If your flour sifter is dishwasher-safe, you can toss it in your dishwasher with your dishes and glasses to clean it easily. For sifters that require handwashing, fill the sink with some warm water and dish soap and let the sifter soak for approximately five to ten minutes. If you have an aluminum sifter, though, don’t soak it too long or it may start to rust. Use a toothpick or small bottle brush to scrape away flour if there is any stuck in the mesh screen after cleaning. Rinse the sifter thoroughly and dry it completely before storing it.