Occlusives
Definition
Occlusives are a category of moisturizing ingredients that work by forming a physical barrier on the skin's surface to prevent transepidermal water loss (TEWL). They essentially seal moisture in by creating a protective film that slows evaporation. Common occlusive ingredients include petrolatum (petroleum jelly, the most effective occlusive), dimethicone (a silicone), beeswax, squalane, mineral oil, lanolin, and shea butter. Occlusives are particularly beneficial for very dry or compromised skin, eczema, and in cold or dry climates where TEWL is accelerated. They are typically applied as the last step in a skincare routine, on top of humectants and emollients, to lock in all the hydration beneath. While some people worry that occlusives clog pores, most (especially petrolatum and dimethicone) are actually non-comedogenic. The concept of 'slugging' — applying a layer of petrolatum as the final step — has gained popularity for intense overnight barrier repair.
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