What it is
Steareth-2 is made by reacting stearyl alcohol with about two units of ethylene oxide, giving a nonionic surfactant with a relatively low HLB value. Because of this low HLB it functions mainly as the oil-loving partner in an emulsifier system and is frequently paired with a higher-ethoxylated steareth such as Steareth-21 to produce stable oil-in-water creams and lotions. It helps blend oily UV filters and emollients smoothly into the water phase.
Safety & warnings
Steareth-2 is generally well tolerated at typical use levels. As an ethoxylated ingredient it may contain trace 1,4-dioxane, which responsible manufacturers control through purification; it is not a recognized fragrance allergen.
Origin & sourcing
Synthetic, produced by ethoxylating stearyl alcohol; the starting fatty alcohol can be of plant or petrochemical origin.
Questions everyone asks
Why is Steareth-2 paired with Steareth-21?
Steareth-2 has a low HLB and Steareth-21 a high HLB, so combining them lets formulators tune the overall emulsifier balance to stably emulsify a given oil phase.
What does the 2 in Steareth-2 mean?
It indicates the average number of ethylene oxide units attached to the stearyl alcohol; a low number means lower water solubility and a more oil-loving emulsifier.