Using aluminum foil when cooking food is a commonality. The main reason behind this preference is that aluminum is a good conductor of heat and therefore, can act as an asset in the cooking process. Although you can use aluminum foil in a toaster, you need to be very careful if you choose to do this. If the aluminum foil, by any chance, touches the heating element of the toaster, it can either damage the toaster itself or in a worst-case scenario, start a fire. Aluminum foil can be a danger to use in a toaster if it starts to melt.