While many products have seasonal appeal – foundation that won’t sweat-off in the summer, cream blushes that moisturize dry, winter skin – waterproof mascara seems to be in-demand year-round, whether you’re looking for a formula that will stay-put during a snowstorm or a day at the beach.

But, while we all worship at the altar of waterproof mascaras, you may still be curious as to how the magical formula resists water so well.

“Waterproof mascaras do not contain water, and are free of ingredients that mix or dissolve with water,” industry expert Terry Van Liew told StyleList.com. “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.”

However, while some products promise a waterproof formula that will increase lash length and others vow to resist water and maximize volume, women who want it all may have to wait a bit longer.

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