations allow the use of aluminum hydroxide in personal care products and have not flagged it as a carcinogenic risk at typical usage levels.

Learn more about Aluminum Hydroxide
Humectant, Masking, Skin Conditioning

Butylene Glycol (or BG) is used within cosmetic products for a few different reasons:

Overall, Butylene Glycol is a safe and well-rounded ingredient that works well with other ingredients.

Though this ingredient works well with most skin types, some people with sensitive skin may experience a reaction such as allergic rashes, closed comedones, or itchiness.

Learn more about Butylene Glycol
Antimicrobial, Astringent, Masking

This ingredient is also called ethanol or ethyl alcohol. It is denatured, meaning made undrinkable for cosmetic use.

In formulas, it:

Is it bad for your skin?

The answer comes down to concentration. Patch and wash studies have found highly concentrated alcohol-based hand rubs (60-100%) cause less barrier disruption than washing with a basic detergent like SLS. The only measurable effect in these studies was a temporary dip in skin hydration.

Concentrations below 12-15% in leave-on cosmetics is generally well-tolerated. Concentrations above start to see increased transepidermal water loss (TEWL) and reduced hydration.

In concentrations about 58%, it creates temporary channels in your skin's lipid layers to become more permeable and allow other ingredients to slip through easily.

This ingredient can be up to 80% of the formula in alcohol-based perfumes.

Overall, this ingredient is probably harmless if found lower down an ingredients list but worth side-eyeing if it's high up (especially if your barrier is already struggling).

Alcohol can worsen dry skin, eczema, and oily skin, especially at higher concentrations. This is because it can increase transepidermal water loss and decrease hydration to disrupt the skin barrier.

According to the National Rosacea Society based in the US, you should be mindful of products with these alcohols in the top half of ingredients.

True allergic contact dermatitis to ethanol is uncommon, but be sure to patch test if you have dry or sensitive skin.

Learn more about Alcohol
Cosmetic Colorant

Mica is a naturally occurring mineral used to add shimmer and color in cosmetics. It can also help improve the texture of a product or give it an opaque, white/silver color.

Serecite is the name for very fine but ragged grains of mica.

This ingredient is often coated with metal oxides like titanium dioxide. Trace amounts of heavy metals may be found in mica, but these metals are not harmful in our personal products.

Mica has been used since prehistoric times throughout the world. Ancient Egyptian, Indian, Greek, Roman, Aztec, and Chinese civilizations have used mica.

Learn more about Mica
Abrasive, Absorbent, Skin Protecting

Talc is a clay mineral. It helps absorb moisture and improve the texture of products. Like other types of clay, Talc can have a slight exfoliating effect on skin. Talc can be added to increase the volume of products.

Some Baby powders are made by combining talc with corn starch. The word "talc" comes from Latin and originates from Arabic. Talc is a mineral commonly found throughout the world.

If you have any concerns about using talc, we recommend checking out the FDA's official page.

Learn more about Talc

This ingredient is a combination of red, black, and yellow iron oxide pigments. This combination of colors is usually found in foundation, because it results in a "skin" color.

The EU typically uses CI numbers for colorants when applicable, such as CI 77489. In the US, iron oxides are regulated as color additives and "iron oxides" is the most commonly used name in US cosmetic practice.

A 2021 paper looked at skincare formulations containing iron oxides and found that they reduced transmission of blue light when measured optically. In simple terms, the pigment particles helped block or scatter part of the visible light spectrum in lab testing and the authors suggest this could translate into better protection against blue-light-related skin effects.

There is also clinical and experimental research showing that tinted products containing iron oxides can reduce visible light-induced pigmentation:

Please note, whether a product reduces visible or blue light depends on things like:

In the EU's CosIng database, iron oxides are only listed as a colorant. CosIng groups ingredients by their main cosmetic role, such as colorant, preservative, or UV filter.

Though studies say iron oxides can "attenuate blue light", they're describing an optical property and not an officially recognized cosmetic function.

So CosIng isn’t contradicting the research. It’s just classifying iron oxides by what they officially are: pigments that add color.

Learn more about Iron Oxides

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Where it's from

24h Cosme is a Japanese brand

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40 SPF Rating

With an SPF rating of 40, this product protects against 97.5% of UVB rays

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· Updated May 1, 2025 Added by ktmgiu