The answer I’m supposed to give is: after every use. But to quote a wise woman from one of the greatest viral videos of all time: “Ain’t nobody got time for that!” This is one of the beauty admin things I’m terrible at; I often leave them until a makeup artist friend intervenes in disgust, or after trying to apply a brown eyeshadow and it comes out blue because that’s what I used the brush for previously. Dirty brushes collect sebum and dead skin, and thus become a breeding ground for bacteria that could cause rashes and acne. The American Academy of Dermatology also says that “Dirty makeup brushes can cause an infection, E coli or a staph infection, which can be very serious.” TERROR! I don’t think I’ve ever washed my brushes so fast; I even stopped writing this column to do just that. They recommend washing them every seven to 10 days, but I’m now on a more realistic bi-monthly rotation, and in between I use a MAC Brush Cleanser spray. So how do you wash them properly? Use hand soap or washing-up liquid on the bristles, and rinse the tips under lukewarm water until the water runs clear. Then lay your brushes flat (never upright as it’ll dissolve the glue holding the bristles together) to dry on a towel, with the tips hanging off the edge of a table top. Consider us both schooled on this one, my friend.