White socks are a wardrobe staple, and I pride myself on having an extensive collection. I have frilly ones to peek out of loafers, soft-and-cushy mainstays for walks and everyday outings, and compression socks for long-haul flights.But unfortunately, white socks tend to develop what could generously be called a “patina” on the soles. And even if you wash them with a high-quality detergent, the dark grime doesn’t always budge during a regular wash cycle.This doesn’t mean it’s time to toss your discolored pairs, though. They simply need a little spa day. I tested nine different methods on the grubbiest cotton socks I could find. I discovered that the best method for removing stubborn stains is also the easiest: an overnight soak in a solution of water, laundry detergent, and oxygen bleach. (Bonus, this solution is safe to use on colorful socks, too.)Here’s how to freshen up your socks before your next shoes-off party.