If you accidentally leave a product that contains liquid in a microwave for an extended period of time, you may soon find rust inside your microwave. Always remove the rust spot quickly before it grows in size. Fortunately, rust spots can be removed in just a few moments with minimal effort. Unplug your microwave and remove the glass turn table. Flip the microwave over so the area that has rust is facing up. Dampen a rag or cloth and rub it across the rust. Slightly dampen the rust area so your cleaning powder will stick better. Sprinkle Barkeeper's Friend onto the rust. This powder resembles Ajax and is commonly used to clean pots and pans. Allow the powder to sit on the damp rust spots for a few moments. Take another wet cloth and rub the rust area. If any rust remains, repeat the process.