Alastin HydraTint Pro-Mineral Sunscreen SPF 36 Versus Alastin SilkSHIELD All Mineral Sunscreen SPF 30 with TriHex Technology

When applied to the skin, ectoin helps bind water molecules to protect our skin. The water forms a sort of armor for the parts of our skin cells, enzymes, proteins, and more.

Besides this, ectoin has many uses in skincare:

A study from 2004 found ectoin to counteract the damage from UV-A exposure at different cell levels. It has also been shown to protect skin against both UV-A, UV-B rays, infrared light, and visible light.

Studies show ectoin to have dual-action pollution protection: first, it protects our skin from further pollution damage. Second, it helps repair damage from pollution.

In fact, ectoin has been shown to help with:

Fun fact: In the EU, ectoin is used in inhalation medication as an anti-pollution ingredient.

Ectoin is a highly stable ingredient. It has a wide pH range of 1-9. Light, oxygen, and temperature do not affect this ingredient.

The chemical name for this ingredient is Tetrahydromethylpyrimidine Carboxylic Acid.

According to one study, it is an HA booster, antioxidant, and anti-irritant.

In this study, this ingredient was able to stimulate higher hyaluronic acid levels of the dermal and epidermal layers on a skin-like model. Hyaluronic Acid is a humectant, which means it helps attract moisture to your skin. Humectants help keep skin hydrated.

As an antioxidant, Hydroxymethoxyphenyl Decanone is able to fight off damage from free-radical molecules.

This is due to how structurally similar it is to what your skin already produces.

Though it is mostly an emollient that helps soften and hydrate skin, it also has some humectant and occlusive action. Humectants help the skin retain moisture while occlusives seal it in, making squalane a triple-threat moisturizer.

Research shows it has antioxidant capabilities that help protect against stressors like UV exposure, specifically UVA induced oxidative stress. This study also found that it supports collagen biosynthesis in human dermal fibroblasts.

No clinical study has reported significant adverse effects and irritation reactions are very rare from this ingredient (even at 100% concentration).

Overall, it's a fantastic ingredient for hydration and is suitable for all skin types.

This depends on the source. Squalane can be derived from both plants and animals. Most squalane used in skincare comes from plants.

Please note: the source of squalane is only known if disclosed by the brand. We recommend reaching out to the brand if you have any questions about their squalane.

Read more about squalene with an "e".

Though squalane is often called an oil, it’s technically not one. It is a hydrocarbon, meaning it is only made of carbon and hydrogen. True oils are triglycerides and made of fatty acids and glycerol.

The term “oil-free” isn’t regulated so companies can define it however they want. Some exclude all oils, while others just avoid mineral oil or comedogenic oils.

Squalane has a comedogenic rating of 1 from the original 1972 study that tested raw ingredients under occlusion on rabbit ears. This system is not standardized or peer-reviewed, and using the raw ingredients is very different from how diluted cosmetic formulations are used on human skin.

A comedogenic rating of 1 means it is "unlikely to clog pores" according to the original rating system.

The overall formula of a product matters more than the individual ingredients on whether or not it will cause clogged pores.

Topically applied tocopherol has been shown to protect against UV damage by ramping up the skin's own natural defense enzymes.

It also acts as a skin conditioning agent; some studies show that regular topical use can improve the skin's water-binding capacity over 2-4 weeks.

This ingredient is especially loved for being a team player. When combined with Vitamin C, the photoprotective effect of both ingredients roughly doubles and the combo also helps reduce UV-induced DNA damage.

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.

In formulations, it also serves as a stabilizer that helps protect other oxidation-prone ingredients from degrading.

Concentrations usually range from 0.1-1% in most leave-on products.

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.