Remember that saying "oil and water don't mix"? Well, it applies to your beauty products, too. When a Sugar staffer presented this lip gloss to me, I put on my thinking cap and checked the label. Since she'd only owned this product for a couple weeks, it wasn't technically time for tossing.

After forgetting the gloss in a hot car for a few hours, she found these results. Think you know why it happened? Find out when you read more.

Even though water wasn't listed as an ingredient, my research revealed that many gloss bases include an oil-in-water emulsion that makes up the gel-like substance. The very first ingredient, hydroxylated lanolin, actually comes from heating lanolin with water. Additionally, ingredients with different densities like other heavy oils and waxes can be whipped up into a mixture that can splits over time or temperature. One that's not water soluble is petroleum jelly (also called petrolatum) and is the second ingredient found in this lip gloss. I'm betting the heat prompted the separation process leaving that on top of the rest of the ingredients. Has this ever happened to you?