butylene glycol
what it is
A small, clear humectant liquid — INCI name Butylene Glycol — made by fermentation or conventional synthesis. It attracts and holds water, and it doubles as a solvent for other ingredients.
why we use it
It hydrates with less tack than glycerin alone, lightens the feel of the formula, and helps the sunscreen's water phase stay stable through temperature swings. A product sold from Delhi spends time in courier vans in June; our formulas are built with that in mind.
where you'll find it
In our mineral sunscreen (SPF 50+ PA++++), in the hydrators group (4.85% total). Per-ingredient percentages within the sunscreen groups are not yet published; the group totals are exact.
evidence
A well-established humectant and solvent with a long formulation record — solid evidence for its function, if less exhaustively studied than glycerin.
safety
The word glycol makes some people think of antifreeze; butylene glycol is not ethylene glycol and does not share its toxicity. It is assessed as safe in cosmetic use, with low rates of irritation.