Tips on Ingredients
• Products and makeup that are “preservative-free” often attract bacteria sooner than those with preservatives, which can prolong shelf life, so be vigilant about replacing those on a regular basis.
• Products with water as one of the first ingredients and “all natural”products are typically contaminated sooner. Always read the labels carefully.
• Ingredients like vitamin C and retinol will degrade in the sunlight, so it is best to store them in a cool, dry place (a good idea in general). If you’re storing these products in the bathroom, make sure they’re placed away from the shower.
• Any product that has an SPF value or another type of “active” skin-care ingredient should have an expiration date on it. Using a product past its expiration date doesn’t necessarily mean it will harm you, but it does mean you will not get the full effectiveness of the formula.
 

Tips on Packaging
• Face oils should be packaged in dark-colored glass or opaque packaging, which protects the properties of the oil from sunlight.
• Products with one-way evacuation like a pump or tube have a longer shelf life than jars, which can become contaminated much more quickly when using your fingers for application. (VIOLET Says: Do not throw out the little spatula that comes with the jars of cream. Using them can extend the life of the product.) 
• The Period After Opening symbol (PAO) is a number followed by an M, and it is mandated on most European skin-care products. The digits that follow the M dictate the number of months a product stays fresh from the time you unseal or open it. Once you start using the product, make a note of this time frame on your calendar. Better yet, set a reminder on your phone.

Tips on Ingredients
• Products with zero water content (considered anhydrous) pose little risk of bacterial contamination.
• Smell and discoloration can be telling of product viability. Trust your nose and note if the formulation has separated or dried out.
• The visual cues and performance of the product are the best indicators — always take note of smell, consistency and distribution of color.

Tips on Packaging
• One-way evacuation applicators and tubes can prolong the life of your foundation because there is less risk of air affecting the formulation or fingers introducing bacteria.
• Brush-tip concealers and foundation pens use synthetic brush hair that is antimicrobial. Engineered to not allow any product back in, these products can tend toward a longer lifespan.
• Items that rely on sponges, fingers and brushes for application can introduce bacteria into the product, but developers often anticipate that and adjust formulas to be more resistant to microbes.

Tips on Ingredients
• Most lipsticks are formulated without water, which is where bacteria most likes to grow. Pay attention to discoloration, changes in smell and filmy application.
• The ratio of wax to oils in lipsticks is greater than in lip gloss. More wax means bacteria has a harder time penetrating the entire tube.
• Lip glosses should be replaced more often because application requires pumping the wand to get product — similar to mascara. The introduction of air compromises the product more quickly.

Tips on Packaging
• Tube lipsticks are an industry standard and those that boast the longest shelf life. As in a waxed-based eyeliner pencil, bacteria lives on the surface of lipsticks, so you can scrape or wipe off the top layer to remove the bacteria.
• Lip gloss packaged in tubes with a wand or pots should be kept for a shorter time than single-evacuation applicators like a tube applied directly to the lips.
• Whether it’s a tube or pot, lipsticks and glosses will be exposed to bacteria from either your lips or fingers. With that in mind, preference on form versus length of time you can use it can help you determine when to toss it.

Tips on Ingredients
•  Divide eye makeup by those containing water and anhydrous (no water) products, since mascara and liquid liner need to be replaced more often than powder shadows.
• Waxed-based eyeliners can last longer than liquid liners, which are more prone to bacteria. Regularly sharpen your liner after each use to reveal fresh, new product.
• Bacteria can spread more quickly and be more harmful in these products that come into contact with your eyes. Take care never to share products or avoid use if you have any eye infection.

Tips on Packaging
• Pumping your tube mascara to coax more product can dry it out faster and introduce more susceptibility to bacteria.
• Shadow powders should remain in a tightly sealed container to avoid discoloration over time.
• Twist-up eyeliners keep the product protected and keep risks of contamination at bay. A regularly sharpened wax-based eyeliner pencil has the same benefits. A clean applicator goes a long way.

Tips on Ingredients
• Five-free lacquers and polishes (toxic-free and formulated without five harsh chemicals) tend to degrade quicker in the same way all-natural skin-care products will.
• More standard formulas contain specific ingredients that will preserve the color and consistency over time, prolonging the life of the polish.

 Tips on Packaging
• The same rules apply here as they do with foundation. With packaging uniform across brands, store polishes away from sunlight and extreme temperatures.
• Before application, take the polish brush out to check for odors, discoloration or when the formula thickens or hardens over time. Regular exposure to air and heat can quicken this decline.