Flat-top buffing brush

A flat-top buffing brush is a round, dense bundle of short fibres cut straight across, like a cylinder sliced off at the end, set on a long handle. The flat face meets the skin all at once, so foundation is pressed and polished in rather than painted on, and the result is smooth, fairly full coverage without the stripes a flat paddle brush can leave. Makers often sell it as a flat kabuki or a foundation buffer.

Its neighbours differ in small but useful ways. A kabuki is domed and squat, made above all for powder. A domed buffing brush has the same density with a rounded top, which slips more easily into the sides of the nose. A duo-fibre stippling brush can be flat-topped too, but its longer, sparser outer fibres dot product on for a sheerer finish. The flat-top is the one for coverage.

Density decides coverage. The more tightly packed the head, the more foundation it holds and presses into the skin, and the more it blurs; a looser flat-top leaves a lighter layer. Size decides speed. A broad head covers the cheeks and forehead in a few passes; a smaller one works around the nose, the eyes and a blemish, and some flat-tops come in mini versions for exactly that.

Choose synthetic fibre. It is not porous, so it does not drink liquid foundation, and it can be cut cleanly to shape, which is all a flat top is.^[1] Most flat-tops are made for liquids and creams, but not all: IT Cosmetics sells its #6 for loose and pressed powder foundations. The name on the handle matters less than the shape. ColourPop calls its small flat-top a stippling brush, Charlotte Tilbury calls its own a complexion brush, and Sigma, Glo, Bdellium and Graftobian all call theirs kabukis.

Match the brush to the foundation, too. Thin, fast-setting long-wear liquids need a brush that moves quickly, so work one area of the face at a time before the formula sets; thicker creams and sticks want a denser, firmer head that can push them into the skin; and with a powder foundation, a dense flat-top presses a fuller layer onto the skin than a loose powder brush can.

Dot foundation on the forehead, cheeks and chin, or put a little on the back of your hand and touch the brush to it. Press the flat face onto the skin first to set the colour down where it is needed, then buff in small circles, working outward so that the edges of the face get least. Keep the brush flat to the skin: tilting it drags the edge and leaves marks. If the foundation starts to look heavy, the brush is overloaded; wipe it on a tissue rather than pressing harder.

For a lighter finish, use less product rather than less pressure, and finish with a damp sponge pressed over the face. For more coverage, let the first layer set for a minute and buff a second, thin one only where it is needed, usually around the nose, the chin and any redness.

A dense brush holds on to what it is given. Clean a flat-top after each use with a brush cleanser or mild soap, working from the base of the fibres out, and dry it lying flat so the head keeps its edge and water does not reach the glue in the ferrule.

The flat-top belongs to the age of synthetic fibre. As late as 1997, a patent filed by DuPont could say that natural bristles such as goat hair had traditionally been used more than synthetic filaments of nylon or polyester in cosmetic brushes. The synthetics were stiffer, and those made fine enough to feel soft picked up too little product and simply “dump” it on the skin; DuPont’s answer was a softer filament, crimped to copy the wave of goat hair.^[2]

Two decades later the argument had turned. A patent filed in 2019 by the cosmetic-packaging maker HCT, granted in 2021, sets out the case for synthetic fibre: hair is porous and soaks up liquid and cream, “which may lead to clumping and waste”, while synthetic fibres are made to exact sizes, give a streak-free finish with liquids and can be cut to precise shapes. It names Taklon, nylon and PBT among the materials.^[3] Makeup artists put it more plainly. “We’ve mimicked real hair with synthetic bristles so you can use them with creams, powders and liquids – something you can’t do with real hair brushes,” the sisters behind the Real Techniques brushes told Marie Claire in 2015.^[4]

A flat, cut top is exactly what the older Japanese tradition avoids. Hakuhodo, the brush maker in Kumano, distinguishes a “brush”, made by trimming the tips of bundled hairs, from its own fude, shaped without cutting so that each hair keeps its natural tip. In 2023 it told Nippon.com that it was developing synthetic fibres, because concern for small animals had made hair other than that of livestock such as goats, horses and pigs harder to use.^[5] The flat-top is the other way of making a brush, and the one that liquid foundation called for.