Tannic Acid

What it is

Tannic acid is a mixture of gallotannins extracted from plant galls, oak bark, sumac or tea. It binds readily to proteins, which is what produces the tight, drawing sensation on skin and in the mouth, and it is also a capable antioxidant. In masks it is used for a temporary pore-tightening and mattifying effect and to add polyphenol content, not to shed dead cells.

What it does well

• Gives a temporary tightening, mattifying feel

  Its protein-binding astringency briefly contracts the skin surface so pores look smaller. The effect is cosmetic and short-lived, and does not change pore size.

  Limited evidence

Worth knowing

• Astringency can be drying, and it discolours formulas

  Repeated use on already dry skin can leave it tight and rough. Tannins also oxidise to brown, which is why tannin-rich masks often darken over time, a cosmetic change, not spoilage.

  Matters most toPeople with dry or sensitive skin.

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