It is electrically conductive and thermally insulating. Only electrically conductive materials can be machined. The process is useful for applying materials to any electrically conductive surface. Its use is limited to electrically conductive materials. It must be porous, electrically conductive, and thin. Cathode materials must be, at a minimum, electrically conductive. Thermal runaway is more typical of electrically conductive liquids such as salty water. Faraday's law is used for measuring the flow of electrically conductive liquids and slurries. There are also electrodes made out of conductive silicone. Depending on the frequency, they can be constructed from either conductive or dielectric materials. OLEDs consist of an emissive and conductive layer. This construction works with floating electrodes without any conductive connection to the termination. The first is a direct electrical connection known as conductive coupling. Nonmetallic conductors, such as conductive plastic, are sometimes used. Typical materials are salts and conductive polymers.