Bobbi Brown Long-Wear Smudge-Proof Gel Eyeliner Versus Bobbi Brown Long-Wear Smudge-Proof Gel Eyeliner

Due to its structure as flat, plate-like crystals that stack like tiles, it feels silky and sticks to skin well. This also makes it very chemically stable and insoluble under normal skin conditions (this just means it sits on top of skin rather than going into it).

It has an interesting quirk: it slowly goes gray in sunlight and the graying is partly reversible in the dark.

At this time, there's no legal cap on how much a brand can use. Both the FDA and the EU permit it without restriction so real-world concentration levels come down to formulation:

Allergy risk is low as well since it's insoluble and doesn't release free metal ions into skin. True allergic contact dermatitis to it is rare enough that there's very little published cases.

However, mineral makeup users do report itching or stinging. The leading explanation for this is irritation from those stiff platelet crystals rubbing on skin (also more likely with heavy, high-percentage loose mineral powders) rather than an immune reaction.

This ingredient shows up on a lot of "pore-clogging" lists but there's no real evidence behind that. It doesn't even have a comedogenic rating from an actual study; the numbers you'll find online come from blogs citing other blogs.

Some people still find it breaks them out. So if that's you, definitely trust your skin.

In the EU, both of these colors must be labeled as 'CI 77510'.

Ci 77891 is commonly found in sunscreens due to its ability to block UV rays.

Hectorite is a rare, white clay mineral.

Hydrogenated Polyisobutene is often used as a mineral oil replacement.

Isododecane's role as a solvent makes it a great texture enhancer. It spreads smoothly on skin and does not leave a sticky feeling behind. Isododecane also helps prevent color transfer in makeup products.

Isododecane is not absorbed into skin.

The chemical name for this ingredient is 2,2,4,6,6-PENTAMETHYLHEPTANE.

It plays well with most ingredients and is typically used at 0.1-1%. However, concentrations up to 50% have been reported in moisturizers.

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.

On a cellular level, it disrupts the cell membranes of microbes by poking holes that make the cell leak. This shuts down the chemical reactions the microbe needs to make energy so it can no longer survive.

Another perk of this ingredient is that it stays functional across a wide pH range (3-10).

You'll often see it paired with boosters like Ethylhexylglycerin; one study showed that a 1:9 ratio of Ethylhexylglycerin to Phenoxyethanol damages bacterial membranes as effectively as doubling the Phenoxyethanol concentration on its own.

Typical use concentrations range from 0.3-1% depending on the formula, and this ingredient is capped at 1% int the EU.

Safety-wise, the fear mongering does not hold up to the evidence. The EU's Scientific Committee on Consumer Safety and FDA consider it safe as a preservative at up to 1%, including for children of all ages.

Adverse systemic effects only showed up in animal studies at exposures roughly 200x higher than what people get from cosmetics. And despite its very widespread use, this ingredient is a rare sensitizer and allergic reactions are uncommon.

According to a manufacturer, it can blend seamlessly with silicone oils, such as Cyclopentasiloxane.