Naked Sundays Mineral Summer Stick SPF 50

Naked Sundays Mineral Summer Stick SPF 50

This mineral sunscreen covers the full UV range and blocks ~98% of UVB at SPF 50.

We independently verify ingredients, backed by peer-reviewed research. Suggest an update.

Save

What's inside

Key Ingredients

Benefits

Concerns

Ingredients Explained

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
Masking, Perfuming, Skin Conditioning

This ingredient is also known as castor oil. It is a skin conditioning ingredient.

The star component of castor oil is ricinoleic acid, an unusual fatty acid that makes up ~80-92% of its composition.

In skincare, it is an emollient that dries down to a solid film with water-binding properties. This helps keep skin hydrated and helps reduce transepidermal water loss (TEWL).

A 2026 dermatology review pulls together its broader uses:

Human clinical testing found this ingredient to be non-irritating and non-sensitizing.

Because castor oil contains fatty acids in the C11-24 range, this ingredient may not be fungal acne safe.

At this time, the literature does not support castor oil in regrowing hair. A 2022 systematic review found no strong evidence that it supports hair growth and only weak evidence that it improves hair shine.

Castor oil itself carries "perfuming" and "masking" function tags according to the official CosIng database. This is because of its mild odor and odor-dampening properties.

Learn more about Ricinus Communis Seed Oil
Antimicrobial, Emollient, Skin Conditioning

C12-15 Alkyl Benzoate is a lightweight emollient made by combinig benzoic acid with fatty alcohols that are 12-15 carbons long.

In cosmetics, it plays several roles:

The Cosmetic Review Expert Panel has concluded the alkyl benzoate group to be safe as used in cosmetics; it wasn't found to be a skin irritant and unlikely to be absorbed due to its low water solubility.

This report recorded almost 1000 reported uses with concentrations up to 59% in leave-on products but your cosmetics will typically use 0.5-15% depending on the product.

It's often called a "SPF booster": this is because it keeps UV filters properly dissolved and evenly distributed to support a sunscreen's performance. It doesn't actually raise SPF on its own.

Overall, this ingredient is well tolerated.

This ingredient is fungal acne safe because it is an ester of benzoic acid.

Think of this ingredient as two parts stuck together: an oily part and an acid part. Malassezia only gets a meal when it can snip off a fatty acid to eat. With C12-15 Alkyl Benzoate, the acid part is benzoic acid, which isn't a fatty acid and which the yeast can't use as food.

Benzoic acid is actually used as a preservative to stop yeast from growing.

The oily part is a blend of C12-15 fatty alcohols but fatty alcohols in this size range can support only a little Malassezia growth (mostly for one species of Malassezia as well).

In the ingredient, those alcohols stay locked inside the molecule. The yeast can only reach them by snipping the benzoate bond, and that type of bond is harder for it to cut than a normal fatty bond.

So not much gets released. And whatever does get snipped comes packaged with benzoic acid, which discourages yeast growth.

Learn more about C12-15 Alkyl Benzoate
Emollient, Skin Conditioning

Coco-Caprylate/Caprate is a lightweight ester created from coconut oil fatty acids, caprylic acid, and capric acid.

It is an emollient that helps soften skin and reduce transepidermal water loss (TEWL). What sets it apart from heavier emollients is its ultralight, non-greasy feel.

Once applied, this ingredient dries down quickly and leaves a dry, silky finish behind. This also helps improve spreadability and texture.

This ingredient has an excellent safety-record and is non-irritating.

Typical concentrations for cosmetics range from 0.5-62%.

Research on Malassezia growth found no growth on fatty acid esters with chain lengths shorter than 12 carbons (it prefers C11-24).

Since Coco-Caprylate/Caprate is built on C8 and C10 fatty acids, it is out of the range that Malassezia metabolizes, and therefore safe for fungal acne.

Learn more about Coco-Caprylate/Caprate

Euphorbia Cerifera Wax (aka candelilla wax) is a vegan stand-in for beeswax. It is a plant-derived wax that functions as an astringent, emulsion stabilizer, film-former, and skin conditioner.

On skin, it forms a protective barrier that helps lock in moisture while it enhances product stability, prevents separation, and helps color last longer in makeup.

This ingredient is generally safe for use in cosmetics with one nuance: some grades of candelilla wax can naturally contain benzyl alcohol at concentrations high enough to require declaration under EU labeling rules. This isn't a concern for most people but relevant for those with fragrance sensitivities.

Candelilla wax contains fatty acids (mainly C31) and wax esters that can be used by the Malassezia yeast, so this ingredient may not be fungal acne safe.

You might see Euphorbia Cerifera "Cera" instead of "wax". This is because some brands, databases, or labels use it interchangeably; they're the same ingredient.

Learn more about Euphorbia Cerifera Wax

Copernicia Cerifera Wax comes from a palm tree native to Brazil; another name for this ingredient is Carnauba Wax.

This ingredient is used to thicken texture and also leaves behind a film when applied.

Fun fact: This wax has the highest melting point of all natural waxes and low solubility.

Learn more about Copernicia Cerifera Wax
Emulsion Stabilising

Ceresin is a wax derived from ozokerite. It is an alternative to beeswax.

The most common process of creating ceresin is by using heat and sulfuric acid.

Emollient, Masking, Skin Conditioning

Theobroma Cacao Seed Butter comes from the Theobroma cacoa, or Cacao tree. Cacao trees are native to tropical landscapes.

Like other plant butters, Cacao seed butter is an emollient. Emollients help soothe and soften your skin. By creating a barrier to trap moisture in, emollients help keep your skin hydrated.

Cacao seed butter contains antioxidants known as polyphenols. Antioxidants help fight free-radical molecules by stabilizing them. Unstable free-radicals may cause damage to your skin cells. Antioxidants may help with anti-aging.

Theobroma Cacao Seed Butter can be bad for acne prone skin.

Learn more about Theobroma Cacao Seed Butter

Polyglyceryl-3 Polyricinoleate is a plant-derived emulsifier made by combining glycerin and ricinoleic acid.

It works well for giving buttery lip balms and low-viscosity water-in-oil emulsions a non-greasy and pleasant skin feel.

Typical concentrations range from 0.1-3%.

This ingredient is mild and non-irritating in nature.

Because it is derived from ricinoleic acid, this ingredient may not be fungal acne safe. Ricinoleic acid is an unsaturated fatty acid that the Malassezia yeast can metabolize.

Learn more about Polyglyceryl-3 Polyricinoleate
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
Antioxidant, Skin Conditioning

Tocopheryl Acetate is a stable, shelf-friendly form of vitamin E.

Formulators love it because plain vitamin E oxidizes quickly once it hits air. This acetate version stays stable and resists going off, helping to extend a product's shelf life.

It's actually inactive on its own and works like a slow-release "storage" form; the enzymes in your skin called esterases gradually convert it into active vitamin E over time.

One in vivo study showed 5% of the acetate in the living layer of the epidermis converted to vitamin E after 5 days of application. This study also found the skin gained protection against UV damage even though the conversion was slow and small.

Once converted, vitamin E acts as a skin's main fat-soluble antioxidant that fights free radicals to protect skin from damage.

Topical vitamin E generally boosts the skin's photoprotection, and it reduced UV-damage in animal models.

This ingredient has some brightening potential but it's more of a prevention ingredient than spot-fader. Cell studies show it can slow down melanin production but it's worth noting that it's not the most powerful brightener out there.

Overall, it has a pretty solid safety profile and has been found to be non-irritating and non-comedogenic. Allergic reactions may happen but stay rare due to how widely the ingredient gets used.

The concentration will vary depending on the formula; industry data shows 0.1% in baby lotions, 3% in lipsticks, and 5% in foot powders. You can also find this ingredient at 100% in a pure vitamin E oil.

Most leave-on skincare keeps it at the lower end, often between 0.5-1%.

Learn more about Tocopheryl Acetate
Skin Conditioning

This ingredient is also known as Avocado oil. It's the cold-pressed oil from the flesh of the avocado fruit packed with fatty acids (mostly oleic acid).

The rich fatty acid profile allows it to function as a skin conditioning agent and emollient; it helps soften and smooth skin while reducing water loss.

Preclinical research has found that topical avocado oil increased collagen synthesis and reduced inflammation during wound healing, giving it some skin-repairing credibility.

The unsaponifiable fraction of the oil is also interesting: studies on avocado unsaponifiables showed that it helped skin produce more collagen and other structural compounds that support healing.

The CIR Expert Panel has found this ingredient to be non-irritating in formulations.

It's a great ingredient for dry or compromised skin. Just know it may not be fungal acne safe. This is because the oleic acid content falls within the range that Malassezia can use as a food source.

Learn more about Persea Gratissima Oil
Cosmetic Colorant

CI 77492 is also hydrated iron III oxide. It's sole purpose is to give a yellow hue to products.

Iron III oxides are classified as inorganic chemicals for coloring.

Synthetically created CI 77492 is considered safer than those naturally found. This is because the synthetically created version may contain less impurities. Iron oxides are generally non-toxic and non-allergenic.

Learn more about CI 77492
Cosmetic Colorant

Ci 77491 is also hydrated iron III oxide. It's sole purpose is to give a red/pink hue to products.

Iron III oxides are classified as inorganic chemicals for coloring.

Synthetically created Ci 77491 is considered safer than those naturally found. This is because the synthetically created version may contain less impurities. Iron oxides are generally non-toxic and non-allergenic.

Learn more about CI 77491

Reviews

3.0
Overall rating
5
4
3
2
1
What people say
Heavy 100% Oily 100% Sticky 100%
1 review

Where it's from

Naked Sundays is a Australian brand

Australian flag

50 SPF Rating

With an SPF rating of 50, this product protects against 98.0% of UVB rays

SkinSort Icon
Verified by SkinSort

We're dedicated to providing you with the most up-to-date and science-backed ingredient info out there.

The data we've presented on this page has been verified by a member of the SkinSort Team.

Read more about us

· Updated May 27, 2026 Added by RosyPal