Lash primer

A lash primer is the undercoat of the mascara world. It comes in a mascara-style tube with its own brush, goes on first, and is covered with mascara straight afterwards. Most are white or clear so that they disappear once covered; some are tinted brown or black. What is inside depends on the promise. Fine fibres add length and bulk, and tacky film formers hold those fibres down and give the mascara something to grip.^[1] Oils and waxes are often added too, and sold as conditioning.

It is easily confused with two neighbours. A lash serum is a treatment left on bare lashes, usually overnight, and sold on what it claims to do over weeks; a primer is a cosmetic that works only while it is worn. A mascara top coat goes the other way, painted over mascara to make a washable formula resist water. Of the three, only the primer changes what you see the moment the mascara goes on.

A white primer shows you exactly where it has been, which makes it easy to coat every lash, and means every lash then has to be covered, or the white shows through as a grey cast at the roots or the tips. It suits black mascara worn in more than one coat. A tinted primer, in brown or black, forgives a missed patch and can be worn alone for a light, defined look. A clear primer does the least visibly and suits fair lashes, brown mascara and brows. Black-tinted primers have become common, and several of the picks here are black rather than white.

The other choice is between fibres and none. A fibre primer adds the most length, but it adds it under a mascara that then has to hold the fibres down, and over a fibre mascara the combination can be heavy and shed. A fibre-free primer, sold on thickening or on holding a curl, is the gentler partner for a lengthening or curling mascara.

One coat, root to tip, combed through so that no clumps are left for the mascara to magnify. Then put on mascara before the primer has dried. Many primers are built around tacky film formers precisely so that the mascara will stick to them,^[2] and one left to set hard can flake under the next coat. Where a maker's instructions say to wait, follow them.

Keep both coats thin. A primer under a heavy volumising mascara is often one layer too many; its best partners are lighter lengthening and curling formulas, which gain the bulk they lack. Take it off with the mascara, using whatever the mascara needs: an oil-based remover for waterproof formulas, warm water for tubing ones. A primer sits against the eye as long as the mascara does, so the same rules apply to both: never share them, and throw both away after an eye infection.^[3]

Read the primer's own wear claim as well as the mascara's. A waterproof primer under a washable mascara makes the pair harder to take off than the mascara alone, so remove it as you would a waterproof one. A black-tinted primer worn by itself is a lighter look than mascara for days that need no more, and a clear one does the same for brows.

Colourless products for the lashes are older than coloured mascara in its modern form. Maybelline began with one. Lash-Brow-Ine, a scented cream of refined white petrolatum and oils with no colouring in it, was advertised in 1916 as nourishing the lashes and brows and promoting their growth, claims now considered untrue; in 1917 the company moved on to a coloured cake.^[4] Through the 1930s the larger houses sold lash creams beside their mascaras: Helena Rubinstein an Eye Lash Grower Cream, and Elizabeth Arden Ardena Stimulash, a black cream to be applied with or without mascara.^[5] Kurlash's recommended routine of 1936 gave its lash cream, Kurlene, a step to itself, and had it worn alone on the lower lashes while the colour went on the upper.^[6]

The primer as a separate first step belongs to the wand era. The historian James Bennett lists lash primers among the later refinements of the wand mascara, alongside hollow particles to thicken the film, polymers to curl it and waterproof top coats.^[7] A patent L'Oréal filed in November 2000 sets out the problem one kind of primer was meant to solve: fibres in mascara flaked and came away, making a second coat difficult. Its answer was a separate base of fibres and tacky film formers, applied first, to add volume and length and hold the fibres under the mascara.^[8] Who sold the first lash primer is a question the record does not answer well. It arrived as one refinement among several, not as an invention with a date.

The older promise has come back beside it. Products sold as lash growers are on sale again, now as serums, and in the United States a product that really did extend the growth phase of a hair would be a drug, not a cosmetic.^[5] A primer makes no such claim, and needs none: what it does is visible on the first morning, and gone that night.