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You wouldn't be without it on your wedding day, and many women won't leave the house without it during these muggy hot summer days.

Waterproof mascara can be both a blessing or a curse, depending on whether you're wearing or removing it.

So just how do the scientists get the stuff to endure on through the wettest of the elements?

"Waterproof mascaras do not contain water, and are free of ingredients that mix or dissolve with water. The formulas contain non-water soluble film formers that help with wear and create a film that fully coats lashes. Finding the correct film former is the most challenging and creative aspect of developing a waterproof mascara. It's generally the area that is patented by many major cosmetic companies," says Terry Van Liew, technical liason for the mascara-churning Lancôme labs.

But that's just the beginning of the formulation. Scientists have to make sure the waterproof technology doesn't interfere with making our lashes lush and sexy.

"Special thickeners help us create a product that doesn't separate. These thickeners will be thick as they sit but become thinner when disturbed," says Van Liew.

The primary culprit for "disturbing" the formula? That pumping action that women tend to unconsciously do when priming the wand for application. Next time, don't pump -- swirl instead. You'll pick up product without breaking down the formula.

"We also add pigments for color and an agent that helps the pigments disperse and blend uniformly into the mascara. We use packaging materials that hold the solvent so that it doesn't evaporate from the container," adds Van Liew.

And there's a reason why most formulas either lengthen or volumize -- yet can't do both exceptionally well.

"Wax is a key mascara ingredient and we use different waxes to create the mascara's end look. Some waxes lend themselves to building, while others lend themselves toward lengthening," reveals Van Liew.

All that magic, in one little tube. No wonder more women are rarely without it.