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Key Takeaways

• When your foundation oxidizes, it will turn darker in color. Opting for water-based skincare products can reduce the likelihood of this happening on your skin.

• Maintaining clean skin and using toner can help prevent your foundation from changing color during the day.

• Using a primer or setting spray acts as a barrier, reducing excess oil that can cause oxidation.

Ever walk out of your house feeling snatched only to look in a mirror hours later and wonder "What happened?!" Your flawlessly blended base mysteriously went from looking barely there to being definitely present. No, it's not your lighting or your eye prescription that needs revision. You can thank a fun little chemical reaction called oxidation for that cosmetic magic trick. When certain foundation formulas oxidize, they turn darker in shade (or even orange), flipping any perfected base to a very unwanted sepia-toned iteration. Many factors may cause your foundation to oxidize, from your skin's texture to the foundation formula. Luckily, there are things you can do to prevent this.

Read on for tips to prevent your foundation from oxidizing from board-certified dermatologist Joshua Zeichner, MD, cosmetic chemist Ginger King, and celebrity makeup artist Jamie Greenberg.

Meet the Experts

• Joshua Zeichner, MD, is the Director of Cosmetic and Clinical Research in Dermatology at Mount Sinai Hospital in New York City.

• Ginger King is a cosmetic scientist and the founder and CEO of Grace Kingdom Beauty, a cosmetic product development company.

• Jamie Greenberg is a celebrity makeup artist and Marshalls Beauty Expert.

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Make Sure Your Face Is Clean

This may seem like a no-brainer, but clean skin is healthy skin, and healthy skin is happy skin. Don't even think about applying foundation on an unwashed face (or worse—over yesterday's makeup). That's just asking for mismatched tones and a host of other problems. Be sure to cleanse your face each morning before applying any product or makeup.

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Don't Skip Toner

Swiping on a facial toner will help balance your skin's pH while absorbing excess oil your cleanser may have left behind. Zeichner explains that foundation oxidation "occurs more commonly in people who have oily skin," so eliminating excess oil as much as you can before application is an important first step to preserve the integrity of the color.

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Opt for Water-Based Skincare Formulas

Greenberg recommends opting for water-based or more naturally composed skincare formulas that are light on the oil while still being effective and hydrating. The more you can avoid oil-based products, the less you'll risk having your foundation change things up on you.

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Apply a Primer

According to King, foundations are made of pigments which are composed of iron oxides that can change colors as they react with particles in the air. "The oil on our skin or even in the formulation can also be oxidized and cause color change and rancid odor," she explains. Zeichner says that applying a primer to your skin pre-foundation may help absorb excess oil while creating a neutralized base layer for your foundation to bind to. King agrees, adding "It's about oil control so a mattifying primer is suitable or a setting spray."

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Choose the Right Foundation

Greenberg explains that not all foundations oxidize, and it's a matter of trial and error to find the right one for you and your skin in the first place. "Powder in general has less issues but powder also contains pigments like iron oxide," notes King. "With liquid formulas, oxidation is faster."

Byrdie Tip

"If you fall in love with a brand that oxidizes, you'd want to get that foundation in a shade lighter than you would normally wear," advises Greenberg. This will help balance the color change and make sure you're well-matched.

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Know What Ingredients to Look For

Regardless of what steps you take, some foundation formulas will be more prone to oxidation. As we previously mentioned, powder is less likely to oxidize than cream or liquid products, but certain ingredients can also make a big difference. "As far as the formula itself, the inclusion of antioxidants like vitamin E can help," says King.

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Use an Applicator, Not Your Fingers

Because the oils (and other contaminants) from your hands can cause reactions within your foundation bottle, you should use an applicator sponge or foundation brush and never your fingers or hands. Doing so will not only result in a smoother and more flawless application but, Zeichner says, will also preserve the integrity of your foundation and prevent oxidation.

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Blot Away Excess Oil

Blotting excess oil from your face is important before and after foundation application. If your face accumulates oils or starts to look greasy throughout the day, carry blotting papers. These will help absorb the oil as opposed to letting it sit on the skin's surface, which may affect the overall appearance and tone of your foundation. "If you have oilier skin, your foundation may [oxidize] faster in hot humid weather," adds King.

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Use a Setting Spray or Powder

Zeichner says spritzing on a setting spray or powder will help minimize oxidation, too: "It helps absorb excess oil to lower the risk of reaction with the pigment in the makeup," he tells us.

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Be Mindful of Shelf Life

Zeichner notes that the average shelf life of a foundation is around 12-18 months. So, if you don't use it daily, be mindful of how long it's been sitting on your shelf. If you use your foundation after the expiration date, it may appear dry and clumpy in texture and may also be more likely to oxidize due to oils separating and rising to the top.

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Store Correctly

In order to keep foundations from oxidizing before their use-by date, you'll need to ensure optimal storage. "Packaging-wise, keep away from heat, light, UV rays and air. So airtight components are good," says King. That means your humid, sun-filled bathroom counter may not be the best place for showcasing those pretty bottles.

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Clean Your Brushes

Take care of your trusty makeup brushes, and they'll take care of you. Keeping your brushes clean and sanitary ensures they're performing at their best and maintaining the integrity of your products. Excess oils left behind on brushes can lead to your foundation oxidizing, so prevent it by cleansing your brushes and sponges weekly or biweekly.

FAQ

• How do I know if my foundation will oxidize?

  Foundations that are made with oil or oil-based are more likely to cause your foundation to oxidize. Look for foundations that are water-based formulations, as these are less likely to oxidize.

• What causes foundation to oxidize?

  Most of the time, foundation oxidizes because your makeup combines with the oils in your skin, causing your foundation to oxidize or deepen in color.

• How can I stop my foundation from oxidizing?

  If you find your brand new foundation is oxidizing, you'll want to try and use oil-free products and set your face with powder to start. If your foundation is looking a bit old and the oil and color have started to separate, it's best to toss it out.