#Face Makeup: Toss-it time: Six months for liquids; two years for powders
Insider info: You increase the odds of bacterial growth — and, hence, of breakouts or irritation — when you repeatedly dip your brushes and fingers into liquid foundation. Also, as it ages, foundation can go on unevenly, creating a streaky, inconsistent finish. “Oils rise to the top, and the consistency thickens”. Powders present less of a problem because bacteria can’t grow where there’s no water. However, over time, powders with botanical ingredients like aloe or jojoba can become harder to blend and are more likely to crumble, as their trace amounts of water evaporate.
#Mascara Toss-it time: Three months
Insider info: “A mascara tube is a dark, wet environment — the perfect breeding ground for bacteria,” says New York City optometrist Andrea Thau, O.D. “Preservatives in a mascara only work for so long.” Dr. Thau knows from firsthand experience: She once developed a sty from a makeup artist’s mascara wand. Plus, three-month-old mascara is a non-performer. “It’s chalky and powdery, and any lengthening or thickening fibers often separate from the fluid, so the mascara stops going on in a smooth, even coat,” says makeup artist Cristina Bartolucci. To avoid hastening the demise of your mascara, never pump the wand — that pushes air into the tube, causing it to dry out faster. Instead, slowly draw out and twist the brush to scrape the tube’s interior and pick up product.
#Eyeliner and Eye Shadow: Toss-it time: Liquid eyeliners, three months; cream eye shadows, six months; pencil eyeliners and powder eye shadows, two years
Insider info: As they do with mascara, bacteria tend to flourish in liquid-eyeliner tubes, and the product dries out. Pencil eyeliners have a longer shelf life because you can create a fresh, clean surface each time you sharpen them. (Just be sure to regularly sanitize your sharpener with rubbing alcohol.) Powder shadows, like pressed powders, are less prone to contamination because they, too, lack water (if you wet them, toss after six months). But aging eye shadows have performance issues: They get packed down, making it harder to pick up pigment with your brush, says Bartolucci.