On Sunday afternoon we received a little bit of an education from Tom Pecheux, who was handling the beauty side of things backstage for Derek Lam. He was demonstrating how to use an Estée Lauder cream eyeshadow to bring down the models' lip color when we inquired as to the type of brush in his hand.

“You need to use a synthetic brush!” he exclaimed. “If you use a brush with a cream-based product it must be synthetic, not a natural hair. If it’s a cream blush or cream eyeshadow or lipstick or foundation, you must use all synthetic brushes. First of all, because these products are greasy, so it’s much healthier to use a synthetic, and also because synthetic brushes are flat. See, this is a natural hair brush.” He lifted one and wiggled it against the backs of our hands. “It’s fluffy.” It was. “Now, this is synthetic hair.” (It wasn’t.)

“With synthetic, it’s hard to do a good, fluffy brush. With cream anything, you need a synthetic.” The one he favors for cream eyeshadow? Estée Lauder's concealer brush 5. So, there you are—straight from the horse's mouth.