What it is
Sodium oleate is a classic fatty-acid soap formed by neutralizing oleic acid with sodium hydroxide. It acts as an anionic surfactant and emulsifier, helping to combine oil and water and to cleanse, and is sometimes generated in situ when a formula contains both oleic acid and an alkali. In sunscreens it can help emulsify the oil phase and stabilize the formula at low levels.
Safety & warnings
As a soap-type anionic surfactant, sodium oleate is alkaline and can be mildly irritating or stripping at higher levels in leave-on products, though it is generally well tolerated at the low levels used as an emulsifier. It is not a recognized fragrance allergen.
Origin & sourcing
Sodium oleate is the sodium soap of oleic acid; oleic acid is a fatty acid found in many plant and animal oils and can also be produced synthetically.
Questions everyone asks
Is sodium oleate a soap?
Yes. It is the sodium soap of oleic acid and acts as an anionic surfactant and emulsifier.
Why is it in a sunscreen?
It typically helps emulsify the oil phase and stabilize the formula, and is used at low levels for that purpose.