Heat patina refers to the beautiful color change on a surface caused by the application of heat. It occurs when heat interacts with certain materials, such as metal or wood, and creates a unique and visually appealing effect. The colors produced can range from vibrant blues and purples to earthy browns and bronzes, depending on the material and temperature. Heat patina is often admired for its artistic and decorative qualities, making it a popular technique in various crafts and designs.